Shock / Ischemia / CPR / Trauma Flashcards

Question

Which type of catheter should we chose for fluid resuscitation

Answer 1

Because speed of fluid administration is proportional to the diameter of the catheter lumen and inversely proportional to its length, short, large- bore catheters should be placed in a central or peripheral vein.

Answer 2

The administered fluid rapidly distributes into the extracellular fluid compartment so that only approximately 25% of the delivered volume remains in the intravascular space by 30 minutes after infusion.

Answer 3

o Resuscitate with fluids the patient until a MAP of 60mmHg / SAP 80-90mmHg o In patients that are bleeding, it may even be advantageous to perform hypotensive resuscitation until the hemorrhage is controlled, because aggressive fluid therapy in this setting can worsen bleeding and outcome.

Answer 4

Hyperoncotic o Cats 5 to 10 ml/kg compared with 10 to 20 ml/kg in dogs.

Answer 5

o After administration of hypertonic saline, there is a transient (<30 minutes) osmotic shift of water from the extravascular to the intravascular compartment. o It is administered in small volumes (3 to 5 ml/kg) intravenously over 10 minutes. o In addition to the fluid shift caused by hypertonic saline, there is evidence that it also reduces endothelial swelling, modulates inflammation, increases cardiac contractility, causes mild peripheral vasodilation, and decreases intracranial pressure. o The effects of this solution are immediate, with a decrease in heart rate and improvement of pulse quality typically noted within 1 to 2 minutes of administration. o Should always be used in combination with other resuscitative fluids because of the osmotic diuresis and rapid sodium redistribution that occur after administration.

Answer 6

o After administration of hypertonic saline, there is a transient (<30 minutes) osmotic shift of water from the extravascular to the intravascular compartment. o It is administered in small volumes (3 to 5 ml/kg) intravenously over 10 minutes. o In addition to the fluid shift caused by hypertonic saline, there is evidence that it also reduces endothelial swelling, modulates inflammation, increases cardiac contractility, causes mild peripheral vasodilation, and decreases intracranial pressure. o The effects of this solution are immediate, with a decrease in heart rate and improvement of pulse quality typically noted within 1 to 2 minutes of administration. o Should always be used in combination with other resuscitative fluids because of the osmotic diuresis and rapid sodium redistribution that occur after administration.

Answer 7

10 to 20 ml/kg 20 to 30 ml/kg

Answer 8

TRUE Despite these theoretical benefits and the long shelf life of this product, HBOC solutions are not widely used because of inconsistent supply, undesirable side effects, expense, and lack of clear benefit over other solutions available.

Answer 9

Systolic or diastolic cardiac

Answer 10

Furosemide (1 to 8 mg/kg)

Answer 11

It is the force exerted by blood against any unit area of the vessel wall.

Answer 12

Directly Inversely

Answer 13

Systemic Local

Answer 14

o Catecholamines released by the SNS are primarily responsible for basal systemic vascular tone, as well as minute-to- minute regulation of blood pressure. o Angiotensin II and vasopressin, also having vasoconstrictive effects, play more of a role in long-term regulation of vascular tone.

Answer 15

o Local factors can also serve to affect blood flow in response to changes in metabolic demand, muscle activity, and vascular injury and to circumvent systemic vascular control. o Vasodilatory substances such as NO, histamine, prostacyclin, and CO2, as well as vasoconstrictive agents such as endothelin, thromboxane, and thrombin. o Although their effects are to meant to alter local vascular tone, excessive/systemic release can result in significant changes to SVR.

Answer 16

o Reduction in preload. o Reduction in cardiac function. o Reduction in afterload.

Answer 17

o As a reflection of venous return, preload will be affected by any cause of significant fluid loss from the vascular space, including hemorrhage, GI or urinary losses leading to severe dehydration, edema, or cavitary effusions. o Another important cause of relative hypovolemia and preload reduction is venodilation. Veins have a significant capacity for volume; relaxation results in pooling and diminished venous return. o Any major obstruction in venous return will result in a preload reduction and the potential for hypotension to develop (obstructive shock).

Answer 18

o Gastric dilation/volvulus -> gastric distention results in compression of the vena cava and impedes return of blood from caudal circulation. o Twisting of the stomach itself results in venous congestion and trapping of vascular volume away from effective circulation. o Caval or portal venous thrombosis, severe pneumothorax, mesenteric volvulus, massive pulmonary thromboembolism and pericardial tamponade.

Answer 19

o Can occur as a primary disease with dilated cardiomyopathy, characterized by impaired myofibril contraction, decreased contractility, and progressive ventricular dilation. o Secondary myocardial dysfunction can arise associated with severe acidosis or alkalosis, toxin exposure, drug administration, or systemic inflammatory response syndrome (SIRS)/sepsis.

Answer 20

o Myocardial ischemia, microcirculatory dysregulation, impact of various cytokines (TNF alpha, IL1,6), impaired calcium transport, catecholamine insensitivity, and mitochondrial dysfunction function, among others. o No single mechanism has been identified; it is likely a combination of these factors.

Answer 21

o Severe mitral regurgitation is another potential cause of cardiogenic hypotension. As the majority of the left ventricular volume moves backward into the atrium, rather than forward into arterial circulation, there is a significant reduction in effective stroke volume and thereby cardiac output. o Severe tachyarrhythmias (ventricular or supraventricular) and bradyarrhythmias (third- degree AV block, sick sinus syndrome, hyperkalemia) are also potential causes of decreased cardiac output and hypotension.

Answer 22

o Distributive o In susceptible patients, IgE produced in response to allergen exposure binds to mast cells and basophils. This binding triggers release of histamines, leukotrines, and other substances that promote vasodilation and increased vascular permeability.

Answer 23

The baroreceptor reflex system. Through a decrease in stretch of the baroreceptors, it will (not) stimulate the vasomotor center in the medulla and the SNS will lack of inhibition, causing increased HR and SVR.

Answer 24

o Although most emphasis is placed on arterial vasoconstriction, a significant increase venous tone also occurs. o This will cause decreased capacitance and promote venous return, thereby supporting preload.

Answer 25

o The chemoreceptor reflex. o Originating in chemoreceptor organs (such as the carotid and aortic bodies), responds to a decrease in tissue oxygen tension, increase in carbon dioxide, or decrease in pH. o These changes reflect a decrease in blood flow or oxygen delivery rather than a change in blood pressure per se. o Unlike the baroreceptors, these changes cause increased signaling from the chemoreceptors and serve to excite the vasomotor center and promote sympathetic outflow.

Answer 26

o Yes o Acute decreases in blood volume or pressure will also promote the movement of fluid from the interstitium into the vascular space. o Associated decreases in capillary hydrostatic pressure cause a shift in the net balance of Starling’s forces toward the vascular compartment. The resulting internal fluid resuscitation helps to maintain blood volume, preload, and MAP.

Answer 27

FALSE - By both direct (triggering vascular smooth muscle contraction) and indirect actions (stimulation of sympathetic activity and release of vasopressin).

Answer 28

o When in the face of significant hypovolemia/ hypotension (and with further input from the SNS and RAA system), release of vasopressin increases significantly, independent of osmolarity.

Answer 29

o Largely related to the systemic reflection of compensatory mechanisms and, for the most part, occur regardless of the underlying cause. o Tachycardia (sympathetic stimulation of HR), as well as pale mucous membranes, prolonged capillary refill time (CRT), weak peripheral pulses, cool distal extremities, and altered mentation (all reflecting peripheral vasoconstriction or impaired perfusion). o Cats may also demonstrate bradycardia in shock states (especially cardiogenic and vasodilatory). o Patients that are in the early (hyperdynamic) stages of vasodilatory shock may have bounding pulses, red mucous membranes, and shortened CRT to reflect the reduction in SVR and increase in peripheral perfusion. o Many of these signs will develop before a decrease in blood pressure (i.e., during compensation) but should definitely be present once the patient is hypotensive.

Answer 30

o When MAP is below 80mmHg o Concern for impaired tissue perfusion, especially renal, generally does not occur until MAP gets below 60 to 65mmHg. o When MAP is not available (doppler), a systolic blood pressure of less than 90 to 100 mmHg could also be considered to reflect hypotension.

Answer 31

o Direct blood pressure measurement with an arterial catheter and a pressure transducer.

Answer 32

o More accurate than indirect methods, direct measurement provides continuous reporting of systolic, diastolic, and mean pressures, as well as display of the arterial waveform. o Used to detect and treat hypotension on a minute-to- minute basis. o The catheter can be used for arterial blood sampling to monitor acid-base status and blood gas parameters in critically ill patients. o Direct blood pressure monitoring is less commonly used in cats, except for temporary monitoring (anesthesia) because secondary thrombosis and failure to establish collateral circulation are common in this species.

Answer 33

Doppler Oscillometry

Answer 34

FALSE - Tendency to overestimate BP in hypotension and underestimate in hypertension.

Answer 35

40% of the circumference of the limb If the cuff is too large or too small, measurements may underestimate or overestimate the actual blood pressure, respectively.

Answer 36

o Carry the advantage of being more automated and providing information about systolic pressure, diastolic pressure, and MAP. o Unlike Doppler ultrasonography, oscillometric readings do not require patient manipulation after cuff placement, and many devices are easily set to cycle for repeated pressure readings. o Oscillometric measurements are affected by cuff size in a fashion similar to the Doppler technique. o Other limitations that can affect accuracy include small patient size (especially cats), significant motion, low- perfusion states, and arrhythmias.

Answer 37

FALSE - therapy should be initiated at the earliest indication of cardiovascular instability, even if hypotension has not yet developed.

Answer 38

In cases of documented (through echocardiography) or highly suspected (based on clinical picture) myocardial/systolic dysfunction.

Answer 39

o Hypertensive emergency is a patient with an elevated ABP with new or progressive TOD o Hypertensive urgency is a critically elevated ABP with no evidence of TOD.

Answer 40

Patients with a hypertensive emergency require immediate lowering of blood pressure, whereas patients with a hypertensive urgency can have their ABP lowered over hours to days.

Answer 41

FALSE - prevent acute changes in BP

Answer 42

o RAAAS, stress relaxation responses of the vasculature, and fluid shifts between the vascular space and the interstitium respond within minutes to hours to correct abnormalities in blood pressure.

Answer 43

High blood pressure, resulting due to inappropriately high systemic vascular resistance with or without concurrent increases in blood volume.

Answer 44

MAP = CO x SVR Therefore, either increases in blood volume or increases in systemic vascular resistance o CO => Increases in blood volume almost always are due to inadequate volume excretion by the kidneys. This may be due to intrinsic kidney disease or it can occur as a result of active renal reabsorption of salt and water, usually in response to a perceived lack of adequate effec- tive circulating volume or hormonal influence (e.g., aldosterone or glucocorticoid excess). o SVR => Uncontrolled vasoconstriction is due to local and systemic mediators, including catecholamines, angiotensin II, endothelin I, vasopressin, and thromboxane, in addition to inadequate local production of vasodilators such as nitric oxide and prostacyclin.

Answer 45

o Inflammation has been implicated both in the development of hypertension and as a consequence of hypertension. o Oxidative stress has been demonstrated in animal models of hypertension and human clinical patients. o Oxidative stress is associated with endothelial dysfunction and has been suggested to cause hypertension through decreased nitric oxide bioavailability (exact role of ROS in hypertension not known). o The vascular remodeling and endothelial injury that occur as a consequence of hypertension are associated with a proinflammatory response that includes cytokine production, white blood cell activation, and upregulation of endothelial adhesion molecules. o In human patients with hypertensive emergencies, these inflammatory changes can lead to increased endothelial permeability and activation of coagulation cascades and may also contribute to the TOD seen in patients with chronic hypertension.

Answer 46

o Situational hypertension - increases in BP that occur as a consequence of the in-clinic measure- ment process in an otherwise normotensive animal are termed situational hypertension. o Secondary hypertension - persistent, pathologically increased BP concurrent with a disease or condition known to cause hypertension, or hypertension associated with the administration of a therapeutic agent or ingestion of a toxic substance known to cause an increase in BP. o Idiopathic hypertension (aka primary or essential) - persistent pathological hypertension in the absence of any identifiable underlying cause and represents a complex multifactorial disorder involving genetic, lifestyle, and environmental factors. Suspected when reliable BP measurements demonstrate a sustained increase in BP concurrent with normal CBC, serum biochemistry, and urinalysis results. Increased BP may induce polyuria (pressure diuresis), and thus the presence of low urine-specific gravity (<1.030) in a patient with high BP does not establish that kidney disease is present.

Answer 47

o Dogs: CKD, AKI, Cushing's, DM, obesity, primary hyperaldosteronism, pheochromocytoma, hypothyroidism, brachycephalic. o Cats: CKD, Cushing's, DM, obesity, primary hyperaldosteronism, pheochromocytoma, hyperthyroidism

Answer 48

Glucocorticoids Mineralocorticoids EPO-stimulating agents Phenylpropanolamine (PPA) Phenylephrine Ephedrine / pseudoephedrine Chronic high dose NaCl

Answer 49

Cocaine Amphetamine / metamphetamine 5-hydroxytryptophan

Answer 50

o Eyes o Brain o Kidneys o Heart & vessels

Answer 51

o Reported prevalence rates of ocular lesions with hypertension are as high as 100%. o Most often termed hypertensive retinopathy. o Sudden onset of blindness, intra- ocular hemorrhage, and retinal detachment are the most common indications for emergency lowering of ABP. o Other ocular lesions associated include retinal vessel tortuosity, edema, and retinal degeneration. o Effective antihypertensive treatment can lead to retinal reattachment, although restoration of vision is not common and subsequent retinal degeneration leading to blindness may occur.

Answer 52

168mmHg 180mmHg

Answer 53

o Altered mentation, disorientation, lethargy, seizures, balance disturbances, head tilt, nystagmus, behavioral abnormalities, and focal neurologic defects. o Hypertensive encephalopathy is more likely to occur with a sudden rise in ABP or a systolic ABP that exceeds 180mmHg. o This syndrome, in its early phases, is rapidly responsive to lowering of ABP. o Hemorrhagic and ischemic strokes are observed in dogs and cats, and these conditions may generally be distinguished from hypertensive encephalopathy by virtue of their slow and incomplete response to lowering ABP. o Before treating hypertension in the patient with evidence of intracranial disease, Cushing’s reflex (causing hypertension and bradycardia) in response to increased intracranial pressure must be distinguished from neurologic injury secondary to hypertension.

Answer 54

o Hypertensive injury generally manifests as an enhanced rate of decline of renal function, early renal death, and proteinuria. o Proteinuria is a marker of hypertensive nephropathy in humans, and severity was directly related to degree of elevation of ABP in an experimental study of chronic kidney disease in cats. o Treatment of hypertension in cats has been associated with a significant decrease in urine protein/creatinine ratio. o Malignant hypertension is a syndrome of severe, progressive elevations of ABP causing end-organ damage that is often associated with kidney disease and is a recognized cause of rapidly progressive renal injury in rats and people, necessitating quick reductions in ABP. o Hypertensive damage to the canine and feline kidneys is almost always a slow and insidious process, requiring weeks to years to fully manifest, and is rarely a rationale for emergency therapy in dogs and cats.

Answer 55

o Cardiac changes in hypertensive animals may include systolic murmurs, cardiac gallops, and left ventricular hypertrophy. o Although cats with previously undiagnosed hypertension may unexpectedly develop signs of congestive heart failure after receiving fluid therapy, heart failure and other serious complications are infrequent and slow to develop. o While vascular injury within the eye or central nervous system is a rationale for emergent therapy, cardiac changes rarely mandate rapid reductions in ABP.

Answer 56

FALSE - secondary is more common

Answer 57

Hypertensive urgency.

Answer 58

o The current human recommendation is to reduce mean arterial blood pressure by no more than 25% within 1 hour o Then to further reduce the blood pressure to 160/100 to 110 mmHg within the next 2 to 6 hours. o The goal of antihypertensive therapy is to reduce systolic ABP to 110 to 150mmHg. o Excessive drops in blood pressure can precipitate organ ischemia and should be avoided. o Severely hypertensive animals (SBP > 250mmHg), and those with secondary vascular changes, can exhibit signs of hypotension (syncope, weakness, exercise intolerance, and prerenal azotemia) when ABP is lowered rapidly. o This is uncommon if the systolic ABP is maintained above 120 mm Hg.

Answer 59

o Measurement of ABP and assessment for changes related to TOD should be performed at least every 8 to 12 hours initially. o Patients receiving parenteral antihypertensive agents should be assessed more frequently, generally at 1-3h intervals. o Choice of agents, drug dosage, and dosage interval should be adjusted according to ABP, with a goal of maintaining a stable systolic ABP between 110 and 150mmHg without evidence of effects of low ABP. o It is important to carefully reevaluate any patient treated with emergency antihypertensive therapy before instituting further therapy. o Follow-up evaluations should include measurement of ABP, funduscopic examination, and other assessments specific to the individual’s TOD and concurrent diseases. Once TOD and ABP are stabilized, generally within 3 to 5 days, the transition to an oral antihypertensive regimen should be made gradually.

Answer 60

o Normotensive (minimal TOD risk) SBP <140 mm Hg o Prehypertensive (low TOD risk) SBP 140-159 mm Hg o Hypertensive (moderate TOD risk) SBP 160-179 mm Hg o Severely hypertensive (high TOD risk) SBP ≥180 mm Hg

Answer 61

Survival to discharge only 6% to 7%

Answer 62

Every 6 months

Answer 63

o Early recognition o Training - refresher q6m o Crash cart w/ algorithms and dosing charts o Post event-debriefing

Answer 64

o A standardized assessment leading to early recognition of CPA is crucial and should be applied immediately to any acutely unresponsive patient. o In non-anesthetized patients, a diagnosis of CPA should be highly suspected in any unconscious patient that is not breathing. o A brief assessment lasting no more than 10 to 15 seconds based on evaluation of airway, breathing, and circulation (ABCs) will efficiently identify CPA. o If CPA cannot be definitively ruled out, CPR should be initiated immediately rather than pursuing further diagnostic assessment. o The rationale for this aggressive approach includes the following: (a) Pulse palpation is an insensitive test for CPA in people, and this may also be the case in dogs and cats; (b) even short delays in starting CPR in pulseless patients reduce survival rates; and (c) starting CPR on a patient not in CPA carries minimal risks. o Therefore, there should be no delay in starting CPR in any patient with a suspicion of CPA.

Answer 65

o Chest compressions to restore blood flow to the tissues o Ventilation to provide oxygenation of the arterial blood and removal of CO2 from venous blood.

Answer 66

Circulation Airway Breathing

Answer 67

High-quality BLS focused first on chest compressions followed by ventilation.

Answer 68

Respiratory Cardiac

Answer 69

o eRstoration of pulmonary CO2 elimination and oxygen uptake by providing pulmonary blood flow o Delivery of oxygen to tissues to restore organ function and metabolism by providing systemic arterial blood flow.

Answer 70

o During ventricular systole in the spontaneously beating heart, coronary blood flow is negligible and at times may be retrograde; o Several mechanisms have been proposed to explain this finding, including backward pressure waves, the intramyocardial pump theory, coronary systolic flow impediment, and cardiac compression.

Answer 71

o Retrograde coronary blood flow has been described during CPR using external chest compressions. o That the majority of myocardial perfusion during CPR occurs during the decompression phase of chest compressions and is determined predominantly by myocardial perfusion pressure.

Answer 72

o Also known as coronary perfusion pressure (CPP) o CPP = ADP - RADP DAP = aortic diastolic pressure RADP = right atrial diastolic pressure o There is strong evidence that higher MPP during CPR is associated with better success in both humans and dogs, leading to the use of MPP as a primary marker of CPR quality.

Answer 73

o 1/3 to 1/2 the width of the chest o Rate of 100 to 120 compressions per minute regardless of animal size or species.

Answer 74

Higher compression rates lead to higher MPP and coronary blood flow velocity, but because anterograde flow occurred only during chest decompression, net myocardial blood flow decreases at compression rates above 120 per minute, so faster rates should be avoided.

Answer 75

Because it will reduce filling of the heart by preventing full elastic recoil of the chest and must be avoided.

Answer 76

Because it will reduce filling of the heart by preventing full elastic recoil of the chest and must be avoided.

Answer 77

60 seconds

Answer 78

2- 5 seconds To minimize compressor fatigue, a new team member should take over chest compressions during this planned pause.

Answer 79

o Cardiac pump o Thoracic pump

Answer 80

o Direct compression of the left and right ventricles increases ventricular pressure, opening the pulmonic and aortic valves and allowing blood flow to the lungs and the tissues, respectively. o Thoracic elastic properties allow the chest to recoil between compressions, creating a subatmospheric intrathoracic pressure that draws venous blood into the ventricles before the subsequent compression. o Hands placed between 3rd - 5th intercostal space, where we suspect the heart is.

Answer 81

o An increase in overall intrathoracic pressure during a chest compression forcing blood from the thorax into the systemic circulation is proposed in the thoracic pump theory. o Rather than as a pump, the heart acts simply as a conduit for blood flow. o Hands placed in the widest part of the thorax.

Answer 82

Chest size and conformation

Answer 83

o Place them in dorsal recumbency o Cardiac pump with hands over sternum

Answer 84

o The compressor should lock the elbows with one hand on top of the other and position the shoulders directly above the hands. o Engaging the core muscles rather than the biceps and triceps by using this posture will allow the compressor to maintain optimal compression force and reduce fatigue. o The use of a stepstool is recommended if the patient is on a table and the elbows cannot be locked. o Alternatively, the compressor can kneel over the patient by climbing onto the table or placing the patient on the floor.

Answer 85

FALSE - cats and small dogs have chests that are more compliant than medium to large dogs.

Answer 86

o A single-handed technique with the hand wrapped around the sternum and compressions achieved by squeezing the chest. o Circumferential compressions of the chest using both hands may also be considered.

Answer 87

FALSE - ventilate after chest compressions have started

Answer 88

FALSE - simultaneously

Answer 89

The inflated endotracheal tube cuff prevents gastric insufflation with air, allows pulmonary inflation during chest compressions, and minimizes interruptions in chest compressions.

Answer 90

Ventilation rate of 10 breaths/min, a short inspiratory time of approximately 1 second, and a tidal volume of approximately 10 ml/kg.

Answer 91

o Because pulmonary blood flow is reduced. o Because low arterial CO2 tension causes cerebral vasoconstriction, leading to decreased cerebral blood flow and oxygen delivery, hyperventilation must be avoided. o In addition, increased intrathoracic pressure caused by positive pressure ventilation will impede venous return to the chest, reducing effectiveness of chest compressions and reducing MPP. o Therefore limiting the ventilation rate to reduce the mean intrathoracic pressure will improve cardiac output.

Answer 92

o Mouth-to-snout ventilation is an alternative breathing strategy and will provide sufficient oxygenation and CO2 removal but should only be used if endotracheal intubation is not possible. o Firmly close the animal’s mouth with one hand while extending the neck to align the snout with the spine. o The rescuer should then make a seal over the patient’s nares with his or her mouth and inflate the lungs by blowing firmly into the nares while visually inspecting the chest during the procedure, continuing the breath until a normal chest excursion is accomplished. o An inspiratory time of approximately 1 second should be targeted.

Answer 93

o No o Ventilation cannot be accomplished simultaneously with chest compressions in nonintubated patients. o Rounds of 30 chest compressions should be delivered, immediately followed by two short breaths. o Compressions and mouth-to-snout breaths at a ratio of 30:2 should be continued for 2 minute cycles and the rescuers rotated every cycle to prevent fatigue. o This technique necessitates pauses in chest compressions and should only be employed when endotracheal intubation is impossible because of lack of equipment or trained personnel.

Answer 94

ECG and ETCO2

Answer 95

o ECG is highly susceptible to motion artifact and cannot be interpreted during ongoing chest compressions. o To minimize pauses in chest compressions, the only time the ECG should be evaluated is between 2-minute cycles of BLS while compressors are being rotated

Answer 96

o The team leader should clearly announce the rhythm diagnosis and invite other team members to express agreement or dissent to minimize misdiagnosis. o In the event of differing opinions on the rhythm diagnosis, chest compressions should be resumed immediately and discussion should proceed into the next cycle.

Answer 97

The three most common arrest rhythms leading to CPA in dogs and cats are asystole, pulseless electrical activity (PEA), and ventricular fibrillation (VF)

Answer 98

o To assess endotracheal tube placement o To monitor quality of chest compressions

Answer 99

poor pulmonary blood flow

Answer 100

o Because when minute ventilation is held constant, ETCO2 is proportional to pulmonary blood flow. o A very low ETCO2 value during CPR (<10 to 15 mm Hg) has been associated with a reduced likelihood of ROSC in dogs and humans. o ETCO2 substantially increases upon ROSC and therefore is a valuable early indicator of ROSC during CPR.

Answer 101

When high quality BSL is established

Answer 102

o Monitoring o Drugs o Defibrillation

Answer 103

Because cardiac output during CPR is generally 30% of normal or less, increasing peripheral vascular resistance to redirect blood flow from the periphery to the core can be useful regardless of the arrest rhythm.

Answer 104

o Epinephrine is a catecholamine that causes peripheral vasoconstriction via stimulation of α1 receptors but also acts on β1 and β2 receptors. o The α1 effects have been shown to be the most beneficial during CPR, and these vasoconstrictive effects predominate in the periphery while sparing the myocardial and cerebral vasculature and preserving blood flow to these core organs. o A meta-analysis showed that low-dose epinephrine (0.01 mg/kg intravenously [IV]/ intraosseously [IO] every other cycle of CPR) was associated with higher rates of survival to discharge in people, compared with high-dose epinephrine (0.1 mg/ kg IV/IO every other cycle of CPR). o Therefore early in CPR low- dose epinephrine is recommended. o However, after prolonged CPR, a higher dose (0.1 mg/kg IV/IO every other cycle of CPR) may be considered because of evidence that this dose is associated with a higher rate of ROSC.

Answer 105

Endotracheal administration of epinephrine is possible (0.02 mg/kg low dose; 0.2 mg/kg high dose) and should be accomplished by feeding a long catheter through the tube and diluting the epinephrine 1 : 1 with isotonic saline or sterile water.

Answer 106

o An alternative to epinephrine is vasopressin (0.8 U/kg IV/IO every other cycle of CPR), a vasopressor that will activate peripheral V1 receptors. o It may be used interchangeably or in combination with epinephrine during CPR. o Unlike epinephrine, it is efficacious in acidic environments in which α1 receptors may become unresponsive to epinephrine. o It also lacks the inotropic and chronotropic β1 effects that may worsen myocardial ischemia in patients that achieve ROSC. o Like epinephrine, vasopressin may be administered endotracheally as described earlier.

Answer 107

o Its administration may be considered during CPR in all dogs and cats (0.04 mg/kg IV/IO every other cycle of CPR) and may be especially useful in patients with asystole or PEA associated with increased vagal tone, such as occurs with chronic and severe or acute gastrointestinal, respiratory, or ocular disease. o Endotracheal administration is also possible (0.08 mg/kg).

Answer 108

o Patients with VF refractory to electrical defibrillation may benefit from treatment with the antiarrhythmic drug amiodarone at a dose of 2.5 to 5 mg/kg IV/IO. o There are reports of anaphylactic reactions in dogs, so close monitoring for signs of anaphylaxis is warranted once ROSC is achieved; if noted, they should be treated appropriately. o Lidocaine (2 mg/kg slow IV/IO push) is a less effective alternative to amiodarone for patients with refractory VF. o Although lidocaine has been shown to increase the energy required for successful electrical defibrillation in dogs in one study, others have shown that this drug is beneficial.

Answer 109

o Reversal agents! o Naloxone (0.04 mg/kg IV/IO) for opioids, flumazenil (0.01 mg/kg IV/IO) for benzodiazepines, and atipamezole (0.05 mg/kg IV/IO) or yohimbine (0.11 mg/kg IV/IO) for α2 agonists.

Answer 110

o Reversal agents! o Naloxone (0.04 mg/kg IV/IO) for opioids, flumazenil (0.01 mg/kg IV/IO) for benzodiazepines, and atipamezole (0.05 mg/kg IV/IO) or yohimbine (0.11 mg/kg IV/IO) for α2 agonists.

Answer 111

o No o Administration of intravenous fluid boluses during CPR may be harmful to euvolemic or hypervolemic patients because they tend to increase central venous (and hence right atrial) pressure rather than arterial blood pressure in patients in CPA. o This elevation in right atrial pressure can compromise perfusion of the brain and heart by decreasing MPP and cerebral perfusion pressure. o Conversely, patients with documented or suspected hypovolemia will likely benefit from intravenous fluids, which will help to restore adequate preload and may increase the efficacy of chest compressions and improve arterial systolic and diastolic pressures, leading to increased cerebral perfusion pressure and MPP.

Answer 112

o Most studies have shown no definitive evidence of benefit or harm from corticosteroid administration during CPR, although most were confounded by coadministration of other drugs. o One prospective observational study in dogs and cats showed an increased rate of ROSC in dogs and cats, but the type and dose of steroids administered were highly variable and a causative effect could not be inferred because of the study design. o It is well known that significant gastrointestinal ulceration can develop from a single high dose of corticosteroids. o In addition, immunosuppression and reduced renal perfusion because of decreased renal prostaglandin production are known side effects. o Because of this nonadvantageous risk/benefit ratio, the routine use of corticosteroids is NOT recommended during CPR.

Answer 113

o Severe metabolic acidosis can develop with prolonged CPA (>10 to 15 minutes), leading to inhibition of normal enzymatic and metabolic activity as well as severe vasodilation. o Administration of sodium bicarbonate (1 mEq/kg, once, diluted IV) may be considered in these patients. o It should be remembered that these metabolic disturbances may resolve rapidly after ROSC; therefore bicarbonate therapy in patients with prolonged CPA should be reserved for those with severe acidemia (pH < 7) of metabolic origin.

Answer 114

o Electrical defibrillation

Answer 115

o The initial electrical phase during the first 4 minutes is characterized by minimal ischemia and continued availability of cellular energy stores to maintain metabolic processes. o The subsequent 6 minutes, constituting the circulatory phase, are characterized by reversible ischemic injury caused by depletion of cellular adenosine triphosphate (ATP) stores. o After 10 minutes, the metabolic phase and potentially irreversible ischemic damage begin.

Answer 116

Chest compressions should be continued only until the defibrillator is charged, and the patient should then be defibrillated immediately.

Answer 117

o One full cycle of CPR should be done before defibrillating. o This allows blood flow and oxygen delivery to the myocardial cells, which can then generate ATP and restore normal membrane potentials, making the cells more likely to respond favorably to electrical defibrillation.

Answer 118

o Monophasic defibrillators deliver current in one direction between the paddles and across the patient’s chest. o Biphasic defibrillators deliver current in one direction before reversing polarity and delivering a current in the opposing direction. o Biphasic defibrillators have been shown to successfully defibrillate patients at a lower energy output, leading to less myocardial damage, and are therefore recommended over monophasic devices.

Answer 119

o Monophasic defibrillators 4 to 6 J/kg o Biphasic defibrillation dosing starts at 2 to 4 J/kg. o The dose may be increased by 50% with each defibrillation attempt up to a maximum dose of 10 J/kg.

Answer 120

o ALS algorithms no longer recommend three stacked shocks. o Instead, chest compressions should be resumed immediately after a single defibrillation attempt without a pause for rhythm analysis. o A full 2-minute cycle of BLS should then be administered before reassessing the ECG. o If the patient is still in VF, defibrillation should be repeated at the end of this cycle of BLS.

Answer 121

o A number of experimental studies in dogs and clinical studies in people indicate improvements in hemodynamic variables, MPP and cerebral perfusion pressure, and outcome when comparing OCCPR and closed-chest CPR. o There is also evidence that delays in starting OCCPR lead to poorer outcomes and that after 20 minutes of closed-chest CPR in dogs OCCPR is unlikely to be effective. o Current evidence suggests that improved outcomes from CPA are likely with OCCPR compared with closed- chest CPR, and in cases in which owner consent has been obtained and no underlying diseases that would be contraindications to OCCPR are present (such as thrombocytopenia or coagulopathy), the procedure should be employed as soon as possible after diagnosis of CPA.

Answer 122

o A left lateral thoracotomy in the fourth to fifth intercostal space is performed with the animal in right lateral recumbency, and Finochietto retractors are used to open the chest for access to the heart. o The pericardium may be removed in all cases to facilitate compressions but should always be removed in patients with pericardial effusion or other pericardial disease. o The ventricles can then be directly compressed using either a two-hand technique with the right ventricle cupped in the left hand and the fingers of the right hand placed over the left ventricle or a one-hand technique with the fingers of the right hand placed over the left ventricle and the heart compressed against the sternum. o Care should be taken to compress the ventricles from apex to base to maximize forward blood flow. If ROSC is achieved, intensive post–cardiac arrest care will be required after the thoracotomy is closed and a chest tube placed to reduce the risk of pneumothorax.

Answer 123

o Conditions making external chest compressions futile include pleural space disease, pericardial effusion, and penetrating thoracic injuries. o In addition, it is likely that closed-chest CPR will be ineffective in giant-breed dogs with round or barrel-chested conformation and OCCPR is preferable. o Patients already in surgery that experience CPA should likely have OCCPR rather than closed-chest CPR. In patients undergoing abdominal surgery, the heart is easily accessible via an incision in the diaphragm, so thoracotomy is not required.

Answer 124

47% survival to discharge for dogs 42% survival to discharge for cats

Answer 125

o 45% ROSC, only 17% survival to discharge o 35-45% ROSC, 6-7% survival to discharge

Answer 126

o On guidelines -> circulation no longer recommended, is not very reliable o It is ok to do it as long as the assessment does not take longer than 10-15 sec

Answer 127

Intratracheal -> not clear, from 2 to 10 times more than the IV dose

Answer 128

o Shockable rhythms -> pulseless ventricular tachycardia or ventricular fibrillation o Non-shockable rhythms -> asystole or pulseless electrical activity (PEA) o ROSC

Answer 129

o Half-life of atropine a bit longer, no need to give it every other cycle, but guidelines say we can give it every other cycle

Answer 130

o No, if they are hyperoxemic we can make the ischemia reperfusion injury therefore we should decrease the FiO2 o Same, hypoxemia not ideal, we want normoxemia o If we need >0,6 FiO2, then consider PPV

Answer 131

Does my patient has a good DO2

Answer 132

o No o If they are hypotensive, they are for sure in the supply dependent part of the VO2/DO2 curve, but once they are normotensive we do not know where they stand. o That is because DO2 depends on CO x CaO2, therefore we have optimized the CO part but we need to check where they are in the CaO2 part of the equation

Answer 133

o With central venous oxygen saturation - ScvO2 o In a healthy patient at rest, ScvO2 should be more than 70% - if we are pushing the right amount of O2 from the arteries, there should be still a lot of O2 left in the veins.

Answer 134

o Neuro protection o Hypothermia if comatose - can be protective, especially for the brain but also for all tissues as it reduces inflammatory processes and production of ROS - do not raise temp more than 1 degree / hour -> most likely they will need the vent o Mannitol / hypertonic -> neurons have been ischemic, they have been firing a lot and probably having a lot of Na intracellularly, consider osmotic therapy. o If they have a seizure in the PCA period we should treat them.

Answer 135

FALSE - only in monophasic defibrillators in dogs. In pigs it has been shown that it does not happen with biphasic.

Answer 136

o Ischemia / reperfusion injury o PCA brain injury o PCA myocardial dysfunction o Persistent precipitating pathologic conditions

Answer 137

The goal immediately after ROSC is to sustain spontaneous circulation and perfusion of vital organs, such as the brain and the myocardium, attenuating further injury and preventing rearrest.

Answer 138

o In people, shockable and nonshockable rhythms are equally prevalent, with ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) identified in 15% and 29%, respectively. o The incidence of rearrest rhythms has not been systematically reported in veterinary patients.

Answer 139

20 to 40 minutes

Answer 140

o The syndrome shares many characteristics with sepsis, specifically in regard to inflammation, coagulation, and the endothelium. o Sepsis-like syndrome

Answer 141

1) Early hemodynamic optimization 2) Glycemic control 3) Critical illness–related corticosteroid insufficiency (CIRCI)

Answer 142

o Central venous pressure (CVP; 0 mm Hg < CVP < 10 mm Hg) o Mean arterial blood pressure (MAP 80 to 120 mm Hg) o Perfusion parameters (central venous oxygen saturation [ScvO2] > 70 %; lactate < 2.5 mmol/L). o Markers of vasodilation, such as injected mucous membranes or shortened capillary refill time, pulse quality, and echocardiographic determination of LV function should also be included in a comprehensive hemodynamic assessment.

Answer 143

o Mild to moderate hyperglycemia combined with a total plasma insulin decrease of 60% was observed in experimental research in dogs early after ROSC. o Animal studies (including canine) have demonstrated that hyperglycemia worsens ischemic brain injury. o In humans, iatrogenic hypoglycemia occurred in 18% of PCA patients treated with tight glycemic control (4.4 to 6.1 mmol/L; 80 to 110 mg/dl). o There is no evidence that tight glucose control provides additional benefits over a less stringent target, and moderate glycemic control targeting glucose levels less than 180 mg/dl is currently suggested for human PCA patients. o A similar strategy in dogs and cats after cardiac arrest may be considered. Implementation of glycemic control with intravenous insulin administration follows the recommendation for patients with severe sepsis.

Answer 144

FALSE - it was identified in several human clinical studies and has been associated with increased mortality.

Answer 145

o Low-dose steroid administration for septic shock remains controversial, and direct evidence supporting corticosteroid administration during PCA care is lacking. o Because of this and the risk for infection, peptic ulcer, and exacerbation of postischemic neurologic injury associated with corticosteroid administration, routine administration of corticosteroids during PCA care is not recommended. o However, administrationof low-dose hydrocortisone (1 mg/kg IV followed by either 1 mg/kg IV q6h or an intravenous infusion of 0.15 mg/kg/hr) in dogs and cats with vasopressor dependent shock after CPA, with or without documented CIRCI, may be considered.

Answer 146

Cerebral dysfunction

Answer 147

From global cerebral ischemia

Answer 148

o Much of the injury sustained after CPA evolves during reperfusion rather than ischemia. However, IR is a continuum that is initiated during cellular ischemia. o A sudden decline in oxygen delivery occurs upon onset of CPA. Glycolysis allows for limited continued energy production, but cerebral ATP stores are depleted within 2 to 4 minutes (20 to 40 minutes are required for the same to occur in the intestines and the myocardium). o Once ATP is depleted, cellular membrane potentials are rapidly lost. Any cardiac electrical activity as detected by ECG provides evidence that the global myocardial membrane potential has not yet subsided, or, during reperfusion, has been reestablished once again. o Large amounts of Na, Cl, and Ca enter the cells, followed by cell swelling and membrane disruption. It is believed that the combined influences of increased exposure to Ca, oxidative stress, and energy depletion lead to mitochondrial injury, finally leading to more ROS production upon reperfusion and to apoptosis and necrosis. o Therefore, controlled reperfusion strategies include mild hypoCa and avoidance of hyperoxemia.

Answer 149

Hydroxyl radicals Peroxynitrite

Answer 150

FALSE - hyperoxemia increases oxidative brain injury, increases neurodegeneration, worsens functional neurologic outcome, and negatively affects overall survival.

Answer 151

linear relationship

Answer 152

94% to 96% 1

Answer 153

o Should be titrated to normoxemia -> PaO2 80 to 100 mm Hg; SpO2 94% to 98% o Avoid both hypoxemia and hyperoxemia.

Answer 154

o Reduction of mitochondrial injury and dysfunction o Decrease in cerebral metabolism o Reduction of Ca inflow into cells and neuronal excitotoxicity o Reduced production of ROS and reduced apoptosis o Suppression of seizure activity.

Answer 155

o Reduction of the core body temperature to 32° to 34°C (89.6° to 93.2° F). o A variety of cooling methods have been used in humans, including cooling blankets, simple icepacks, intravenous infusion of ice cold saline, and endovascular cooling devices. o Cooling to target temperature early after ROSC, or even during reperfusion, is likely more effective than a delay in cooling. o The optimal duration of MTH is unknown, and likely varies, with the more severely injured patients requiring a longer duration of cooling. o MTH for 24 to 48 hours is recommended in dogs and cats that remain comatose after ROSC, followed by rewarming at a slow rate of 0.25° to 0.5°C (0.45° to 0.9°F) per hour.

Answer 156

o Cooling induces increased muscle tone and shivering, which in return leads to increased oxygen consumption, metabolic rate, and respiratory and heart rates and requires sedation, endotracheal intubation, and ventilation. o Cooling without sedation may abolish the protective effect of MTH. o Other physiologic disturbances can occur, including changes in metabolism, acid-base status, electrolytes, ECG, drug elimination, coagulation, and immune function, and the clinician should be familiar with those alterations when using PCA cooling.

Answer 157

TRUE - hypothermia can cause severe derangements in coagulation and immune system

Answer 158

o Many small animals are spontaneously hypothermic after CPA. o Allowing the patient to slowly rewarm to normal core temperature over many hours after CPA without quick active rewarming (permissive hypothermia) offers an alternative to MTH. o Even though the entire potential of MTH will not be realized with this approach, it may attenuate the harmful effects of a rapid increase in brain temperature after ischemia. o It is reasonable to target a rewarming rate of 0.25°C to 0.5°C (0.45° to 0.9°F) per hour. o In addition, it is important to prevent fever or hyperthermia after CPA because it is associated with increased mortality.

Answer 159

FALSE - Nonconvulsive SE (i.e., only identified by electroencephalography) occurs commonly in humans who remain comatose after ROSC.

Answer 160

o Seizure activity leads to a drastic increase in cerebral metabolism and oxygen demand, possibly out- stripping oxygen supply. o Patients should be monitored for seizures and treated accordingly if they occur. o Prophylactic administration of barbiturates should also be considered. o This may be particularly relevant in animals that remain comatose or are sedated, because nonconvulsive seizure activity may be present and difficult to diagnose.

Answer 161

o Cytotoxic and vasogenic cerebral edema have been described after CPA and are associated with poor neurologic outcome in people. o In contrast, intracranial hypertension does not commonly occur, but if it does it can compromise CPP and thus cerebral blood flow.

Answer 162

o In dogs, hypertonic fluid administration after 14 minutes of anoxic brain injury decreased cerebral edema but did not affect survival or functional neurologic outcome. o The use of hypertonic solutions such as mannitol or hypertonic saline for reduction of cerebral edema after cardiac arrest has not been well examined, and the few studies available demonstrate neither benefit nor harm. o Thus the use of mannitol or hypertonic saline can be considered if the presence of cerebral edema is suggested by clinical signs, such as coma, stupor, or decerebrate posture. o Unfortunately the clinical signs of ICH overlap with the neurologic deficits often seen after CPA.

Answer 163

TRUE o In addition to an increased ICP, perivascular edema, intravascular coagulation, and a loss of blood flow autoregulation may also be responsible for the beneficial effect of supranormal cerebral perfusion pressures after prolonged cardiac arrest

Answer 164

FALSE - it is disturbed for the first several hours after prolonged ischemia such that arterial vasodilation in response to increasing PaCO2 is abolished. o With shorter durations of cerebral ischemia or later after reperfusion, CO2 responsiveness was maintained or restored such that hyperventilation after ROSC reduced cerebral blood flow and worsened neurologic outcomes compared with normoventilation.

Answer 165

o Avoid both hypoventilation and hyperventilation after ROSC o Control ventilation such that normoventilation is achieved (dog: PaCO2 32 to 42 mm Hg; cat: PaCO2 26 to 36 mm Hg)

Answer 166

FALSE - every 2-4h

Answer 167

o The Modified Glasgow Coma Scale, originally developed for dogs with traumatic brain injury, can be used to systematically assess and track the patient’s overall PCA neurologic status, although it has not been validated for this. o The MGCS assesses function of the brainstem (cranial nerve reflexes) and cerebral hemispheres (motor response) in conjunction with the level of consciousness. o Any retention of normal neurologic function immediately after ROSC supports a favorable prognosis.

Answer 168

o Studies of comatose human survivors of CPA suggest that clinical neurologic examination is not a reliable predictor of poor outcome during the first 24 hours after ROSC. o Early absence of PLR in comatose patients led to a false-positive rate for prediction of irreversible unconsciousness of more than 30%

Answer 169

24 and 72 hours

Answer 170

o It is not until 3 days after ROSC that lack of PLR and absence of motor response to a painful stimulus predict reliably that a human patient will fail to regain consciousness. o Sedation and MTH will further delay the ability for definitive prognostication.

Answer 171

o EEG o BAER - brainstem auditory evoked response o SSEP - somatosensory evoked potentials

Answer 172

Brain imaging modalities, such as computed tomography or magnetic resonance imaging, are currently insufficiently validated for prediction of neurologic outcomes.

Answer 173

Clinical findings and in some instances BAER or EEG

Answer 174

o Increased CVP and PCWP o Reduced left- and right sided systolic and diastolic ventricular function with increased end-diastolic and end-systolic volume o Reduced LV ejection fraction and CO. o These changes may be further complicated by ventricular tachyarrhythmia, together leading to cardiogenic shock in severe cases.

Answer 175

FALSE - It is reversible and typically resolves within 48 hours

Answer 176

o Stunned myocardium is myocardium affected by transient reversible myocardial contractile dysfunction induced by acute ischemia. o The blood supply to stunned myocardium is almost completely restored upon reperfusion and the myocardium does not suffer metabolic damage.

Answer 177

o Myocyte dysfunction results from cellular processes associated with cellular IR comparable to those evolving in the nervous system. o The severity of MD depends on the duration and extent of myocardial ischemia as well as the conditions under which reperfusion occurs (e.g., presence or absence of hypothermia). o Second, a lack of capillary blood flow during PCA (myocardial no-reflow) may occur. o Microvascular obstruction or plugging may occur subsequent to endothelial cell activation and swelling, neutrophil–endothelial cell interactions, activation of coagulation, and platelet aggregation. o Pericapillary edema will further impede microvascular blood flow. o With alterations in capillary permeability, the subsequent increase in microvascular hematocrit and total protein and the associated rheologic properties, tissue blood flow can be impaired. Postischemic red blood cells may have reduced deformability and have a tendency toward endothelial cell adhesion and to form erythrocyte plugs.

Answer 178

o Intra-arrest administration of epinephrine. o High energy and monophasic waveform defibrillation.

Answer 179

Serial echocardiography

Answer 180

36% 18% 13% 8% 6% 5% 2% 21%

Answer 181

Asystole and PEA Pulseless VT or VF

Answer 182

o Includes monitoring of basic physical examination parameters, ECG and blood pressure. o CVP, ScvO2, and lactate clearance and base deficit o It also includes most advanced forms including pulmonary artery pressure (PAP), mixed venous oxygen saturation (SvO2), and other technologies to measure CO, cardiac index, SVR, DO2 and VO2.

Answer 183

o It is commonly employed to permit fluid therapy to be tailored to the patient’s needs, especially when combined with monitoring of physical examination parameters, urine output, and CVP. o It is essential in guiding the use of inotropic agents and vasopressors; these therapies should not be used unless blood pressure can and will be measured frequently.

Answer 184

o Dogs: SBP, 150 ± 20mmHg; MAP, 105 ± 10mmHg; DBP, 85 ± 10mmHg. o Cats: SBP 125 ± 10mmHg, MAP 105 ± 10mmHg, and DBP 90 ± 10mmHg.

Answer 185

MAP = (2 x DBP) + SBP / 3

Answer 186

Two main categories, noninvasive and invasive methods

Answer 187

Non invasive - doppler and oscillometric

Answer 188

Noninvasive blood pressure monitoring is based on inflation of a cuff to occlude arterial flow, followed by measurement of the pressure at which flow returns.

Answer 189

Approximately 40% of the circumference of the limb for dogs and 30% of the circumference of the limb for cats.

Answer 190

Doppler is useful in patients with hypotension or those that have arrhythmias because the oscillometric methods are commonly inaccurate or do not give any readings at all in these circumstances.

Answer 191

o The Doppler method uses a 10-MHz ultrasound probe to detect blood flow in an artery. o The probe is placed over an artery distal to the cuff. o Doppler sounds become audible when pressure in the cuff is less than the pressure in the artery. o Although the Doppler method typically is regarded as measuring the systolic pressure, one study that compared Doppler readings with direct blood pressure monitoring in anesthetized cats found that the Doppler reading consistently underestimated systolic pressures by 10 to 15 mmHg and was more closely correlated with mean arterial pressure. This study was performed only in anesthetized healthy cats, so limitations are present.

Answer 192

o The cuff is alternately inflated and deflated, and during deflation alterations in cuff pressure due to pulse pressure changes are sensed by the transducer. o The peak amplitude of oscillations equals the mean arterial pressure. o Systolic pressure equals the pressure at which oscillations are first detected, and diastolic pressure equals the pressure at which oscillations decrease rapidly.

Answer 193

o Oscillometric machines calculate systolic and diastolic blood pressure from the mean arterial pressure using built-in algorithms, so that the mean arterial pressure is the most accurate value. o The HR is measured as the number of oscillations occurring per minute and should always be compared with the patient’s heart rate as determined manually or by ECG.

Answer 194

o HDO devices are designed to have advantages over standard oscillometric monitors because HDO performs real-time analysis of arterial wall oscillations to obtain pressure-wave amplitudes, so systolic and diastolic pressures are measured instead of calculated. o Other reported benefits include accurate readings of values from 5 to 300mmHg and high- speed analysis that allows for measurements at heart rates of up to 500 beats/min and during arrhythmias. o However, recent studies have not shown good correlation with other blood pressure monitoring methods, although none compared HDO with direct arterial blood pressure monitoring.

Answer 195

o Originally designed for use on the human finger, photoplethysmogpaphy is based on the “volume clamp” principle. o The blood volume in an extremity varies in a cyclic pattern with each cardiac cycle. The variation is detected by a photoplethysmograph attached to a finger (or to the foot or tail in veterinary patients). o If the cuff is inflated and deflated fast enough to maintain a constant volume in the finger (or distal extremity), the cuff pressure will equal intraarterial pressure. o This allows for a constant, real-time display of cuff pressure, and therefore intraarterial pressure, and measurement of systolic and diastolic pressures. o Photoplethysmography has been evaluated in dogs and cats and found to be accurate, but has not come into common use.

Answer 196

o Direct arterial blood pressure monitoring in patients with hypovolemic or septic shock is extremely helpful in guiding volume replacement and the use of pressors to maintain an acceptable systemic blood pressure. o By evaluating the pressure waveform with various arrhythmias, the clinician can distinguish which ones are causing poor pressures or even pulse deficits, and this can influence the decision to initiate treatment.

Answer 197

o Is not indicated in active, relatively healthy patients because of possible morbidity from arterial catheter placement and the risk of hemorrhage due to disconnection of the arterial line or premature removal by the patient. o Animals with arterial catheters must be strictly supervised at all times.

Answer 198

o Once an arterial catheter is placed, it is connected to semirigid tubing that has been primed with heparinized saline from a bag of 0.9% sodium chloride with 1 unit of heparin per milliliter of saline. o The fluid bag is pressurized to 300 mm Hg to prevent backward flow of arterial blood into the tubing. o The tubing from the catheter is attached to a pressure transducer that is connected to a cable and mounted on a board placed at the level of the patient’s heart. o The pressure transducer converts the pressure changes into an electrical signal that is carried to the monitor by the transducer cable, and then the signal is amplified and displayed on a monitor as a pressure waveform. o Monitors can also display numeric values for the systolic, diastolic, and mean arterial pressures.

Answer 199

If compliant tubing is used, the catheter is lodged up against the arterial wall, a clot forms at the tip of the catheter, air bubbles are present in the catheter or tubing, or the catheter or tubing becomes kinked, amongst others.

Answer 200

o Hematoma formation at the site of arterial puncture, infection, thrombosis of the artery, or necrosis of the tissues distal to the catheter (particularly in cats that have an indwelling catheter for longer than 6 to 12 hours). o Keeping the arterial line patent requires heparinization of the line and catheter, which can be of concern in very small patients. o Fortunately, all of the complications other than hematoma formation are quite rare.

Answer 201

CVP is the hydrostatic pressure in the intrathoracic vena cava and, in the absence of a vascular obstruction, is approximately equal to right atrial pressure.

Answer 202

o Hypovolemic or have septic shock, heart disease, or renal disease (especially oliguric or anuric kidney injury)

Answer 203

o No o A study evaluating the correlation between peripheral venous pressure and CVP in awake dogs and cats found that peripheral venous pressure could not be used to approximate CVP.

Answer 204

o The tip of the catheter should be positioned in the cranial or caudal vena cava just outside of the right atrium. o The catheter is then connected to a three-way stopcock via noncompliant tubing and to a pressure transducer (same for direct arterial blood pressure monitoring). o The central catheter can be used for CVP monitoring as well as fluid administration or intermittent blood sampling. o If the CVP is to be monitored continuously and the patient requires additional venous access, a multilumen venous catheter should be placed so that the other ports remain available for fluid therapy, infusions, and blood sampling. o When the central venous catheter is connected to the system, the zero reference point for the bottom of the pressure transducer should be the manubrium for a patient in lateral recumbency or the point of the shoulder for a patient in sternal recumbency.

Answer 205

o Normal ranges for mean CVP are 0 to 5 cm H2O, but they can vary in individual animals. o This makes trends in the CVP much more significant than individual readings.

Answer 206

o Values can be affected by patient position, so a consistent position should be used when comparing values. o Catheter position also affects readings and can be confirmed by radiography or fluoroscopy.

Answer 207

o Because CVP reflects right atrial pressure. o During inspiration, intrathoracic pressure decreases and the CVP falls. o The reverse occurs during exhalation. If a patient has an upper airway obstruction and has difficulty inspiring, these changes will be exaggerated. o Positive pressure ventilation will reverse this pattern.

Answer 208

o Three positive waves are seen, a, c, and v waves, and two negative depressions are seen, x and y descents. o The a wave represents the increase in the CVP caused by right atrial contraction. o The c wave is caused by bulging of the tricuspid valve into the right atrium, which increases right atrial pressure and CVP as the right ventricle contracts. o The x descent is caused by the decrease in atrial pressure during ventricular ejection. o The v wave is caused by increasing pressure from blood flowing into the right atrium before the tricuspid valve opens. o The y descent represents rapid emptying of the right atrium as the tricuspid valve opens, allowing blood to flow into the right ventricle.

Answer 209

Tricuspid regurgitation

Answer 210

o A low CVP (<0 cm H2O) indicates hypovolemia due to fluid loss or vasodilation secondary to decreased peripheral venous resistance. o A high CVP (>10 cm H2O) may indicate volume overload, right- sided heart failure, or significant pleural effusion. o CVP readings of higher than 16 cm H2O often lead to edema formation or body cavity effusions.

Answer 211

o Right-sided myocardial failure, pericardial effusion and tamponade, restrictive pericarditis, and volume overload from excessive intravenous fluid administration.

Answer 212

o The vascular bed is a very compliant system, able to accommodate changes in volume with minimal changes in pressure. o If the patient has a low CVP due to hypovolemia, the CVP will either show no change or will have a transient rise toward normal, then rapidly decrease again. The mean arterial pressure may also increase with the test bolus, then return toward prebolus measurements. o A small increase of 2 to 4 cm H2O with a return to baseline within 15 minutes is usually seen in euvolemic patients. o A large increase (>4 cm H2O) and slow return to baseline (>30 minutes) is seen in hypervolemic animals or those with reduced cardiac compliance.

Answer 213

o Contraindications for CVP measurement are few and relate to central venous catheter placement. o These include coagulopathies, high risk of thromboembolic disease and suspicion of increased intracranial pressure.

Answer 214

o The biggest limitation of CVP monitoring is that it measures the pressures on the right side of the heart instead of the left side because it is the left side that supplies the systemic circulation and drains the pulmonary circulation. o Pressures in the left side are more accurate in guiding fluid therapy, but their measurement requires use of a pulmonary artery catheter.

Answer 215

o Allows for measurement of the systolic, diastolic, and mean PAP. o If the catheter is equipped with a balloon, PAOP can be measured when the balloon at the end of the catheter is inflated in a distal branch of the pulmonary artery. o Inflation of the balloon eliminates PAP created by blood flow, and the measured pressure reflects the left atrial filling pressure as it equilibrates across the pulmonary capillary bed. o When the mitral valve is open, left atrial pressure equals left ventricular end-diastolic pressure. This pressure provides the best measure of left ventricular preload and is the best predictor of pulmonary edema secondary to fluid overload. o Preload is the amount of stretch in the ventricle at the end of diastole and is an important determinant of cardiac output.

Answer 216

o Like CVP, PAP and PAOP can be used for (and are more accurate at) determining the fluid volume status of a patient. o Normal PAOP in dogs is 5 to 12 mm Hg. o Low PAOP usually signals volumedepletion and the need for fluid administration, whereas increased PAOP is indicative of volume overload or cardiac dysfunction so that additional fluid is contraindicated.

Answer 217

o Right atrial pressures (used in place of CVP), which are measured via the proximal port of the catheter, and cardiac output, which is determined using the thermodilution technique. o Other values that can be calculated include cardiac index (cardiac output ÷ body surface area in square meters), SV (cardiac output ÷ heart rate), SV index (stroke volume ÷ body surface area), SVR ([mean arterial pressure − right atrial pressure] ÷ cardiac index), and pulmonary vascular resistance ([mean PAP − PAOP] ÷ cardiac index). o Some catheters are also equipped with an oximeter that will measure central venous hemoglobin saturation (SvO2). This information, combined with the arterial oxygen saturation (SaO2), allows for determination of the oxygen content of both arterial and mixed venous blood, oxygen delivery, oxygen consumption, and oxygen extraction

Answer 218

Arrhythmias, damage to the tricuspid and pulmonic valves, rupture of a pulmonary artery, and pulmonary thromboembolism have all been reported in humans undergoing the procedure

Answer 219

75% 65% 18%

Answer 220

o Increased venous oxygen extraction and resulting venous desaturation is one of the major compensatory responses to help maintain delivery of oxygen to the peripheral tissues in low flow states. o Measurements of SvO2 and ScvO2 reflect systemic oxygen balance and cumulative oxygen debt.

Answer 221

A recent veterinary study evaluated the use of tissue perfusion parameters as predictors of outcome in dogs with severe sepsis or septic shock. ScvO2 and base deficit were found to be the best discriminators between survivors and nonsurvivors

Answer 222

o Both hemoglobin concentration and SaO2 influence these variables. o ScvO2 is much easier to measure, but there can be a loss of correlation between ScvO2 and SvO2 in very-low-flow states. o If there is an underlying defect in OE, as often occurs in patients with severe sepsis, the SvO2 and ScvO2 values can be normal or even high despite significant oxygen debt.

Answer 223

Decrease in 1mmol/L for each 1mmol/L increase in lactate

Answer 224

No, if we do not know the degree of vasoconstriction CO = BP / SVR If SVR, BP might be normal but CO will decrease and vice versa. BP does not equal to flow.

Answer 225

o The measurement and display of CO2 concentration in the respiratory gases on a monitor. o Maximum inspired and expired carbon dioxide concentrations during a respiratory cycle are displayed.

Answer 226

A graphic display or recording of CO2 concentration versus time or expired volume during a respiratory cycle (carbon dioxide waveform or capnogram)

Answer 227

Capnography o The interpretation of waveforms gives indications on the status of the patient and, in some cases, of the ventilation equipment.

Answer 228

o It can be used to confirm endotracheal tube placement, to assess ventilation and carbon dioxide elimination in a non- invasive manner, and (in combination with blood gas analysis) to estimate alveolar dead-space ventilation. o Capnography has also been used to monitor the efficacy of cardiopulmonary resuscitation.

Answer 229

o Non-diverting (mainstream) and diverting (sidestream). o A nondiverting capnograph measures CO2 directly in the breathing system, whereas a diverting device samples gas from the breathing system and measures the CO2 in that gas in the main unit. o Advantages of mainstream devices include fast response time, no requirement for scavenging gas, ease of calibration (with a sealed chamber containing gas of known carbon dioxide concentration), and use of few disposable items. o Disadvantages include the need to place the sensor near the patient (usually at the endotracheal tube connection); increase in apparatus dead space; potential for leaks, disconnection, or obstructions; potential for the sensor to become dislodged from the chamber; exposure of the sensor to damage; and measurement of CO2 only. o In diverting monitors, the sensor is located in the main unit, remote from the breathing system. o Advantages include minimal added dead space, lightweight patient interface, potential for the measurement of multiple gases, and possibility of use in places where the monitor needs to be remote from the patient. Disadvantages include the potential for sampling problems, delayed response (especially with long sampling tubing), removal of gas at a given rate from the circuit, necessity to scavenge gas, potential for change in gas composition (depending on the technology used), need for calibration gas, and potential for gas mixing in the sampling tubing (especially if the tubing is long).

Answer 230

Infrared absorption, mass spectrometry, and Raman scattering

Answer 231

o This technique is based on the concept that gases that have two or more dissimilar atoms in the molecule have unique and specific absorption spectra of infrared light. o Infrared absorption can therefore be used to measure not only carbon dioxide but also nitrous oxide and the halogenated anesthetics.

Answer 232

Infrared absorption

Answer 233

o Phase 0 corresponds to inspiration, and no carbon dioxide should be measured during that phase. Phase IV is the early part of inspiration, when CO2–free gas starts entering the airway. o Some authors include phase IV in phase 0 or in phase III. o Expiration is divided into the three remaining phases: * I is early expiration, corresponding to the emptying of the anatomic dead space (no carbon dioxide should be measured); * II is a rapidly changing mixture of alveolar and dead-space gas, resulting in a steep increase in measured carbon dioxide concentration; * III is the alveolar plateau, during which alveolar concentration of carbon dioxide is measured. The plateau usually has a slight increasing slope

Answer 234

The end-tidal concentration and is assumed to best represent alveolar CO2 concentration (because gas sampled at that time is almost pure alveolar gas).

Answer 235

o Alveolar partial pressure of carbon dioxide in normal patients is only slightly lower than the arterial partial pressure of carbon dioxide (PaCO2). o Therefore, assuming that no significant respiratory or cardiovascular abnormality is present and that accurate end-tidal measurements are made, capnography allows continuous, noninvasive assessment of PaCO2. o The gradient between end-tidal PCO2 and PaCO2 is normally small (<5 mm Hg in small animal species=

Answer 236

o Increased dead-space ventilation (ventilation of alveoli that are not perfused) increases this gradient. o Increased dead-space ventilation is commonly related to decreased pulmonary blood flow (e.g., pulmonary thromboembolism, low cardiac output); ventilation- perfusion scattering has a similar effect. o In these situations, a larger gradient between end-tidal and PaCO2 may exist, so that end-tidal PCO2 cannot be used to estimate PaCO2 (but changes in end-tidal PCO2 usually still correlate with changes in PaCO2)

Answer 237

During mechanical ventilation

Answer 238

o Although arterial blood gas analysis remains the gold standard to assess ventilation, capnography has two major advantages: it provides continuous versus intermittent monitoring, and it is not invasive. o It is the only tool used clinically in animals that gives a continuous estimate of PaCO2.

Answer 239

o Increased apparatus dead space, rebreathing with a circle system (e.g., faulty unidirectional valve, exhausted carbon dioxide absorbent), and rebreathing with a nonrebreathing system (inadequate fresh gas flow, leak or disconnection of the inner tubing of a Bain circuit) all result in an elevated baseline, increased inspired PCO2 and, if ventilation does not change, increased end-tidal PCO2. o The end-tidal to PaCO2 gradient will be normal or decreased. o The slope of phase IV usually is decreased.

Answer 240

Usually results in low, nonzero end-tidal readings

Answer 241

o Changes in CO2 production without associated changes in alveolar ventilation result in changes in end-tidal PCO2, with a normal waveform, no inspired carbon dioxide, and a normal end- tidal to PaCO2 gradient. o Common causes of increased carbon dioxide production (and increased end-tidal PCO2) include pain, anxiety, shivering, seizures, hyperthermia, administration of sodium bicarbonate, and CO2 absorption from the peritoneal cavity during laparoscopy.

Answer 242

o Leads to a decrease in end-tidal PCO2, with an otherwise normal waveform, no inspired carbon dioxide, and a normal end- tidal to arterial gradient. o Hypoventilation leads to opposite changes. Upper airway obstruction results in changes similar to those described for equipment obstruction (decrease in the slope of phase II, an increase in the slope of phase III, and sometimes a decrease in end-tidal PCO2).

Answer 243

o Decreased transport of CO2 to the lungs (e.g., decreased cardiac output, pulmonary thromboembolism) results in decreased end-tidal PCO2, a normal capnogram, no inspired carbon dioxide, and an increased end-tidal to PaCO2 gradient. o Cardiac arrest results in a sudden decrease of end-tidal PCO2 to zero or near-zero values. o Capnography can be used to monitor the efficiency of CPR by observing the return of CO2 in the expired gas (related to the return of pulmonary blood flow). o End-tidal CO2 values during cardiopulmonary resuscitation have been reported to correlate with resuscitation success (the higher the values, the better the chances of successful resuscitation).

Answer 244

o These are small oscillations in phase IV. o The slope of this downstroke is also decreased. o The frequency of these oscillations corresponds to heart rate. o Cardiogenic oscillations are due to gas movement in the airway caused by the heart beat

Answer 245

Bronchoconstriction (asthma, bronchospasm) is a typical cause of prolonged expiration (phases II and III) and a decreased slope of phase II and increased slope of phase III. Same as airway obstruction (patient or tube)

Answer 246

Is a decrease in carbon dioxide concentration during the alveolar plateau. This is due to a spontaneous inspiratory effort in mechanically ventilated patients

Answer 247

Metabolism, circulation and ventilation o Both metabolism and ventilation will move in the same direction -> if a metabolic condition causes increases in CO2 production, the ETCO2 will also increase, and vice versa.

Answer 248

TRUE o Nevertheless, the consequences of ischemia and reperfusion share many phenotypic parallels with activation of a host immune response directed toward invading microorganism.

Answer 249

o Ligand binding to TLRs leads to the activation of downstream signaling pathways, including NF-kB, MAPK and type I interferon pathways, resulting in the induction of proinflammatory cytokines and chemokines. o These receptors can also be activated by endogenous molecules in the absence of microbial compounds (DAMPs), particularly in the context of cell damage or death, as occurs during ischemia and reperfusion. o DAMPs -> many of these ligands (for example, high-mobility group box 1 (HMGB1) protein or ATP) are normally sequestered intracellularly; upon tissue damage, they are released into the extracellular cell death compartment where they can activate an immune response.

Answer 250

o Both extracranial and intracranial priorities must be considered. o Identification of life- threatening extracranial injuries such as hemorrhage, penetrating thoracic or abdominal wounds, airway obstruction, and compromised oxygenation, ventilation, or volume status is of paramount importance. o Once life-threatening extracranial factors have been addressed, intracranial priorities should include maintenance of adequate cerebral perfusion pressure (CPP), ensuring adequate oxygen delivery to the brain, and treatment of acute intracranial hypertension, as well as continued monitoring of neurologic status.

Answer 251

o Primary injury occurs as an immediate result of the traumatic event. o Secondary injury occurs during the hours to days after trauma and is caused by a complex series of biochemical events, including release of inflammatory mediators and excitatory neurotransmitters, and changes in cellular membrane permeability.

Answer 252

o Concussion o Contusion o Laceration

Answer 253

o The least severe primary brain injury is concussion, characterized by a brief loss of consciousness. o Concussion is not associated with an underlying histopathologic lesion.

Answer 254

o Brain contusion consists of parenchymal hemorrhage and edema and clinical signs can range from mild to severe. o Contusions can occur in the brain directly under the site of impact (“coup” lesions), in the opposite hemisphere (“contrecoup” lesions), or both, as a result of displacement of the brain within the skull. o Although mild contusions can be difficult to differentiate from a concussion, unconsciousness for more than several minutes is most consistent with contusion.

Answer 255

o The most severe type of primary brain injury and is characterized by physical disruption of the brain parenchyma. o Axial hematomas within the brain parenchyma and extraaxial hematomas in the subarachnoid, subdural, and epidural spaces can occur, causing compression of the brain and leading to severe localizing signs or diffuse neurologic dysfunction.

Answer 256

o Immediately after brain injury there is massive release of excitatory neurotransmitters that causes influx of sodium and calcium into neurons, resulting in depolarization and further release of excitatory neurotransmitters. o Increased influx of calcium overwhelms mechanisms for removal, causing severe intracellular damage and ultimately neuronal cell death. o Excessive metabolic activity also results in depletion of adenosine triphosphate (ATP) stores in the brain. o Several factors favor the production of ROS after TBI, including hypoperfusion and local tissue acidosis. o Hemorrhage provides a source of iron, which favors the production of hydroxyl radicals. Catecholamines may also contribute to the production of free radicals by direct and indirect mechanisms. o These ROS then oxidize lipids, proteins, and deoxyribonucleic acid (DNA), resulting in further destruction of neurons. Because the brain provides a lipid-rich environment, it is particularly susceptible to oxidative injury. o Nitric oxide has been associated with perpetuation of secondary brain injury after trauma, most likely because of its vasodilatory effects and its participation in free radical reactions. Exact mechanism is not well understood.

Answer 257

o TBI is associated with production of inflammatory mediators. o These mediators perpetuate secondary brain injury via a number of mechanisms, including inducing NO production, triggering influx of inflammatory cells, activating the arachidonic acid and coagulation cascades, and disrupting the blood-brain barrier. o Primary and secondary intracranial injuries, in combination with systemic effects of the trauma, ultimately result in worsening of cerebral injury as a result of a compromised CPP, the force driving blood into the calvarium and providing the brain with essential oxygen and nutrients.

Answer 258

CPP is defined as the difference between MAP and ICP.

Answer 259

o Blood flow to the brain per unit of time. o It is a function of CPP and cerebrovascular resistance

Answer 260

o The normal brain is capable of maintaining a constant CBF over a wide range of MAP (50 to 150 mm Hg) via autoregulatory mechanisms. o However, the traumatized brain often loses much of this autoregulatory capacity, making it susceptible to ischemic injury with even small decreases in MAP.

Answer 261

o Vintracranial = Vbrain + VCSF + Vblood + Vmass lesion o V = volume. o Sudden increases in any of these volumes as a result of primary and secondary brain injuries can lead to dramatic increases in ICP. o Initially, increases in ICP will trigger the Cushing’s reflex, or central nervous system (CNS) ischemic response, a characteristic rise in MAP and reflex decrease in heart rate. o The CNS ischemic response in a patient with head trauma is a sign of a potentially life-threatening increase in ICP and should be treated promptly.

Answer 262

o Initial neurologic examination should focus on the level of consciousness, posture, and pupil size and response to light. o A more detailed neurologic examination can be performed once stabilizing therapy has been instituted. o Based on findings from this examination, a numeric score can be assigned to grade the severity of injury using the modified Glasgow Coma Scale, a system developed for animals with head injuries. o The initial neurologic examination should be interpreted in light of the cardiovascular and respiratory system because shock can have a significant effect on neurologic status, reducing the patient’s level of consciousness and pupillary responses.

Answer 263

FALSE - it should be avoided because occlusion of the jugular vein can result in marked increases in ICP as a result of decreased venous outflow from the brain.

Answer 264

o MAP should be maintained at or above 80mmHg in order to maintain CPP. o Blood pressure as measured with the Doppler technique should be maintained above 100 mm Hg. o Heart rate should be assessed when hypertension (MAP > 120 mm Hg or systolic > 140 mm Hg) is present. o If evidence of the central nervous system ischemic response is present, therapy directed toward lowering ICP should be instituted. o Alternatively, hypertension associated with tachycardia suggests pain or anxiety, which should be treated as indicated.

Answer 265

2 to 5 mm Hg

Answer 266

Radiographs of the skull in patients that have sustained head trauma are an insensitive diagnostic tool and rarely provide valuable information.

Answer 267

o CT is the preferred imaging method. o CT scans are superior to MRI for assessing bone and areas of acute hemorrhage or edema. o As the time from injury increases, or when subtle neurologic deficits are present, MRI becomes a more useful tool. o Advanced imaging provides information about mass lesions (epidural, subdural, or intra- parenchymal hemorrhage) or depressed skull fractures that may require surgical intervention.

Answer 268

Treatment of intracranial hypertension and control of cerebral metabolic rate.

Answer 269

o Increases in the blood CO2 concentration can lead to cerebral vasodilation and increased intracranial blood volume, worsening ICP. o Conversely, hypocapnia caused by hyperventilationcan lead to cerebral vasoconstriction, decreasing cerebral blood flow and leading to cerebral ischemia. o Therefore CO2 should be maintained at the low end of the normal range in patients with head trauma (venous CO2 40 to 45 mm Hg, arterial CO2 35 to 40 mm Hg). In some patients this will require mechanical ventilation

Answer 270

o If they don't have electrolyte disturbances, 0.9% NaCl o It contains the smallest amount of free water (sodium concentration 154 mEq/L) of the isotonic fluids and is therefore least likely to contribute to cerebral edema. o For hydrated patients with evidence of hypovolemia and increased ICP, a combination colloid and hyperosmotic (hypertonic saline) solution is recommended. o Patients that do not respond to volume resuscitation require vasopressor support.

Answer 271

o Mannitol has been shown to decrease ICP, increase CPP and CBF, and have a beneficial effect on neurologic outcome in patients with head injury. o Mannitol also possess free radical scavenging properties. Its positive effects can be seen clinically within minutes of administration, most likely a result of its rheologic its effects (decreased blood viscosity) causing an increase in CBF and cerebral oxygen delivery. o Within 15 to 30 minutes, its osmotic effects predominate, drawing water out of the brain parenchyma (primarily normal tissue) and into the intravascular space. These effects can last from 1.5 to 6h. o In humans, mannitol may induce AKAI if serum osmolarity exceeds 320 mOsm/L -> serial measurement of serum osmolality may be useful in patients receiving repeated doses. o Mannitol may cause increased permeability of the blood-brain barrier, allowing it to leak into the brain parenchyma where it can exacerbate edema. Because this effect is most pronounced when mannitol remains in the circulation for long periods, the drug should be administered as repeated boluses rather than as a constant rate infusion. o Mannitol boluses of 0.5 to 1.5 g/kg have been recommended for the treatment of increased ICP in dogs and cats. Treatment must be followed with isotonic crystalloid or colloid solutions, or both, to maintain intravascular volume.

Answer 272

o Hypertonic saline is an alternative hyperosmotic solution that may have advantages over mannitol in some patients with head injury. o Because sodium does not freely cross the blood-brain barrier, hypertonic saline has similar rheologic and osmotic effects to mannitol. o In addition, it improves hemodynamic status and has beneficial vasoregulatory and immunomodulatory effects. o Because sodium is redistributed within the body and reabsorbed in the kidneys, hypo- tension is a less likely sequela than with mannitol, making it a better choice for patients with increased ICP and systemic hypotension. o Hypertonic saline can be administered with a colloid in such cases to allow for a more prolonged volume expansion effect.

Answer 273

o A clinical trial evaluating more than 10,000 human adults with head injury showed that corticosteroid treatment was associated with worse outcomes at 2 weeks and 6 months after injury. o The Brain Trauma Foundation recommends against corticosteroid administration in patients with TBI.

Answer 274

o Furosemide has been used in patients with head trauma either as a sole agent to reduce cerebral edema or in combination with mannitol to decrease the initial increase in intravascular volume and hydrostatic pressure associated with the drug. o However, the use of this drug as a sole agent in patients with head trauma has been called into question because of the potential for intravascular volume depletion and systemic hypotension, leading to decreased CPP. o The Brain Trauma Foundation guidelines do not recommend the administration of furosemide in combination with mannitol. o Therefore it should be reserved for those patients in whom it is indicated for reasons other than cerebral edema, such as those with pulmonary edema or oligoanuric renal failure.

Answer 275

o Techniques to decrease cerebral blood volume (CBV) have been proposed as methods for lowering increased ICP. o Elevation of the head by 15 to 30 degrees reduces CBV by increasing venous drainage, decreasing ICP, and increasing CPP without deleterious changes in cerebral oxygenation. o A slant board should be used instead of pillows or towels to prevent occlusion of the jugular veins by bending of the neck. Higher elevations of the head may cause a detrimental decrease in CPP. o Prevention of hypoventilation, as described earlier, can reduce cerebral vasodilation and decrease CBV; the goal should be normocapnia (arterial carbon dioxide of 35 to 40 mm Hg). o In animals with acute intracranial hypertension, short-term hyperventilation to an arterial carbon dioxide of 25 to 35 mm Hg may be used to reduce CBV and ICP, but long-term hyperventilation is not recommended based on evidence that the decrease in CBF leads to cerebral ischemia and worsens outcome.

Answer 276

o Post-TBI seizures are common in people, occurring within 3 years in 4.4% of patients with mild TBI, 7.6% of patients with moderate TBI, and 13.6% of patients with severe TBI in one study. o Veterinary studies have documented a similar phenomenon, with seizure rates of 6.8% in dogs and 0% in cats (although the 95% confidence interval was 0% to 5.6%). o Unfortunately, prophylactic anticonvulsant therapy has not been shown to reduce development of delayed seizures after TBI in people. o However, aggressive treatment of seizures while animals are hospitalized is recommended.

Answer 277

o Excitotoxicity is a complex process triggered by glutamate receptor activation that results in the degeneration of dendrites and cell death. o All subcellular compartments are affected by the excitotoxic process, with changes in the cytosol, mitochondria, endoplasmic reticulum, and nucleus. o Normal amounts of glutamate receptor activation can damage neurons under conditions of metabolic and oxidative stress, which occur after a stroke or traumatic brain injury or in age-related neurodegenerative disorders. o Excitotoxicity is triggered by the overactivation of glutamate receptors, resulting in Na+ and Ca2+ influx across through the plasma membrane as the result of opening of glutamate receptor channels and voltage-dependent Ca2+ channels. o In addition, the activation of GTP-binding protein-coupled metabotropic glutamate receptors stimulates inositol trisphosphate (IP3) production and the release of Ca2+ from the ER.

Answer 278

o Because of excitotoxicity and inflammation. o Can lead to cerebral ischemia and cellular swelling, thus increasing ICP.

Answer 279

The Brain Trauma Foundation states that there is insufficient evidence to publish treatment standards on the use of barbiturates, but this therapy may be considered in patients with elevated ICP that is refractory to medical and surgical therapy.

Answer 280

o Although the initial neurologic status may be helpful in predicting outcome, reassessment after stabilizing therapy is recommended because the level of consciousness may improve once tissue perfusion has been corrected. o Pupillary dilation, loss of pupillary light responses, and deterioration in the level of consciousness during therapy are poor prognostic indicators. o It is likely that younger animals, particularly kittens, can make remarkable recoveries despite severe dysfunction immediately after trauma, although definitive research is lacking. o Owners should be aware that animals that survive severe TBI may have persistent neurologic deficits for an indefinite period. These animals can also develop delayed seizure disorders. o The Small Animal Coma Scale (mGCS) was developed to quantitatively assess functional impact of brain injury. This scale assesses three major categories: motor activity, level of consciousness, and brainstem reflexes. o Although this scale has not been validated prospectively in animals, it has been shown retrospectively to correlate with 48h outcome in dogs with TBI. This may be most useful when evaluated serially in patients to determine if there has been improvement or deterioration after treatment. o In human medicine, hyperglycemia at admission and persistence of hyperglycemia have been associated with worsened mortality and outcome. o Hyperglycemia has been associated with more severe injury in TBI veterinary patients but has not been validated as an independent predictor of outcome.

Answer 281

Blunt and penetrating

Answer 282

o Vehicular trauma o High-rise falls o Human malicious activities

Answer 283

o Common chest injuries included pulmonary contusions (58%), pneumothorax (47%), hemothorax (18%), and rib fractures (14%) o Common abdominal injuries included hemoperitoneum (23%), abdominal hernias (5%), and urinary tract ruptures (3%)

Answer 284

o The liver was the abdominal organ most often damaged (31% of the abdominal organ injuries), with injuries ranging from fissures of the capsule or parenchyma to fragmentation of a hepatic lobe. o Other commonly injured organs included the urinary bladder, diaphragm, and kidney

Answer 285

Three stories Three stories

Answer 286

o In a study evaluating high-rise falls in 119 cats, approximately 34% were noted to have thoracic trauma. o Pneumothorax and pulmonary contusions were regularly diagnosed, being documented in 60% and 40% of cats with thoracic trauma, respectively. o Additionally, hemothorax was diagnosed in 10% of cats. Although injury to the chest and bones was common, nearly 97% of cats survived the fall. o Falls from the seventh story or higher were more likely to result in thoracic trauma. o Abdominal injuries were uncommon in this cohort of cats, and the authors hypothesized that this was secondary to the forelimbs absorbing the impact of the landing.

Answer 287

o Unfortunately, human abuse of companion animals is another cause of blunt trauma. o In a study investigating intentional injury to animals, internal injury to the abdomen was documented less often than superficial injuries or fractures. o However, 13 of 217 (6%) dogs in this study experienced rupture of an organ, including spleen, liver, bladder, and kidney. o Cats tended to experience abdominal muscle rupture. Kicking of the animal was the cause of the abdominal injury in most cases

Answer 288

o Bite wounds o Also reports on missile injuries, impalement/stab injuries and evisceration

Answer 289

o The thorax is the body region most likely to experience trauma from a bite wound in dogs. o It is second only to the back region in cats.

Answer 290

FALSE o Wounds that do not appear to penetrate the thorax or abdomen still often require surgical exploration because bacteria from the biting animal’s mouth or environment will likely contaminate the wound and result in abscess formation. o Additionally, it may not always be obvious if a wound has entered a body cavity.

Answer 291

o Bleeding often occurs secondary to trauma, and this can be reflected in the red blood cell count; animals may be anemic on presentation depending on the severity of trauma and the amount of time since the traumatic event. o Leukocytosis (specifically neutrophilia) can be increased secondary to stress, inflammation, or infection, all of which may occur with trauma. o Thrombocytopenia secondary to consumption of platelets with bleeding may also be encountered.

Answer 292

o A biochemistry panel should be evaluated, with particular attention paid to the liver and renal values as well as the electrolyte and acid-base balance. o Alanine aminotransaminase (ALT) and aspartate transaminase (AST) can be increased when liver trauma has occurred. In cases of biliary trauma and subsequent bile leakage, increases in alkaline phosphatase (ALP), γ-glutamyl transferase (GGT), and bilirubin are often present. o Abnormalities of electrolytes may be seen secondary to clinical signs such as vomiting or anorexia or because of specific conditions such as uroabdomen. o Similarly, azotemia is often noted in animals with a uroabdomen or those suffering from dehydration or acute kidney injury. Measurement of urine specific gravity before fluid therapy may help assess renal function.

Answer 293

o Chest radiographs are essential for several reasons. When an abdominal trauma has occurred, the chest radiographs may reveal a diaphragmatic rupture or body wall herniation; herniation of organs such as stomach and intestine may be life threatening. o Additionally, pneumothorax, pleural effusion, and pulmonary contusions can be detected with chest radiographs. Some injuries to the skin and subcutaneous tissue can be severe enough that a flail chest may not be noted. o Chest radiographs often help to assess for the presence of rib fractures.

Answer 294

o Abdominal radiographs are useful in the diagnosis of intraabdominal pathologic conditions, but identifying a specific diagnosis may not always be possible. o The presence of intra-abdominal gas suggests that abdominal wall penetration or organ perforation has occurred and requires immediate attention. o The general loss of serosal detail in the abdomen is suggestive of the presence of fluid in the peritoneal space, retroperitoneal space, or both. o Animals with traumatic pancreatitis or very young or thin animals may also have poor serosal detail on radiographs.

Answer 295

o Diaphragmatic and body wall ruptures are commonly diagnosed with radiographs. o Both thoracic and abdominal radiographs should be taken in suspected cases of diaphragmatic rupture. o Characteristic changes seen on radiographs in animals with a diaphragmatic rupture include loss of continuity of the diaphragm, loss of intrathoracic detail (specifically cardiac silhouette), and the presence of gas-filled bowel loops or a mass effect in the thorax. o These changes are not always present, and further imaging may be necessary to confirm the diagnosis.

Answer 296

With ultrasonography

Answer 297

o Several analyses should be performed on the fluid sample, including hematocrit, total solids, bilirubin, creatinine, potassium, and glucose. o Other potential tests may include PaO2, CO2, lactate, amylase, and lipase. In addition, a slide of the sample should be obtained for cytologic examination.

Answer 298

o The presence of red blood cells in an abdominal effusion does not necessarily confirm a hemoperitoneum. o With a true hemoperitoneum, red blood cells are usually observed within macrophages, signifying erythrophagocytosis (although this may not be present in the acute stages). o Hemosiderin from the broken down red blood cells usually fills the cytoplasm of the involved phagocyte. o Alternatively, if the packed cell volume (PCV) of the fluid is increasing or nears the PCV found in the peripheral blood, ongoing hemorrhage should be suspected. o Another guideline is that the fluid PCV should be at least 10% to 25% of the peripheral blood PCV to be considered a hemorrhagic effusion.

Answer 299

1 : 2 1 : 1.9

Answer 300

100% 1.4 : 1

Answer 301

FALSE Greater than 100mg/dL Modified transudates

Answer 302

o Antimicrobial therapy may be indicated in trauma cases depending on the organ that is traumatized and the extent of injury to the skin, subcutaneous tissue, and muscles. o If a penetrating injury has occurred, antimicrobials should be initiated; all wounds should be cultured and broad-spectrum antimicrobials administered pending the results of the susceptibility. o For cases of bowel perforation and pyothorax, antimicrobial therapy should be started immediately with broad-spectrum drugs that also have anaerobic coverage.

Answer 303

o In the initial treatment of these patients, it is essential to treat hemorrhagic shock and improve perfusion by administering isotonic crystalloids (up to 50 ml/kg in cats and 90 ml/kg in dogs) or synthetic colloids (5 to 20 ml/kg). o “Hypotensive resuscitation” to a MAP of 60mmHg or SBP of 90mmHg may prevent excessive bleeding or disruption of clot formation and function. o Some animals may also require the use of blood transfusions during the resuscitation period (i.e., whole blood, packed red blood cells, and plasma). o Animals that are unresponsive to crystalloid and synthetic colloid fluid resuscitation and have evidence of severe hemorrhage should be given fresh whole blood or packed red blood cells and fresh frozen plasma in an attempt to stabilize the clinical signs of shock, maintain the hematocrit above 25%, and sustain the clotting times within the normal range. o pRBCs and FFP are administered at a dose of 10 to 15 ml/kg and fresh whole blood at a dose of 20 to 25 ml/kg (a blood type and crossmatch should be performed if possible).

Answer 304

o Although the injuries that are present in the thorax and abdomen often require emergency consideration, any entry wounds should be evaluated closely. o Sterile lubricating jelly can be placed in the wound in an attempt to keep the wound clean before clipping and anesthetic preparation. o As soon as the patient is stable, fur should be removed from the wound area and the skin surrounding the wound. Any obvious foreign material should be removed and the wounds flushed with sterile saline. o It is essential that bite wounds be explored for the presence of more severe disease deeper to the externally located punctures. o When a dog or cat sustains bite wounds, there is commonly tearing of the underlying tissue and elevation of the skin away from the body wall. o Drains are usually required to address these wounds because fluid accumulation in these regions is common; when fluid is left to accumulate, abscess formation is more likely to occur.

Answer 305

o Trauma is the most common cause of diaphragmatic ruptures in small animals. o Therefore a diaphragmatic rupture should be suspected in any dog or cat with respiratory distress after a traumatic event. Furthermore, other obvious clinical lesions may not be present in 48% of cases of traumatic diaphragmatic ruptures. o These animals may have signs of shock upon presentation, and early stabilization and oxygen therapy should be initiated. o After stabilization, surgery is indicated to repair the rupture. If any gastrointestinal organs are displaced into the thoracic cavity or respiratory stability is unachievable, surgery is indicated on an emergency basis. o The outcome associated with surgical intervention is good, with an approximate 90% perioperative survival rate in dogs and cats treated on an acute or chronic basis.

Answer 306

TRUE o The injury causing the development of an abdominal rupture will likely also result in additional trauma to the intra-abdominal organs and treatment of myriad injuries may be indicated. A full abdominal exploration should be performed to evaluate all intra-abdominal organs for injury or compromise.

Answer 307

o Body wall ruptures are generally surgical emergencies, especially if caused by bite wounds. o Organs can be entrapped in the defect, resulting in strangulation and rapid demise of the patient. Intestines have been reported to be displaced through the rupture in as many as 54% of cases and often require a R&A because of devitalized tissue. o Other organs commonly displaced include the omentum, liver, and urinary bladder. o In one study 73% of dogs and 80% of cats survived to discharge from the hospital after surgical repair of a body wall rupture.

Answer 308

o Chylothorax is characterized by the accumulation of a chylous effusion (consisting of triglycerides and mononuclear cells) in the thorax. o Although the cause of chylothorax in the majority of animals is unknown, and therefore labeled as idiopathic, trauma has been documented to cause chylothorax. o Clinical signs of chylothorax are generally nonspecific (e.g., lethargy, weight loss, anorexia) or related to the respiratory system (e.g., coughing, exercise intolerance, respiratory distress). o Most recommendations for treatment of chylothorax include a combination of the following potential surgical options: thoracic duct ligation, pericardectomy, omentalization of the thoracic cavity, and cisterna chyli ablation. Less invasive options (via thoracoscopy and interventional radiology) are developing and early results are promising. o Chylous ascites has been documented in both dogs and cats, but a traumatic etiology has not been noted

Answer 309

o Pyothorax, an inflammatory exudate in the pleural cavity, is generally septic. o As with most disease affecting the pleural cavity, the clinical signs often associated with pyothorax include respiratory distress and tachypnea; pyrexia is diagnosed in approximately half of animals with a pyothorax. o In a recent study, 4 of 10 animals with pyothorax were suspected to be secondary to trauma. It is difficult to determine the inciting cause in many cases of pyothorax, so the true incidence of traumatically induced pyothorax is unknown. o Both medical and surgical treatment of pyothorax may be indicated. o Medical management often consists of bilateral thoracostomy tube placement, intravenous antimicrobials, and, potentially, intrapleural lavage. In order to determine the origin of a pyothorax and plan the best surgical approach, advanced imaging with CT is recommended.

Answer 310

o Gunshot wounds, bite wounds, and vehicular trauma to the abdomen can result in septic peritonitis either from direct contamination with bacteria or leakage from an intra-abdominal organ. o In a retrospective canine study evaluating gunshot and bite wounds to the abdomen, peritonitis was noted in 40% of the dogs with gunshot wounds and 14% of the dogs with bite wounds. o Another study in cats found that 16% of cases of septic peritonitis occurred secondary to trauma (gunshot wounds, bite wounds, and motor vehicle trauma). o Animals presenting with septic peritonitis often present in shock and have a palpable abdominal effusion. Initial treatment should target the cardiovascular and respiratory systems. Fluid resuscitation and broad-spectrum antimicrobial therapy are essential. o When the patient has been stabilized, surgical exploration should be performed and the inciting cause must be found and eliminated. Postoperative management with either open abdominal drainage or primary closure with closed-suction drains should be performed. o If drains are placed, the amount of effusion produced should be monitored and recorded every 2 to 6 hours. Cytology of the fluid should be checked regularly to monitor for evidence of recurrence of a septic effusion or a secondary infection.

Answer 311

o Leakage of bile from the gallbladder or biliary ducts can occur secondary to blunt or penetrating abdominal trauma. o It is reportedly more common for blunt trauma to result in ductal rupture than gallbladder rupture, usually just distal to the last hepatic duct. o Bile leakage should be addressed surgically as soon as possible -> bile in the peritoneal cavity can cause severe peritonitis because bile acids are toxic to most living tissues. o In addition, many biliary effusions are septic and may prove life threatening. Appropriate antimicrobial therapy and supportive care are vital.

Answer 312

o After initial stabilization, the decision to manage these cases conservatively (medically) or surgically must be made. o External counter- pressure can be attempted for control of abdominal hemorrhage via the placement of an abdominal bandage; the use of external counterpressure in stabilizing blood pressure and improving survival has been advocated. o Other conservative management options include internal counterpressure and autotransfusion. o The decision to perform surgery is case dependent, but if a patient is not responding to fluid resuscitation efforts, has a rising intra-abdominal PCV, or is continuing to effuse based on ultrasonographic evaluation or physical examination, surgery should be performed. o In a retrospective study evaluating cases of traumatic hemoperitoneum, the spleen, liver, and kidney were bleeding in 58%, 50%, and 23% of cases, respectively (determined during surgery or necropsy). Of the 28 cases evaluated in that study, 9 underwent exploratory laparotomy; 4 cases survived to discharge, 2 died, and 3 were euthanized. o Discounting the euthanized cases, the mortality rate for the animals managed surgically was 33% and the mortality rate for the cases managed medically was 25%

Answer 313

o After rupture of the urinary tract, urine can accumulate both in the peritoneal space and in the retroperitoneal space, depending on the location of rupture. o If trauma to the distal urethra is severe enough, urine can also be noted in the perineal region.

Answer 314

o Dogs and cats with urine leakage often are presented azotemic, and these cases should be stabilized as much as possible before undergoing anesthesia or pursuing surgery. o Additionally, severe electrolyte abnormalities (in particular, hyperkalemia) can cause arrhythmias, further compromising a patient that is already a high anesthetic risk. o Characteristic ECG abnormalities noted in cases of hyperkalemia may include tall, tented T waves, absence of P waves, and bradycardia. If not addressed immediately, this can become life threatening. o Medical management may include the administration of drugs such as calcium gluconate, insulin/glucose, bicarbonate, or β agonist therapy

Answer 315

o Definitive surgical treatment for cases of uroperitoneum secondary to renal or ureteral injury is generally necessary for a successful outcome and may result in an ureteronephrectomy. o Bladder ruptures often require surgical correction, although small leaks may heal with the placement of a urinary catheter and collection system for continuous decompression. o Surgical correction is typically accomplished by placing sutures over the rupture site. Bladder resection may be necessary if the bladder tissue appears severely damaged. o Urethral trauma is managed conservatively in some cases by placing a urethral catheter or a cystostomy tube. o If conservative management is unsuccessful, surgical closure of the urethral defect is necessary. Postoperative supportive care and intensive monitoring is important in these animals to ensure a positive outcome. Fluid therapy and urine output must be closely monitored and cessation of azotemia is expected if the injury has been properly addressed.

Answer 316

o Head trauma, cranium fractures, recumbency at admission, hematochezia, suspicion of ARDS, disseminated intravascular coagulation, multiorgan dysfunction syndrome, development of pneumonia, positive pressure ventilation, vasopressor use, and CPA. o Ionized hypocalcemia were significantly more likely to require therapy with oxygen, colloids, blood products, and vasopressors and spent significantly longer in the hospital and intensive care unit than dogs without hypocalcemia. Dogs with ionized hypocalcemia also had a higher mortality rate.

Answer 317

o The animal trauma triage (ATT) scoring system has been created to aid in the assessment of veterinary trauma patients. o The score is based on an assessment of six categories, including perfusion, cardiac, respiratory, eye/muscle/integument, skeletal, and neurologic status; a score of 0 to 3 is given to each category with 0 indicating slight or no injury and 3 indicating severe injury (highest possible score would be 18). o In a study, the mean ATT was significantly lower for survivors than nonsurvivors. This finding was corroborated in a more recent study evaluating animals involved in motor vehicle accidents.

Answer 318

o Clean: atraumatic, surgically created under aseptic conditions (incisions) o Clean contaminated: minor break in aseptic surgical technique (controlled entry into the gastrointestinal [GI], urogenital, or respiratory tracts) in which the contamination is minimal and easily removed. o Contaminated: recent wound related to trauma with bacterial contamination from street, soil, or oral cavity (shearing or bite wound); can also be a surgical wound with major breaks in asepsis (spillage from the GI or urogenital tracts) o Dirty or infected: older wound with exudate or obvious infection (abscess in a bite wound, puncture wound, or traumatic wound with retained devitalized tissue); contains more than 105 organisms per gram of tissue.

Answer 319

o Grade I: Small break in the skin caused by the bone penetrating through o Grade II: Soft tissue trauma contiguous with the fracture, often caused by external trauma (e.g., bite wound, low-velocity gunshot injuries) o Grade III: Extensive soft tissue injury, commonly in addition to a high degree of comminution of the bone (e.g., distal extremity shearing wounds, high-velocity gunshot injuries)

Answer 320

o Initial care of the soft tissues should not be delayed if a surgeon is not immediately available or if the patient is not stable enough to undergo general anesthesia for several hours. o Any exposed bone should be covered with sterile lubricating jelly and a sterile bandage but should not be pushed back below the skin surface because this can cause deeper contamination of the wound or further injury to the tissues. o Similar guidelines exist for wounds with penetrating foreign bodies such as arrows, large wooden splinters, or knives. The foreign body may be tamponading a large vessel, and removal could lead to severe hemorrhage. These objects should be removed only under controlled surgical conditions.

Answer 321

1) Inflammation 2) Debridement 3) Repair/proliferation 4) Maturation The phases overlap and the transitions are not visible to the naked eye.

Answer 322

o The inflammatory phase occurs during the first 5 days after injury. o Immediately after trauma there is hemorrhage caused by disruption of blood vessels, and then vasoconstriction and platelet aggregation limit the bleeding. o Vasodilation follows within 5 to 10 minutes, allowing fibrinogen and clotting elements to leak from the plasma into the wound to form a clot and eventually a scab. o The clot serves as scaffolding for invading cells such as neutrophils, monocytes, fibroblasts, and endothelial cells. o Also contained in the plasma are inflammatory mediators (cytokines) such as histamine, prostaglandins, leukotrienes, complement, and growth factors

Answer 323

o The debridement phase occurs almost simultaneously with the inflammatory phase. o It is marked by the entry of white blood cells into the wound. Neutrophils are the first to appear in the wound approximately 6 hours after injury. They remove extracellular debris via enzyme release and phagocytosis. o Monocytes appear approximately 12 hours after trauma, and they become macrophages within 24 to 48 hours. The monocytes stimulate fibroblastic activity, collagen synthesis, and angiogenesis. Macrophages remove necrotic tissue, bacteria, and foreign material.

Answer 324

o The repair phase, also called the proliferative phase, begins 3 to 5 days after injury and lasts about 2 to 4 weeks. o This is the most dramatic healing phase and is characterized by angiogenesis, granulation tissue formation, and epithelialization. o Fibroblasts proliferate and start synthesizing collagen, and then capillary beds grow in to form granulation tissue. o Granulation tissue provides a surface for epithelialization and is a source of myofibroblasts that play a role in wound contraction. o New epithelium is visible 4 to 5 days after injury and occurs faster in a moist environment. Wound contraction is first noticeable by 5 to 9 days after injury and continues into the maturation phase.

Answer 325

o The maturation phase occurs once adequate collagen deposition is present and is marked by wound contraction and remodeling of the collagen fiber bundles. o It starts at about 17 to 20 days after injury and may continue for several years. o Healed wounds are never as strong as the normal tissue; a scar is only about 80% as strong as the original tissue.

Answer 326

o Direct pressure should be applied to any bleeding wounds. o If bleeding cannot be controlled by direct pressure, emergent surgical intervention is required. o Bleeding from appendages can be controlled with tourniquets by using a pneumatic blood pressure cuff inflated to 200mmHg for up to 1 hour. o Wounds should be kept clean and moist and protected from the hospital environment. o A sterile, water-soluble lubricant and saline-soaked sponges can be applied to the wounds initially and then covered with a sterile towel and soft padded bandage if the patient must be moved. o It is important that the damaged tissue remain moist because desiccation impairs wound healing.

Answer 327

o To create a healthy wound bed with a good blood supply that is free of necrotic tissue and infection in order to promote healing. o Most wounds will require daily debridement and bandage changes, and the clinician should not be discouraged if the wound cannot be closed initially.

Answer 328

1. Assess need for or response to antimicrobial therapy. 2. Debride, removing necrotic tissue, and then lavage the wound. 3. Determine if the wound can be closed. 4. Protect the wound with a bandage, Elizabethan collar, or both.

Answer 329

o Local anesthetics are ideal in unstable patients that cannot tolerate general anesthesia but have significant injuries to the limbs. o Pelvic limbs can be debrided using epidural analgesia. o Thoracic limb wounds can be debrided using a brachial plexus block.

Answer 330

o Sterile lubricating jelly should be applied to the exposed wound to protect it from further contamination and a wide area of fur clipped from the skin around the wound. o Gross dirt from the skin around the wound should be cleaned by applying surgical scrub solution (chlorhexidine or povidone-iodine) to unbroken skin, but not to the surface of the wound because these solutions are damaging to exposed tissues.

Answer 331

o Done using aseptic technique: sterile gloves, sterile gown, and cap and mask, and the wound should be draped with sterile towels or water-impermeable drapes. o At the time of initial assessment and subsequent bandage changes, necrotic tissue should be excised. o All bite wounds should be explored, even if they look minor, because teeth exert a macerating or crushing force that can damage tissues deep below the skin surface. The hole around the bite wound should be trimmed and then tented up to evaluate the subcutaneous tissues. A probe, such as a mosquito or Kelly forceps, can be used to assess for dead space or pockets under the skin that could form hematomas, seromas, and abscesses. o Obviously necrotic tissue (black, green, or gray) is removed first. In areas that have ample skin for closure, initial trimming of skin can be done more aggressively. In areas such as the distal limbs, trimming of skin should be done conservatively and questionable tissues given time to “declare” themselves. o Bone, tendons, nerves, and vessels are preserved as much as possible unless segments of these vital structures are completely separated from the tissue and obviously nonviable.

Answer 332

o Wounds that are heavily contaminated with road dirt or soil can be cleaned of debris using lukewarm tap water with a spray nozzle. o Maggots should be removed from severely necrotic wounds manually or with aggressive flushing. o Chlorhexidine and povidone-iodine can be used in dilute form (chlorhexidine 0.05% solution: 1 part chlorhexidine 2% to 40 parts sterile water; povidone-iodine 1% solution: 1 part povidone-iodine 10% to 9 parts sterile saline) as initial lavage in contaminated and infected wounds because of their wide spectrum of antimicrobial activity. o Povidone-iodine is more irritating to tissues, toxic to cells needed for wound healing, and inactivated by organic debris, so it may not be the preferred lavage solution. o Lactated Ringer’s solution or 0.9% saline are the most commonly used lavage solutions. An in vitro study demonstrated that normal saline and tap water cause mild and severe cytotoxic effects on fibroblasts, respectively, whereas lactated Ringer’s solution did not cause significant fibroblast injury.

Answer 333

o Lavage is performed by flushing with a bulb syringe or a 60mL syringe with an 18-gauge needle. o In order to facilitate refilling, the syringe and needle setup are connected to a three-way stopcock and an intravenous fluid bag.

Answer 334

o They are advantageous because they are readily available, are inexpensive, can be used both for debridement and to treat infections, and adhere to moist wound management principles. o Sugar has a bactericidal effect through its osmotic action, and it draws macrophages to the wound, which accelerates sloughing of devitalized tissue. o It is especially advantageous because it is effective and economical for large wounds.

Answer 335

Indications include degloving and shearing injuries, infected wounds (Streptococcus, Escherichia coli, and Pseudomonas spp), burns, and other wounds that require further debridement.

Answer 336

o The wound is first debrided and lavaged. o The area is then patted dry with a sterile towel before applying a coating (up to1 cm thick) of granulated sugar. o Sterile towels or lap sponges are used as the dressing in the primary layer, and then a thick, absorbent secondary layer is applied. o Bandages are changed at least daily, or more frequently if strikethrough occurs. o Sugar application is stopped when healthy granulation tissue appears

Answer 337

One disadvantage of sugar is that it may cause greater effusion in wounds, thus requiring more frequent bandage changes.

Answer 338

o Decreases edema, accelerates sloughing of necrotic tissue, and provides a rich cellular energy source, promoting a healthy granulation bed. o In addition, it has antibacterial properties because of its high osmolarity, acidity, and hydrogen peroxide content. o The hydrogen peroxide is present in levels that are harmless to healthy tissue. o Honey can be used during the debridement phase and also over infected granulation tissue. o It has been shown to be more effective in some cases than more expensive commercial products, including silver sulfadiazine and conventional dressings (i.e., impregnated gauze, polyurethane films).

Answer 339

o Honey is applied to the wound after hydrotherapy and debridement of necrotic tissue. o Gauze sponges soaked in honey are placed directly on the wound as the primary layer, then covered with an absorbent second layer to prevent it from leaking through the bandage. o As with sugar, dressings may need to be changed one to three times a day, and the wound should be lavaged and reassessed before each application of honey.

Answer 340

1. Primary 2. Secondary 3. Tertiary

Answer 341

The primary layer is the dressing applied directly to the wound. This layer determines the purpose of the bandage by whether it is an adherent or nonadherent dressing.

Answer 342

The secondary layer is com- posed of padded material that aids in absorption of exudates

Answer 343

Is the outermost protective layer that holds the others in place

Answer 344

o An adherent dressing is used when the wound is in the debridement phase, providing mechanical debridement. o The most common of these is the wet-to-dry dressing, in which sterile gauze sponges soaked with sterile lactated Ringer’s solution or 0.9% saline are wrung out and applied directly to the surface of the wound, then covered with dry, sterile gauze sponges. o The dry sponges soak up moisture from the wet ones, and this causes necrotic tissue and debris to adhere to the sponges when they are removed. o It is often necessary to wet the dressing slightly with sterile lactated Ringer’s solution or 0.9% saline to allow easier removal and to make it less uncomfortable for the patient. o During the debridement phase, it is necessary to change the wet- to-dry dressing and bandage at least once daily or more often, depending if moisture quickly “strikes through” to the outer layer of the bandage.

Answer 345

o Because they non-selectively remove both necrotic and healthy tissue alike. o Moist wound management principles are becoming increasingly popular in veterinary medicine because of improved wound understanding and technologic advances in wound products. o It has been demonstrated the benefit of a moist environment in optimizing wound healing by increasing epithelialization compared with leaving wounds open to air. o By providing a moist wound environment, the process of autolytic debridement can be more effective, which means that the body’s own phagocytic processes will take care of wound debridement.

Answer 346

o Alginates, foams, hydrogels, hydrocolloids, and transparent films are examples of some newer types of nonadherent dressings that can be selected based on their specific benefits to promote moist wound management through all phases of wound healing. o These products are more expensive than traditional gauze, but an overall cost savings can be realized because frequency of bandage changes decreases from several times a day to once every 1 to 3 days and improved wound healing leads to faster healing times. o The more commonly used nonadherent dressings such as Telfa pads are most appropriately used once a healthy, pink granulation bed has covered the surface of the wound and it is no longer infected.

Answer 347

o Alginates, foams, hydrogels, hydrocolloids, and transparent films are examples of some newer types of nonadherent dressings that can be selected based on their specific benefits to promote moist wound management through all phases of wound healing. o These products are more expensive than traditional gauze, but an overall cost savings can be realized because frequency of bandage changes decreases from several times a day to once every 1 to 3 days and improved wound healing leads to faster healing times. o The more commonly used nonadherent dressings such as Telfa pads are most appropriately used once a healthy, pink granulation bed has covered the surface of the wound and it is no longer infected.

Answer 348

o The secondary layer can be either a soft padded bandage or a tie-over bandage. o Soft padded bandages are used to protect soft tissue wounds on the limbs, and a splint can be incorporated between the second and third layers to stabilize distal fractures or ligamentous injuries. o The secondary layer is most commonly rolled cotton that is held in place with rolled gauze. The splint is placed over the cotton and under the gauze. o The tertiary layer is often Vetrap or Elastikon and is placed over the secondary layer but without compression of the bandage or wound.

Answer 349

o The tie-over bandage is used for wounds on areas of the body that are not amenable to soft padded bandages, such as the flank, perineum, or hip areas. o Materials include 2-0 to 0 nylon, umbilical tape, gauze, and water-impermeable drape material. o Loose suture loops are applied circumferentially around the wound. o The secondary layer consists of several layers of dry gauze squares or laparotomy sponges that are applied for padding and moisture absorption. o The tertiary layer is a water-impermeable drape cut to fit the wound, and then all three layers are held in place by the umbilical tape that is looped through the sutures in a shoelace fashion.

Answer 350

o Exposed bone is prone to slow healing and must be covered with a granulation bed before skin graft or flap application. o Seen most often with carpal or tarsal shearing injuries caused by motor vehicle trauma. In most cases exposed bone is eventually covered by advancing granulation tissue from surrounding healthy soft tissues. o Bone perforation can enhance wound healing by encouraging growth of granulation tissue over the exposed bone. Once the wound has entered the repair phase, a Jacob’s chuck and 0.045- to 0.062-inch K-wires may be used to perforate the surface of exposed bone through to the medullary cavity. Blood should not be wiped away. o A nonadherent dressing with antibiotic ointment should be applied as the primary layer of the bandage. o Bandage changes are done at 3- to 5-day intervals. Once a complete layer of granulation tissue is present (approximately 7 to 10 days), a free skin graft is applied or ongoing wound management continued until second- intention healing is complete. o Negative pressure wound therapy has also been shown to improve coverage of exposed bone in the case of distal extremity shearing wounds in dogs

Answer 351

1. Amount of time that has elapsed since injury. Wounds older than 6 to 8 hours are initially treated with bandages. 2. Degree of contamination. Obviously contaminated wounds should be thoroughly cleansed and initially treated with bandages. 3. Amount of tissue damage. Wounds with substantial tissue damage have reduced host defenses and are more likely to become infected; therefore they initially should be treated with bandages. 4. Completeness of debridement. Wounds should remain open if the initial debridement was conservative and if further debridement is necessary. 5. Status of the wound's blood supply. A wound with questionable blood supply should be observed until the extent of nonviable tissue is determined. 6. The animal's health. Animals unable to tolerate prolonged anesthesia are best treated with bandages until their health improves. 7. Extent of tension or dead space. If excessive tension or dead space is present, wounds should be bandaged to prevent dehiscence, fluid accumulation, infection, and delayed wound healing. 8. Location of the wound. Large wounds in some areas (e.g., limbs) are not amenable to closure.

Answer 352

o Clean, fresh wounds, small, contaminated wounds or even infected wounds that can be excised completely should be closed primarily. Monofilament absorbable suture should be used in subcutaneous tissue and muscle, and nonabsorbable suture should be used on the skin. Avoid tight sutures and tension on the suture line. o Closure should be delayed for contaminated wounds or large wounds with questionable viability. o Closure can be performed when a healthy granulation bed is present, which occurs during the repair phase of healing. Healthy granulation tissue should be pink, smooth, or slightly bumpy, should cover the entire wound, and should bleed on the cut surface or when an adhered dressing is removed. If in doubt, the wound should be treated as an open infected wound until the granulation bed is more definitively healthy.

Answer 353

o Delayed primary closure of a wound is performed 2 to 5 days after the injury. o Secondary closure of a wound is defined as closure of a wound 5 or more days after the inciting injury and is usually selected for wounds that were initially classified as dirty.

Answer 354

o Second-intention healing occurs over a healthy granulation bed by the processes of wound contraction and epithelialization, which continue until the two epithelialized edges of the wound meet. o Second-intention healing, even of very large wounds, can often be successful and does not require anything more than diligent bandaging and wound care. o Body wounds are more apt than leg wounds to completely close by secondary intention. o Disadvantages of healing by secondary intention include contracture with disfigurement, incomplete healing, and fragile epithelial scars with large wounds.

Answer 355

During wound closure in areas with excessive dead space, areas with potential for fluid accumulation, or infected or contaminated areas (e.g., abscess, bite wound).

Answer 356

o The drain should exit from the dependent portion of the wound via a separate stab incision, not through the suture line. o Ideally the drain should be covered with a bandage to prevent removal by the patient, to further compress dead space, and to keep the area clean. o Drains are removed when drainage is clear or minimal (2 to 7 days)

Answer 357

Active and passive

Answer 358

o A Penrose drain is the best means of passive gravitational drainage. o This type of drain can be secured at the proximal extent of the wound pocket with a simple interrupted suture through the skin that catches the flimsy rubber tubing while it is held in position with a hemostat. o A separate opening to secure a Penrose drain proximally should never be made because this allows bacteria to migrate into the wound. o The Penrose drain should exit the wound pocket at its most dependent location and be secured with a simple interrupted or cruciate suture to the skin edge of the opening where it exits the wound pocket.

Answer 359

o There are many types of active or closed-suction drains, which consist of a vacuum-generating reservoir connected to fenestrated tubing. o These can be used only in areas that can be closed completely because a vacuum must be created within the wound. o There are numerous commercially available closed-suction drains such as the J-VAC and the Sil-Med vacuum drain, which has a grenade-type reservoir. o There are also several ways to make closed suction devices. A butterfly catheter and red-top blood collection tube can be used for small spaces. o For larger areas of dead space, a drain can be made of intravenous tubing with additional fenestrations cut out of the segment to be placed in the wound using a number 15 scalpel blade. The tubing is then connected to a 60-ml syringe, and the plunger is held open with a needle or pin.

Answer 360

o Topical negative pressure (TNP) and negative pressure wound therapy (NPWT) are the generic terms used to describe the application of a vacuum to a wound to promote and hasten healing by second intention and to prepare wounds for closure with skin flaps or grafts. o Vacuum-assisted closure (VAC) refers to a commercially available device.

Answer 361

o The basic materials needed include open-pore polyurethane foam or open-weave gauze sponges for the contact layer, suction tubing, adhesive occlusive film, and a suction device with a canister to hold the evacuated fluid. o The contact layer is fitted to the contours of the wound and then sealed with the adhesive occlusive film that overlaps the wound edges by at least 5 cm21 and that must form a leakproof seal to maintain the vacuum. o A drainage tube is connected to the foam dressing through an opening in the adhesive film. The drainage tube is then connected to a vacuum source most commonly set at −125mmHg.

Answer 362

o Increased vascularization, improved granulation tissue formation, and a reduction in the wound volume/size. o Clinical advantages of NPWT include more optimal fixation of skin grafts, better management of highly exudative wounds, and decreased costs because of the need for less frequent bandage changes

Answer 363

o Prolonged use leads to decreased wound contraction (at >7 days), higher bacterial load (at day 7), and decreased percent epithelialization (at >11 days) compared with a standard absorbent foam wound dressing.

Answer 364

o Necrotic tissue with eschar present o Untreated osteomyelitis o Nonenteric and unexplored fistulas o Malignancy in the wound o Exposed vasculature, nerves, anastomotic site or organs. o Patients with active bleeding, bleeding disorders or on anticoagulant therapy.

Answer 365

o It has been described VAC use in distal limb injuries, to decrease the size of large wounds and bolster bandaging of skin grafts, in cases of surgical dehiscence/ infection over orthopedic implants, in degloving wounds, in chronic nonhealing wounds, and for postoperative edema and seroma prevention. o Other uses include in cases of peritonitis, for open management of bite wounds over the thorax, and in compartment syndrome.

Answer 366

o Hyperbaric oxygen therapy involves placing patients in a chamber that replaces room air with 100% oxygen under pressure. o This creates a gradient that increases the partial pressure of oxygen dissolved in the plasma (PaO2) and that subsequently diffuses across capillary membranes, into the interstitial space and ultimately into peripheral tissues. o Hyperbaric oxygen therapy has not been well studied in dogs and cats but may promote angiogenesis (which is fostered by the increased oxygen gradient), increased proliferation of fibroblasts, and increased leukocyte oxidative killing of bacteria. o In addition, decreased edema after hyperbaric therapy allows better diffusion of oxygen and nutrients to the affected tissues while relieving pressure on surrounding vessels and structures. o Animals that are most likely to benefit include those with crush injuries, compromised skin grafts, severe burns, and infections with anaerobic organisms.

Answer 367

o Low level laser-light therapy (LLLT), or “cold” laser, is better described by the name photobiomodulation. o This technology uses low levels of red and near-infrared light to penetrate tissue and increase ATP production in the mitochondria of chromophores, as well as promote healing via the activation of fibroblasts. o LLLT is used routinely in human medicine, and more recently in veterinary medicine, to reduce inflammation and promote healing of wounds and deeper tissues. o Although there appears to be clinical evidence supporting the use of LLLT, good randomized controlled trials are lacking and results are often not repeatable because of differences in laser technology.

Answer 368

o Shockwave therapy is a treatment modality that generates acoustic waves that travel through tissue to induce perturbations at the cellular level, which reportedly upregulates immunomodulatory mechanisms. o There is limited evidence in both experimental and clinical studies that shockwave therapy may promote wound healing.

Answer 369

o The most common bacterial wound pathogens include G+ Staphylococcus spp and Streptococcus spp and G- such as Escherichia coli, Enterococcus, Proteus spp, and Pseudo- monas spp. o When humans (or animals) are bitten by dogs and cats, Pasteurella multocida is a common oral pathogen. o The most common anaerobic isolates in bite wounds include Bacillus spp, Clostridium spp, and Corynebacterium spp. o Often Pseudomonas will be an acquired infection on the surface of the granulation bed, noticeable by the wound’s slimy feel and obvious pungent odor. Rarely does this organism cause systemic infection and thus it does not necessitate systemic antimicrobial therapy.

Answer 370

o Systemic antimicrobials are indicated for contaminated and infected wounds to help eliminate bacteria and promote healing. o Some clean, recent wounds, such as sharp lacerations, do not require microbial evaluation, and superficial wounds that are easily debrided and closed may require only perioperative antimicrobial use.

Answer 371

o A Gram stain can be performed to determine the predominant bacterial population and guide the initial antimicrobial selection. o C&S testing of the wound should be done AFTER initial debridement and lavage.

Answer 372

o Superficial wounds in systemically stable animals are best treated with a bactericidal antimicrobial that is effective against G+ bacteria, such as cefazolin or cephalexin, pending culture and susceptibility results. o Infected, deeper wounds may require a broader-spectrum antimicrobial such as amoxicillin with a β-lactamase inhibitor such as clavulanic acid. o In one study the most commonly cultured bacteria from bite wounds (Staphylococcus, E. coli, Enterococcus spp) were 100% sensitive to amoxicillin and clavulanic acid.

Answer 373

Debridement and lavage

Answer 374

Is more effective for preventing infection than treating it, and it has poor activity against Pseudomonas.

Answer 375

Has a favorable broad-spectrum coverage and is the agent of choice for burn wounds.

Answer 376

Is a broad-spectrum antimicrobial agent with hydrophilic properties; it dilutes thick exudates for better absorption into bandages.

Answer 377

Are effective treatment of wounds infected with Pseudomonas and are often used on open wounds before skin grafting is done

Answer 378

o Anemia, severe trauma, or hypovolemia can delay wound healing because of poor oxygen delivery to the wound. o Poor perfusion and nutritional status can also have detrimental effects on healing. o Serum total protein levels less than 2 g/ dl impede wound repair by decreasing fibrous tissue deposition. o Infection and foreign bodies cause intense inflammatory reactions that interfere with healing. o Patients with cancer that are receiving chemotherapy or those who have had radiation therapy to the area of the wound will also be prone to delayed wound healing. o Patients with diabetes, uremia, liver disease, or hyperadrenocorticism are susceptible to infection or delayed healing as well. o Corticosteroids decrease the inflammatory phase of healing and the rate of protein synthesis; however, vitamin A (10,000 IU/dog PO q24h) can antagonize these detrimental effects of corticosteroids.

Answer 379

o Sutured wounds in cats are only half as strong as those in dogs by day 7. o Cats demonstrate significantly less granulation tissue production than dogs in wounds that were evaluated for second- intention healing.

Answer 380

Extension and location of the wound.

Answer 381

The degree of the injury and the percentage of body surface area involved.

Answer 382

Electric heating pads, fire exposure, scalding water, stovetops, radiators, heat lamps, automobile mufflers, improperly grounded electrocautery units, and radiation therapy.

Answer 383

Epidermis Dermis The dermis is composed of a superficial plexus and a middle plexus, where hair and glandular structures arise.

Answer 384

o Below the dermis lies the hypodermis, which contains the deep or subdermal plexus and the panniculus muscle. o The subdermal plexus brings the blood supply to overlying skin through the superficial and middle plexus of the dermis. o Capillary loops in the superficial plexus supply the epidermis.

Answer 385

Because the capillary loops in the superficial plexus of the dermis are poorly developed in the dog and cat compared with humans, leading to less severe erythema and blisters than human burn victims.

Answer 386

o First-degree burn wounds are superficial and are confined to the outermost layer of the epidermis. o The skin will be reddened, dry, and painful to touch.

Answer 387

o Second-degree burn wounds are partial-thickness injuries that involve the epidermis and a variable amount of the dermis. o If only the superficial part of the dermis is affected, there will be thrombosis of blood vessels and leakage of plasma. The hair follicles are spared. o In deeper partial-thickness burns, hair follicles are usually destroyed, the skin appears yellow-white or brown, and there is decreased sensation except to deep pressure.

Answer 388

o Third-degree burn wounds are full-thickness injuries that have destroyed the epidermis and entire dermis. The skin is leathery and charred and lacks sensation. o Fourth-degree burn wounds have the same characteristics as third-degree burn wounds but also affect deeper tissues such as muscle, tendon, and bone

Answer 389

o Up to 3 days. o Because burned skin retains heat - during that time thermal injury and circulatory compromise from thrombosed vessels can continue.

Answer 390

o Eschar is a deep cutaneous slough of tissue composed of full- thickness degenerated skin. o When skin is severely burned, it forms an eschar within 7 to 10 days. o It appears as a black, firm, thick movable crust that separates from the surrounding skin. o Purulent exudates often lie beneath the eschar, particularly if it covers deep or extensive injuries, and sepsis can result if not treated promptly.

Answer 391

o When they have more than 20% of TBSA burned or if the burns are classified as second and third degree. o As a result of capillary thrombosis and plasma leakage, massive amounts of fluid are retained in the wound, often leading to burn wound edema. o This results in the loss of fluid and electrolytes, with the most dramatic losses occurring within the first 12 hours.

Answer 392

Hemoconcentration will be noted initially because of the dramatic loss of plasma; however, red blood cell hemolysis also occurs from both direct damage and destruction through the damaged microcirculation.

Answer 393

o The patient should be monitored for disseminated intravascular coagulation (DIC), upper airway edema, and oliguria. o Between days 2 and 6, the patient should be assessed for anemia, DIC, immune dysfunction, SIRS, and early burn wound infection. o From day 7 and on, the clinician should watch for hyperthermia, hypoxemia, pneumonia, sepsis, and wound demarcation.

Answer 394

o Total fluid delivery rate during the first 24 hours should be 1 to 4 ml/kg body weight × % TBSA burned.

Answer 395

0.5 ml/kg body weight × % TBSA burned

Answer 396

By 48 hours after injury, plasma volume is mostly restored, and thus patients are at high risk for generalized edema and fluid overload from the high initial demands for fluid replacement.

Answer 397

FALSE o Because of their fragile metabolic state, the importance of adequate nutrition cannot be overemphasized in patients with healing burn wounds. o Nutritional requirements should be based on the patient’s needs; an initial estimate is made by calculating the resting energy requirement. o The diet should be high calorie and high protein, and the quantity of food can be increased as tolerated by the patient. o It is best if the patient can eat voluntarily, but if the animal is not consuming adequate nutrition, an esophagostomy tube should be placed or total parenteral nutrition commenced. o GI protectants are recommended to manage GI ulceration secondary to GI hypoperfusion.

Answer 398

o Although severely damaged skin is often numb, deeper viable tissues and surrounding areas are often hypersensitive and thermal damage may be ongoing; thus one should assume that burn patients experience extreme pain. o Good systemic analgesics include methadone, hydromorphone or fentanyl as a CRI. o A fentanyl patch may not be appropriate in animals with more than 20% TBSA burned or who are still being treated for hypovolemic shock because of altered absorption. o Good nursing care is important, and animals should be turned every 4 hours if recumbent to prevent decubitus ulcers. o PROM limb exercises can help prevent edema and maintain mobility.

Answer 399

o Sepsis is one of the greatest threats to burn patients with extensive TBSA involvement, because bacteria can colonize and proliferate in wounds that have lost the protective skin barrier. o The best way to prevent local and systemic infection is to protect the wound from contamination in the hospital environment, and to remove all necrotic tissue and purulent exudates from the wound surface as aggressively as possible through serial debridement. o Systemic antimicrobials are not indicated unless the patient is immunocompromised, has pneumonia or pulmonary injury, or sepsis is suspected. o Topical antibiotics are the antimicrobial treatment of choice. Because most invasive burn wound infections are caused by Pseudomonas or other G-, antimicrobials against these bacteria are administered empirically until C&S testing results are available

Answer 400

o If the patient presents within 2 hours of the burn injury, cold water lavage for 30 minutes will often help to release heat from the skin and limit the depth of injury. o The temperature of the water should not be below 3° C, and if large body surface areas require treatment, it is important to prevent iatrogenic hypothermia. o The affected area can be submerged in a cold water bath if it is on a limb, and cool towels or cool water from a spray nozzle can be applied to other areas.

Answer 401

o In patients with superficial burns or superficial partial-thickness burns, it may be appropriate to use daily lavage and topical agents alone until the extent and depth of the wound is determined. o Deep partial-thickness and full-thickness burns require debridement, which can be done in three ways: conservatively, enzymatically, or surgically. o Conservative debridement is often used for the first 3 to 7 days as the wound declares itself and the patient stabilizes; then more aggressive surgical debridement can be performed.

Answer 402

o Involves hydrotherapy, removal of necrotic tissue, topical therapy, and bandaging. It may need to be done more than once a day initially for wounds that are necrotic or exudative. o Hydrotherapy -> gentle lavage of the wound with room temperature sterile saline or LRS. This helps to loosen and separate any nonviable or necrotic tissue from the surface of the burn. o The lavage solutions should be delivered using a 35mL syringe and a 19-gauge needle to create a pressure of 8psi. o Higher pressures may induce tissue trauma and cause deeper seeding of bacteria into the burn. o A wet-to-wet dressing under a bandage can also be placed on burns for several hours at a time to slowly loosen the necrotic tissue and facilitate debridement. o Conservative debridement is characterized by the daily serial removal of necrotic tissue using aseptic technique, with either sterile gauze or sterile scissors and thumb forceps. o Because necrotic tissue is without sensation, this may not require daily general anesthesia; however, manipulation of deeper viable tissues and surrounding hyperemic areas likely will be painful during lavage. o This form of debridement is acceptable initially, when there is no clear definition of nonviable tissue, or when it is prudent to be conservative in areas overlying tendons, ligaments, and bone.

Answer 403

o Is the use of topical agents to soften, loosen, and digest necrotic tissue, facilitating removal with gentle lavage. o The advantages are that it does not require general anesthesia and also spares healthy tissue. o Because some of the commercially available agents are expensive, it is most cost effective to use them on small limb wounds. o The most commonly used enzymatic topical agent contains trypsin, balsam Peru, and castor oil. This product should be applied only in the early stages of wound therapy, then discontinued once a healthy bed of granulation tissue has been established.

Answer 404

o It is indicated in deep partial-thickness and full-thickness burn wounds that may otherwise take days or weeks with conservative debridement. o This is done most easily on large areas of the trunk or small areas of the limbs, which can then be closed primarily. o If the area cannot be closed primarily, it will take about 5 to 7 days for a healthy granulation bed to form, at which time flap or skin graft surgery can be performed.

Answer 405

Aloe vera and silver sulfadiazine

Answer 406

o Aloe vera cream has antithromboxane effects that prevent vasoconstriction and thromboembolic seeding of the dermal vasculature. o Ideally, using it within the first 24 hours can help prevent progression of superficial partial-thickness burns. o Aloe vera is applied liberally to the surface of the wound with a sterile gloved finger while the patient is sedated, because these wounds are painful when touched. o The wound should then be covered with a nonadherent hydrophilic dressing and bandage.

Answer 407

o After the first 24 hours, SSD should be applied. o It has a wide spectrum of bactericidal activity against G+ and G- bacteria and Candida. o The cream is placed directly on the wound under the contact layer of a bandage using sterile gloves. o For very large areas that are not amenable to bandaging, SSD should be slathered over the wound and the patient confined within a low-fomite environment (empty clean cage with no blankets or stuffed toys). o If needed, the cream can be rinsed off gently before reapplication, up to 2 to 3 times a day. o SSD can be used during both the early debridement stage under wet-to-wet dressings and through the repair stages of healing using nonadherent bandages. o Alternatively, nanocrystalline silver dressings that allow for slow sustained release of silver are a slightly more expensive option that can be left on the wound for up to 3 to 7 days. o Medicinal honey and sugar can also be used in the treatment of burn wounds; they are beneficial during debridement and help to control secondary infections

Answer 408

o Scarring and wound contracture are the biggest complications in patients with burn wounds left to heal by second intention. o This is particularly a concern for patients with burn wounds in the axillary or inguinal areas, or around joints, which can lead to decreased mobility and range of motion of the limbs. o Wounds in these areas should be managed by someone experienced in reconstructive surgery because they will likely require skin grafts or flaps.

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