U1 O2 - Shock, vascular access and fluid therapy Flashcards

Question

What can be assessed to assess the results of a resuscitation ?

Answer 1

Arterial blood pressure Central venous pressure Mixed/central venous oxygen levels Quantification of urine output Lactate measurements

Answer 2

8mmHg (10.5 cmH2O)

Answer 3

24 hours dogs and cats Labs such as PCV/TP and urine SG can help to assess

Answer 4

Tacky mms History fluid loss/no drinking

Answer 5

Slow return of skin tent Dry mms

Answer 6

Slow return of mms Dry mms Sunken eyes

Answer 7

Slow return of skin tent or stays tented Sunken eyes (protruding third eyelid for cat) Dry mms Decreased mentation/ unresponsive Dull desiccating corneas Cold extremities

Answer 8

Deficit (ml) = BW (KG) x 10 x % dehydrated

Answer 9

40-60ml/kg/day Or Same as RER 30x BW +70

Answer 10

0.5 mmol/kg/hour As cardiac arrhythmias may occur

Answer 11

The process of producing cellular energy involving oxygen

Answer 12

The process of producing cell energy when there is not enough oxygen for aerobic respiration. Glucose → lactic acid (+ energy released)

Answer 13

A pH imbalance where too much acid has accumulated in the body or too much alkali (bicarbonate) has been lost from the body.

Answer 14

The result of hypoventilation and accumulation of CO2.

Answer 15

The volume of blood pumped out of the left ventricle with | every heart beat.

Answer 16

The force exerted on the walls of arteries as blood is pumped from the left ventricle.

Answer 17

Situation where oxygen delivery to cells/ tissues is insufficient for demand inadequate cellular energy production or decreased cellular oxygen utilization related to decreased blood flow that leads to cell death and organ failure Whilst, there are many definitions for shock it is considered to be failure of the circulatory system to adequately perfuse vital organs. This means the basic metabolic requirements for cells are not delivered which can quickly lead to cell death

Answer 18

Systemic Inflammatory Response Syndrome SIRS represents the body’s excessive response to an inciting event/insult e.g. tissue damage (septic or non-septic), in certain circumstances. Normally, following an inciting event/insult e.g. injury/infection which causes tissue damage, there is a localised proinflammatory response, associated with the release of pro-inflammatory mediators and acute phase proteins (Lewis, 2014). In an individual patient, if the inciting event/insult is severe enough, a systemic pro-inflammatory response develops i.e. the localized inflammatory response becomes systemic (generalised). N.B. remember that inflammation is the response if living tissue to injury- the normal inflammatory response is the body’s first line of defense following injury. It is usually a localised, acute response intended to be short-lived and to only work on damaged cells and tissues.

Answer 19

The presence of viable bacteria in the blood

Answer 20

Clinical manifestations of SIRS secondary to an infectious | cause

Answer 21

Sepsis with evidence of dysfunction of at least one organ

Answer 22

Severe sepsis associated with hypotension; that is unresponsive to appropriate fluid resuscitation Septic shock- is defined as sepsis with refractory hypotension that does not respond to normal interventions or fluid therapy.

Answer 23

Dysfunction of the endothelial, cardiopulmonary, renal, nervous, endocrine and gastrointestinal systems associated with the progression of systemic inflammation

Answer 24

Disseminated Intravascular Coagulation

Answer 25

Solutions of electrolytes and / or glucose in water

Answer 26

Colloids are macromolecules in solution: they are retained | intravascularly and exert colloid osmotic pressure

Answer 27

Most cases of shock are caused by decreased blood supply to tissues meaning decreased delivery of oxygen to tissues.

Answer 28

Oxygen is essential for normal cell energy production and function (Thomovsky and Johnson, 2013). Shock is a syndrome resulting from inadequate cellular energy production. This arises due to an imbalance between oxygen delivery (DO2) and oxygen consumption (VO2)

Answer 29

As well as having a reduced DO2, many patients in shock, have an increased metabolic requirement for oxygen which worsens the imbalance. In the absence of oxygen, cell respiration changes from aerobic, which is efficient, to anaerobic cellular metabolism which is inefficient.

Answer 30

Anaerobic metabolism provides a temporary fix for the inadequate cellular energy production but results in lactic acid/ lactate accumulation and metabolic acidosis.

Answer 31

Because anaerobic metabolism is less efficient than aerobic, insufficient energy is produced to allow the cells to perform their normal functions leading to abnormal cell function and cell death.

Answer 32

ongoing anaerobic respiration results in harmful substances being produced (e.g. cytokines, lactate and nitric oxide) which also causes cell damage and cell death (Thomovsky and Johnson, 2013).

Answer 33

There are four main categories of shock recognised in small animals. 1) Hypovolaemic 2) Cardiogenic 3) Distributive 4) Obstructive

Answer 34

``` Shock most commonly results from alterations in tissue perfusion- this could be due to loss of intravascular volume which leads to decreased venous cardiac return/ cardiac preload (very common) (hypovolaemic shock); ```

Answer 35

cardiac dysfunction (cardiogenic shock)

Answer 36

maldistribution of blood flow | distributive or septic shock

Answer 37

obstruction | to normal blood flow (obstructive shock)

Answer 38

All the types of shock cause similar clinical signs which are associated with reduction in cardiac output and poor perfusion; the treatment, however, differs for cardiogenic shock which is normally an issue with maintaining systolic function rather than a loss of circulating volume.

Answer 39

Hypovolaemic shock and septic shock are the two most common causes of shock in veterinary practice

Answer 40

Common causes of hypovolaemic shock include o Haemorrhage (trauma, surgical, coagulopathy etc.) o Gastrointestinal losses (e.g. vomiting secondary to gastrointestinal foreign body).

Answer 41

Common causes of septic shock include septic peritonitis, pyometra and pyothorax.

Answer 42

Causes of obstructive shock include pericardial effusion, gastric dilation and volvulus and pulmonary thromboembolism (some sources consider obstructive shock to be a type of hypovolaemic shock). Any type of condition that leads to an obstruction of blood flow to, through or out of the heart could be considered an obstructive syndrome in that the obstruction needs to be alleviated to restore normal perfusion. Other causes of obstructive shock can include gastric dilation and volvulus, pulmonary thromboembolism and heartworm disease

Answer 43

End-stage dilated cardiomyopathy and severe arrhythmias are examples of cardiogenic shock.

Answer 44

``` Oxygen delivery (DO2) is dependent on cardiac output and local tissue blood flow (perfusion) ```

Answer 45

Cardiac output= stroke volume x heart rate.

Answer 46

Blood pressure is affected by - • Cardiac output • Total peripheral resistance -the resistance the blood encounters as it travels in the blood vessels (vasodilation- low resistance; vasoconstriction/ arterial occlusion- high resistance) • (Blood viscosity)

Answer 47

decreased cardiac output could lead to decreased blood pressure (hypotension). Hypotension will lead to decreased tissue perfusion.

Answer 48

Consider again, the garden hose trying to unsuccessfully water the flowers. One way of increasing the amount of water going to the flowers is to increase the output from the hose i.e. turn the tap on more (equivalent to ↑ cardiac output); another option is to pinch the hose to make the stream of water narrower (↑ blood vessel tone/ peripheral vasoconstriction) so that, temporarily, only the flowers in the centre (the most important ones) are watered effectively; the less important flowers on the periphery are temporarily deprived of a water supply until the problem can be fixed….. ➢ What happens to the flowers on the periphery if they remain deprived of water? ➢ What will ultimately happen to the water supply to all the flowers if the water supply cannot be restored? ➢ Now consider what happens in a patient that has lost/ is losing blood volume….

Answer 49

Hypovolaemic shock Hypovolaemic shock arises from depleted, effective intravascular volume. The hypovolaemia leads to decreased venous return/cardiac preload (end-diastolic volume) and a subsequent reduction in stroke volume as demonstrated below -

Answer 50

1. Internal or external blood loss (haemorrhagic shock) 2. Excessive loss of other body fluids (through vomiting, diarrhoea, burns, polyuria) resulting in progressive dehydration and eventual loss of intravascular volume N.B. It is important to appreciate that dehydration and hypovolaemia are NOT the same however 3. Obstruction to venous return, as in gastric dilatation and volvulus (obstructive shock.

Answer 51

Following any drop in cardiac output and decreased cell oxygenation, compensatory mechanisms are activated aimed at maintaining normal blood pressure and thus tissue perfusion, with delivery of oxygen. These compensatory mechanisms aim to increase cardiac output and blood vessel tone and so increase cell perfusion.

Answer 52

These compensatory mechanisms are both neural and hormonal – neuroendocrine responses; and are mediated by the hypothalamo- pituitary- adrenal (HPA) axis - the sympatho-adrenal response.

Answer 53

Compensatory Mechanisms Based on how rapidly they are activated and start to have an effect, the compensatory mechanisms are considered– • Acute (immediate onset; response within minutes) • Moderate (response within 10- 60 minutes) • Chronic (response within 1-48 hours)

Answer 54

Acute (immediate onset; response within minutes)

Answer 55

Moderate (response within 10- 60 minutes)

Answer 56

Chronic (response within 1-48 hours)

Answer 57

Acute- these are focused on increasing venous return to the heart and increasing the blood supply to the myocardium to enable it to function effectively under increased demands. They are temporary steps triggered by the sympathetic nervous system to keep the animal alive. However, if treatment is not instigated rapidly these compensatory measures are likely to fail, leading to decompensated shock.

Answer 58

Decreasing blood volume leads to decreased baroreceptor impulses (less pressure if less blood in blood vessels). This stimulates the sympathetic nervous system leading to increased sympathetic activity and catecholamine release (nor-adrenaline/ norepinephrine)- resulting in peripheral vasoconstriction, tachycardia and an increase in cardiac contractility

Answer 59

Nor-adrenaline/ nor-epinephrine binds to α receptors on blood vessels to cause vasoconstriction and β-1 receptors in the heart to cause increased heart rate and force of contraction. Peripheral vasoconstriction diverts blood to essential organs and the positive inotropic and chronotropic effects increase cardiac output

Answer 60

Hypoxaemia, which is detected by chemoreceptors in the aorta and carotid artery, also results in increased sympathetic nervous system activity and catecholamine release

Answer 61

Cortisol release from the adrenal cortex is also an acute response to hypovolaemia. Whilst it is not clear what all the roles of cortisol are in a hypovolaemic patient, one main function is to provide an immediate glucose energy source. Cortisol plays a vital role in the normal maintenance of vascular tone and endothelial integrity; and regulation of fluid within extravascular compartments. It also potentiates the impact of catecholamines on vasoconstriction

Answer 62

Neurohormonal mechanisms are also activated aiming to return vascular volume to normal e.g. activation of the renin angiotensin aldosterone system (RAAS).

Answer 63

renin angiotensin aldosterone system (RAAS).

Answer 64

Decreased renal perfusion results stimulates baroreceptors in the kidney. This stimulates RENIN release which converts ANGIOTENSINOGEN to Angiotensin I then Angiotensin II Immediate response of Angiotensin II - peripheral vasoconstriction ( and reabsorbs some salt and water) Delayed response Angiotensin II - ALDOSTERONE release from adrenal cortex. Increased sodium, chloride and water reabsorption from distal convoluted tubules in kidney → increased blood volume

Answer 65

Decreased renal perfusion results stimulates baroreceptors in the kidney. This stimulates RENIN release which converts ANGIOTENSINOGEN to Angiotensin I then Angiotensin II

Answer 66

Immediate response of Angiotensin II - peripheral vasoconstriction ( and reabsorbs some salt and water)

Answer 67

Delayed response Angiotensin II - ALDOSTERONE release from adrenal cortex. Increased sodium, chloride and water reabsorption from distal convoluted tubules in kidney → increased blood volume

Answer 68

The net result of these neurohormonal responses is to retain more fluid at the kidney aiming to restore normal intravascular volume and increase cardiac preload/ venous return.

Answer 69

Whilst the short-term compensatory response of vasoconstriction can be lifesaving, it is not sustainable. If it continues for any length of time, cellular hypoxia and death will occur due to decreased perfusion.

Answer 70

The gastrointestinal tract (GIT) is especially of concern in cases of reduced perfusion. Whilst it is a large system within the body, during times of poor perfusion and “shock” blood flow to the GIT is reduced by up to 70%, as it is not essential to keeping the animal alive.

Answer 71

Whilst it is a large system within the body, during times of poor perfusion and “shock” blood flow to the GIT is reduced by up to 70%, as it is not essential to keeping the animal alive.

Answer 72

The gastrointestinal tract (GIT) is especially of concern in cases of reduced perfusion. Whilst it is a large system within the body, during times of poor perfusion and “shock” blood flow to the GIT is reduced by up to 70%, as it is not essential to keeping the animal alive. This decreased perfusion commonly leads to gastrointestinal complications, such as vomiting and diarrhoea, which can worsen hypovolaemia

Answer 73

Vasopressin/ antidiuretic hormone (ADH) is released from the posterior pituitary gland when the osmolarity of blood increases and the volume of blood decreases. An immediate effect of vasopressin, when there is hypovolaemia, is to bind to V1 receptors on peripheral arterioles (N.B. NOT α receptors) causing peripheral vasoconstriction (as angiotensin II and catecholamines also do).

Answer 74

Chronic These are responses to hypovolaemia, after the immediate, acute life-saving responses, that take slightly longer to have an effect and are aimed at increasing/ restoring blood volume. Aldosterone and ADH/ vasopressin act on nephrons to reabsorb sodium, chloride and water (aldosterone) and water (ADH). ADH binds to V2 receptors in the distal convoluted tubules to reabsorb water. The net effect of this is to restore blood volume (if no ongoing loss). ➢ Consider what effect these compensatory mechanisms will have on urine output

Answer 75

Aldosterone and ADH/ vasopressin act on nephrons to reabsorb sodium, chloride and water (aldosterone) and water (ADH). ADH binds to V2 receptors in the distal convoluted tubules to reabsorb water. The net effect of this is to restore blood volume (if no ongoing loss).

Answer 76

Cardiogenic Shock This, as its name suggests, is when the heart suffers major failure of forward flow such that the cardiac output is insufficient to allow perfusion of the whole body. This is not common but can occur due to severe, dilated cardiomyopathy, for example in dogs, where the thin myocardial walls are unable to develop sufficient contractile strength to produce an adequate stroke volume.

Answer 77

In feline patients, cardiogenic shock is more | commonly associated with hypertrophic cardiomyopathy and aortic thromboembolism.

Answer 78

Distributive / Septic Shock With distributive shock, there is abnormal distribution of blood caused by peripheral vasodilation

Answer 79

With distributive shock, there is abnormal distribution of blood caused by peripheral vasodilation. This causes in blood to pool in peripheral blood vessels and capillaries meaning there is decreased volume of circulating blood. This results in inadequate supply of blood to the body's tissues and organs.

Answer 80

With distributive shock, there is abnormal distribution of blood caused by peripheral vasodilation. This causes in blood to pool in peripheral blood vessels and capillaries meaning there is decreased volume of circulating blood. There is a different underlying cause and slight variation in clinical signs, initially, but the effect in the patient is like hypovolaemic shock e.g. there is less blood circulating than is required. It can be difficult to immediately identify hypovolaemic shock versus distributive shock based on clinical signs – it is very important is to monitor the patient’s response to treatment.

Answer 81

Patient’s with hypovolaemic shock will usually respond to (improve) bolus IVFT where patient’s with distributive shock often do not. This causes in blood to pool in peripheral blood vessels and capillaries meaning there is decreased volume of circulating blood. When a patient has septic shock, it remains hypotensive despite adequate fluid resuscitation and administration of sympathomimetics (which would normally cause peripheral vasoconstriction).

Answer 82

The underlying abnormality with distributive shock is vasoplegia- which literally means paralysis of blood vessels. The peripheral blood vessels cannot vasoconstrict which causes low systemic vascular resistance and pooling of blood. With this condition, there is hypotension despite normal or raised cardiac output.

Answer 83

``` Inflammatory mediators (produced in response to a serious cause e.g. major burns, septic focus) cause widespread vasodilation and vasoplegia of blood vessels. This means there is low vascular resistance due to failure of peripheral vasoconstriction ```

Answer 84

Systemic inflammatory response syndrome (SIRS) – is vasodilation and poor perfusion, without infection. It is possible for SIRS to occur on its own in cases such as pancreatitis. Sepsis – is defined as SIRS with an identifiable infectious cause

Answer 85

Septic causes are frequently obvious and are associated with bacterial, fungal, viral and parasitic causes Bacteria are perhaps the most common culprits, with the E. coli families that release endotoxins, highly represented. Examples include pyothorax, septic peritonitis and parvoviral enteritis.

Answer 86

Distributive shock may also be caused by anaphylaxis. Anaphylactic causes are associated with an inappropriate immune system response to an otherwise innocuous substance. If a previously healthy patient presents with acute, sudden onset collapse, the cause could be anaphylaxis

Answer 87

The presence of oedema in the wall of the gall bladder of the dog (halo sign), on ultrasound examination, is highly suggestive of anaphylaxis (Lisciandro, 2015). However, whilst this is helpful in trying to establish a diagnosis, there are other reasons for oedema of the gall bladder being present. Rarely, distributive shock can have a neurogenic cause.

Answer 88

With SIRS and sepsis, inflammatory chemicals are released into the blood stream which cause vasodilation, decreased perfusion of organs and hypotension leading to shock.

Answer 89

Early clinical signs include pyrexia, brick-red red mucous membranes, bounding pulses and rapid CRT < 1 second. Due to the vasoplegia, peripheral vasodilation and an initial hyperdynamic response (in dogs) (Koenig, 2011), the early signs of distributive shock differ from hypovolaemic shock

Answer 90

A cat with sepsis is not likely to have a hyperdynamic response marked lethargy, pale mucous membranes, tachypnoea, weak pulses, hypotension, hypothermia, icterus, and diffuse abdominal pain (Koenig, 2011). Cats may progress through compensated responses without the owner noticing that too much is wrong and so they often present when decompensated. Depending on how advanced the condition is there may be tachycardia or bradycardia- bradycardia is a very serious sign as it indicates severe sepsis /worsening of the condition.

Answer 91

Obstructive shock is not included in all classifications of shock- some consider it to be a type of hypovolaemic shock but with a different aetiology. An example is a pericardial effusion. Due to fluid within the pericardial sac, insufficient blood can return to the right atrium (pre-load) resulting in reduced cardiac output- this is called ‘tamponade’. In this situation, there is not actually decreased blood volume but there is decreased venous return due to obstruction. Removing this obstruction (e.g. by performing pericardiocentesis) will cause resolution of the clinical signs of shock. Pericardial effusions will sometimes be classified under cardiogenic shock.

Answer 92

There are certain groups of veterinary patients at risk of developing shock syndromes even if they do not present for those. For example, patients that have ongoing inflammation or infectious processes can develop SIRS +/- sepsis during the hospitalisation period for the initial complaint. A patient with pancreatitis often has ongoing inflammation for several days and may develop SIRS as a result of this. A patient with parvovirus may develop sepsis on day two/ three as the body is overwhelmed by inflammatory mediators

Answer 93

• Compensated shock- this is the early phase of shock where the body's compensatory mechanisms can maintain adequate perfusion of the brain and vital organs. The patient is likely to have a normal blood pressure at this stage as cardiac output is being maintained.

Answer 94

Decompensated shock- this is when the compensatory mechanisms are not able to fix the underlying problem. With ongoing lack of perfusion and increasing cell death, progressive peripheral vasodilation starts to occur with pooling of blood. This means the circulation is even less effective and less blood is delivered to vital organs. The patient becomes increasingly stuporous or comatose; mucous membranes become grey/ brown in colour and there is increasing hypotension. The patient may become bradycardic or develop ventricular arrhythmias (Butler, 2011). At this stage prompt, effective treatment may still help the patient although there is a risk of further decompensation.

Answer 95

Irreversible shock – There has been too much cell damage- due to the initial insult and the effects of circulating inflammatory mediators and free radicals from ongoing tissue hypoperfusion and damage. This can lead to systemic inflammatory response syndrome (SIRS), disseminated intravascular coagulation (DIC), multi-organ dysfunction (MOD) and death (Butler, 2011). Patients become increasingly comatose, bradycardic and hypotensive with prolonged CRT and discoloured mucous membranes; respiratory rate and effort decreases leading to decreased PaO2 and increased PaCO2.

Answer 96

acute kidney injury

Answer 97

Acute lung injury?

Answer 98

Acute respiratory distress syndrome

Answer 99

peripheral vasoconstriction leads to decreased perfusion of the mucous membranes therefore they appear pale with prolonged CRT; decreased blood volume results in catecholamine release which causes tachycardia…

Answer 100

decreased blood volume | results in catecholamine release which causes tachycardia…

Answer 101

Clinical signs in patients with hypovolaemic, cardiogenic, obstructive or advanced distributive/ septic shock include1) Impaired mentation- decreased oxygen delivery to neurons 2) Tachycardia (cats may be bradycardic or have a normal heart rate N.B a normal heart rate in a ‘very sick’ cat is likely to be significant- why?) 3) Tachypnoea 4) Pale mucous membranes 5) Prolonged capillary refill time 6) Weak/ absent peripheral pulses (N.B. central pulses will often be normal strength initially. Weak central pulses suggest that the compensatory mechanisms are failing, and the patient is progressing to irreversible shock) 7) Cold extremities 8) Decreased peripheral temperature 9) Decreased rectal/core temperature

Answer 102

Dogs with early septic shock will have similar findings except for: 1) Red mucous membranes due to vasoplegia and pooling of red blood cells in the capillaries 2) Rapid CRT 3) Normal to increased body temp.

Answer 103

Therefore, it is likely that a patient with shock will have increased blood lactate levels which will result in metabolic acidosis.

Answer 104

Increasing blood lactate levels would suggest that the patient’s condition is deteriorating whereas decreasing lactate levels would indicate a return to aerobic respiration due to improved perfusion

Answer 105

Whilst lactate is a useful parameter when considering perfusion, it is important to monitor the trend rather than evaluating a one-off value. One reading shows what the lactate level is at the precise moment the sample is taken – an increased lactate level is associated with poor perfusion. The elevated lactate, however, does not show what the underlying issue is and how that patient will respond to treatment interventions. What is more significant is what happens to the lactate level once treatment starts- I it lowers the patient would appear to be responding; if it remains high/ increases, the patient is not responding and the prognosis becomes poorer.

Answer 106

Increasing PaCO2 and decreasing PaO2/ SpO2 indicate deterioration and worsening of acidosis

Answer 107

The platelet count is often the first haematological parameter to change in DIC, with the count dropping as consumption increases. Therefore, regular reviews of fresh blood smears, performing a manual platelet count each time, can be useful in these patients.

Answer 108

Loss of interstitial fluid leads to a loss of tissue pliability and lubrication. Dehydration can often be first detected on examination of the mucous membranes, although assessment may be confounded by nausea-induced hypersalivation. Findings on physical examination may include depression, dry/tacky mucous membranes and a prolonged skin tent. Body condition score and age should be considered when assessing skin tent. Subcutaneous fat provides greater lubrication than lean tissue and the amount of subcutaneous fat decreases with advancing age. As a result, the cranium and axillary region may provide more information about hydration status than the more commonly assessed scruff. Following retropulsion of the eye of a wellhydrated cat, the nictitating membrane/ third eyelid should immediately return to the normal position; in a dehydrated cat the nictitating membrane is more likely to stick to the globe and slowly slide back.

Answer 109

Several sources agree that the normal PCV can be up to 60-65% in sighthounds and greyhounds Some variations in “normal” PCV need to be considered such as in sighthounds and greyhounds. Due to the large muscle mass and low body fat normally present in these patients, the PCV is usually higher

Answer 110

Depending on the clinical signs that are present, an approximate estimation of the patient’s degree of dehydration may be made. Assessment of PCV and total protein (TP) can also be used to assess the degree of dehydration (Aldridge and O’Dwyer, 2013). In patients that are dehydrated the PCV and total proteins will be elevated due to overall loss of free water leading to haemoconcentration

Answer 111

Assessment of PCV and total protein (TP) can also be used to assess the degree of dehydration (Aldridge and O’Dwyer, 2013). In patients that are dehydrated the PCV and total proteins will be elevated due to overall loss of free water leading to haemoconcentration.

Answer 112

Because of the larger amount of free water present in young animals (<6 months), they are likely to have lower than normal PCV and total protein

Answer 113

In serious or ongoing patients with dehydration, as cells and interstitial fluid become progressively dehydrated, fluid will start to be drawn from the intravascular space due to osmosis- eventually leading to hypovolaemia.

Answer 114

These animals will present with signs consistent with hypovolaemic shock and dehydration. However, an animal that has acute blood loss or is suffering from e.g. GDV will be hypovolaemic but not dehydrated. Dehydration normally occurs over a longer time period and is associated with reduced intake or increased losses. Not all hypovolaemic animals are dehydrated and not all dehydrated animals are hypovolaemic.

Answer 115

``` The most common infectious causes of sepsis in veterinary medicine include: o Septic abdomen o Bite wounds o PyNon-infectious causes include: o Trauma o Burns o Pancreatitis o Surgery o Immune-mediated disease o Neoplasia othorax o Pyometra o Parvoviral enteritis. ```

Answer 116

SIRS is the systemic inflammatory response syndrome: where ‘injury to one organ system might cause damage in others’ (Lewis, 2014). It is a complex condition which can occur secondary to infectious (septic/sepsis) or non-infectious causes. Both Gram-negative and Gram-positive bacteria can initiate the inflammatory response and cause sepsis.

Answer 117

``` Non-infectious causes include: o Trauma o Burns o Pancreatitis o Surgery o Immune-mediated disease o Neoplasia ```

Answer 118

``` It is characterised by changes in the microcirculation to the affected area intended to try to limit the damage- • Increased blood supply to the area • Increased capillary permeability • Fluid exudate • Leucocyte delivery ```

Answer 119

In a patient who develops SIRS, the result of, what should be a localised, inflammatory response becoming systemic is: • Loss of effective circulating volume (due to increased capillary permeability) and vasoplegia caused by inflammatory mediators • Decreased tissue perfusion (due to loss of circulating blood volume) • Interference with cell energy production by mitochondria

Answer 120

Whilst the compensatory anti-inflammatory response could limit the progression of SIRS, in many cases this is also excessive - leading to excessive immunosuppression and immunoparalysis. This predisposes to cell death and further perpetuates the systemic inflammatory response ultimately leading to serious conditions e.g. DIC and multiple organ dysfunction (MOD) and, ultimately, death

Answer 121

Lipopolysaccharide (LPS) is a key component of the cell wall of Gram-negative bacteria and is a potent initiator of the septic inflammatory cascade

Answer 122

The gastrointestinal (GI) and urogenital (UG) systems are the most common sources of Gram-negative bacteria which can lead to sepsis in veterinary patients Leakage of GI contents into the abdomen can occur secondary to ingestion of foreign bodies, enterotomy/biopsy dehiscence, GI neoplasia and perforated ulcers. The leakage of GI contents will result in an extensive inflammatory response and clinical signs resulting from, and associated, with systemic inflammation.

Answer 123

The cell wall of Gram-positive bacteria contains peptidoglycan and lipoteichoic acid that can also activate the inflammatory cascade

Answer 124

Sources of Gram-positive sepsis in | the surgical patient can include wounds and intravenous catheters.

Answer 125

Streptococcus | canis infection can result in toxic shock syndrome and necrotizing fasciitis in the dog

Answer 126

It is characterised by cardiovascular decompensation secondary to widespread vasodilation with inefficient oxygen delivery and resultant cellular dysfunction

Answer 127

o Vasodilation ▪ Leads to hypotension and decreased organ perfusion o Vasoplegia ▪ Loss of vasoconstrictor response to catecholamines/ sympathomimetics o Increased vascular permeability ▪ Leads to interstitial oedema (loss of fluid and albumin into the interstitium) and decreased plasma volume and hypoalbuminaemia Feline patients which develop MOF, often have pulmonary oedema or acute lung injuries which become unresponsive to normal interventions.

Answer 128

Leads to hypotension and decreased organ perfusion

Answer 129

Vasoplegia ▪ Loss of vasoconstrictor response to catecholamines/ sympathomimetics

Answer 130

Increased vascular permeability ▪ Leads to interstitial oedema (loss of fluid and albumin into the interstitium) and decreased plasma volume and hypoalbuminaemia

Answer 131

disseminated intravascular coagulation Activation of primary (platelets) and secondary (coagulation factors) haemostasis leads to formation of micro-thrombi in organs Consumption of coagulation factors and platelets follows- this results in the development of a hypocoagulable state leading to bleeding tendencies (overt DIC) All patients with SIRS (systemic inflammation) have activation of coagulation and hence DIC to some extent

Answer 132

Inflammation leads to activation of haemostatic mechanisms inducing a prothrombotic state (covert DIC).

Answer 133

Activation of primary (platelets) and secondary (coagulation factors) haemostasis leads to formation of micro-thrombi in organs (hypercoagulable) e.g. widespread clot formation- with resultant organ ischaemia due to blood flow being reduced and affected by the presence of clots

Answer 134

o Consumption of coagulation factors and platelets follows- this results in the development of a hypocoagulable state leading to bleeding tendencies (overt DIC) i.e. the clotting factors have been used up and there are none left so the patient will bleed readily.

Answer 135

Renal Dysfunction o Prolonged hypotension may result in renal failure o Dogs in MOF commonly develop acute kidney injuries and azotaemia which worsen over a short timescale.

Answer 136

Pulmonary dysfunction o Both dogs and cats can develop life-threatening pathology of the lungs secondary to SIRS. This is termed acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) o ALI and ARDS occur secondary to the systemic inflammation. This leads to loss of normal pulmonary surfactant and accumulation of protein-rich fluids in the lungs.

Answer 137

Cardiac dysfunction o Septic animals have altered/decreased cardiac contractility and are predisposed to arrhythmias.

Answer 138

Hypotension, micro thrombi and deregulation of regional blood flow can all lead to alterations in gastrointestinal (GI) perfusion.

Answer 139

Increased epithelial permeability, secondary to GI hypoperfusion, can result in bacterial translocation into the lymphatics and blood stream.

Answer 140

Hypoalbuminaemia can result in bowel oedema.

Answer 141

Clinical signs associated with sepsis (or other types of SIRS) include: • Depression • Fever (> 104 F/ 40  C in dogs) o Will become hypothermic in later sepsis • Red mucous membranes and rapid capillary refill time (in dogs) o Later in the disease process the mucous membranes will become pale with a prolonged CRT • Bounding pulse (dogs only) o Late sepsis the pulse will become weak • Tachycardia in dogs • Tachypnoea (RR >40bpm in dogs and cats) • Gastrointestinal signs: o Vomiting Diarrhoea

Answer 142

Clinical signs associated with sepsis (or other types of SIRS) include: • Depression o Septic cats will commonly be hypothermic o Later in the disease process the mucous membranes will become pale with a prolonged CRT o In cats icteric mucous membranes are quite common o Late sepsis the pulse will become weak • Bradycardia in cats • Tachypnoea (RR >40bpm in dogs and cats) • Gastrointestinal signs: o Vomiting Diarrhoea

Answer 143

Heart rate Respiratory rate Temperature Leukogram

Answer 144

<140 OR >225

Answer 145

>20 OR | PaCO2<30 mmHg

Answer 146

< 38.1˚C OR >39.2˚ C

Answer 147

<37.8˚C OR > 40.0 ˚ C

Answer 148

>16-18,000 WBCs / μl | OR <5-6000 / μl

Answer 149

>19,000 WBCs / μl OR <5000 / μl Septic animals may have a leucocytosis (characterised by a ‘left shift’) or leucopaenia.

Answer 150

Currently C-reactive proteins (CRP) can be measured in dogs as a marker for systemic inflammation. C-reactive proteins are released by hepatocytes in response to tissue injury. The concentration of CRP is monitored to identify improving or worsening systemic inflammation. Whilst CRP does indicate the underlying cause of inflammation, it can be a very helpful diagnostic (when SIRS is suspected) and prognostic aid (IDEXX, 2017). Further blood biomarkers may also be developed and used clinically/diagnostically in the future

Answer 151

The compensatory mechanisms (mediated via the HPA and SNS) e.g. increased heart rate and peripheral vasoconstriction are intended to try to maintain circulation to the vital organs; however, the remainder of the body, including the periphery and gastrointestinal tract, will be under perfused

Answer 152

Whilst an adequate circulation to the vital organs is maintained the shock is compensated. If the underlying cause is not identified and managed, the condition will progress with decreasing perfusion of all tissues – decompensated shock As this progresses to late-stage irreversible/ decompensated shock, the prognosis for the patient becomes very poor as increasing cell death and multiple organ dysfunction and failure arise

Answer 153

It is important to remember that shock is a syndrome or condition and NOT a diagnosis. Shock is always a result of a disease or traumatic process (e.g. foreign body obstruction). As such, the bloodwork may reflect the underlying disease process.

Answer 154

The same is true of SIRS and Sepsis. They are complications of another underlying condition. SIRS for example does not occur as a stand-alone condition. There must be an inciting cause.

Answer 155

normal <2.5 mmol/L

Answer 156

Increased lactate leads to metabolic acidosis- i.e. the bloodstream become more acidic (lowered pH). If the patient responds to shock treatment (e.g. IVFT) and tissue perfusion increases, the lactate levels should return to normal; and the metabolic acidosis will resolve as aerobic cellular metabolism is restored.

Answer 157

Septic patients are commonly hypoglycaemic due to increased glucose utilisation and reduced response to cortisol and catecholamines (Chan, 2012). Blood glucose level should be measured in all critically ill patients. In septic patients, glucose will often be low and need to be supplemented so levels should be monitored frequently

Answer 158

Therefore, low blood glucose and increased blood lactate in a patient should highlight suspicion of sepsis - appropriate examination and diagnostics should be carried out to confirm or rule out sepsis

Answer 159

These animals are also commonly hypoalbuminaemic as the vasculitis, which develops with SIRS, leads to protein loss from the vasculature.

Answer 160

Finally, cats will often become mildly to moderated hyperbilirubinaemic (and clinically icteric) when septic.

Answer 161

Frequent patient assessment focusing especially on perfusion parameters e.g. CRT, heart rate, pulse quality, mucous membrane colour, temperature, demeanour, urine output etc. • Frequent assessment for complications e.g. petechiation, prolonged bleeding • Serial blood pressure monitoring is very important (direct or indirect) with appropriate knowledge of what is normal and abnormal • Monitoring delivery of and response to intravenous fluid therapy • Collecting samples appropriately and aseptically for laboratory assessment e.g. blood gases, electrolytes, PCV, WBC, platelets, lactate, clotting times, urinalysis etc. • Monitor ECG tracing for any evidence of abnormalities e.g. arrythmias • Monitoring urine output- due to hypoperfusion the patient may be initially oliguric/ anuric. If it responds to treatment, a normal urine output of 1-2 ml/kg/hr. should return; ongoing oliguria/ anuria would be significant • Pain scoring and monitoring should be carried out in all patients; and repeated as required to monitor the need for analgesia or the response to administered analgesia • Pulse oximetry • Shock index

Answer 162

• Bladder/ urinary catheter/ collection bag care. • Regular turning to prevent decubitus ulcers (every 2-4 hours) • Prevention of aspiration pneumonia • Oral care • Ocular care • Prevention of faecal soiling/ management of rectal foley systems • Passive range of movement techniques • Massage/ coupage/ physiotherapy as appropriate All other nursing needs should be met, and nursing care provided as appropriate to the patient’s condition

Answer 163

Intravenous catheters can be placed for 1. Infusion of fluids (including blood products, as required) 2. Blood sampling 3. Administration of drugs 4. Parenteral nutrition N.B. due to the high osmolarity of what is being administered, this should always be administered through a central line.

Answer 164

``` There are many different types of catheter available for intravenous access (Battaglia and Hirsch-Fitzpatrick, 2016)- ➢ Over-the needle ➢ Through-the-needle ➢ Butterfly/ winged ➢ Peel-away ➢ Over- the- wire/ guide wire ```

Answer 165

Butterfly catheters are useful if patient movement is a potential issue due to the connecting line attached to the catheter. A butterfly catheter is, however, just a needle attached to a piece of extension tubing and port and so can traumatise the blood vessel when in place- consequently, it is not appropriate for long-term use e.g. IVFT

Answer 166

20 drops per millilitre

Answer 167

40-60 drops per millilitre (paediatric).

Answer 168

Product to be administered e.g. total parenteral nutrition should be administered through a central vein

Answer 169

Veins and access points Vein selection- there are various considerations including ➢ Reason for placing the catheter ➢ Anticipated/ likely duration of use ➢ Product to be administered e.g. total parenteral nutrition should be administered through a central vein ➢ Patient factors e.g. central catheter contra-indicated if patient has coagulopathy; ease of access for maintenance etc. Aggressive patients may do better with a catheter placed in the lateral or medial saphenous veins. ➢ Disease process e.g. a hind limb vein is not appropriate in a cat with paraplegia due to aortic thromboembolism; or a patient with gastric dilation and volvulus (GDV) due to the obstructive effect of the enlarged stomach. N.B. Hind limb veins are not recommended in patients in CPA as discussed in Unit 1, Outcome

Answer 170

Standard peripheral venous access is via the cephalic and medial (cats) and lateral (dogs) saphenous veins; the accessory cephalic, auricular vein and dorsal common digital vein are other peripheral veins that could be used as appropriate (Adamantos, 2018). Following appropriate hand hygiene, a large area of hair should be clipped around the vein- especially if a central catheter is being placed; the skin should be aseptically prepared and an aseptic technique used for placement. N.B. sterile gloves are not required for peripheral vein cannulation but should be used for central vein catheterisation. Placement should be as distal in the peripheral vein as possible. Once in the vein, a T port/ Y port and extension set should be attached. Any organic material (e.g. blood) should be cleaned away to reduce risk of infection prior to securing the catheter. A clear sterile film can be used over the insertion site initially as this allows for monitoring of the insertion site for infection and inflammation without removal. The catheter should then be secured with non-elastic adhesive tape/ sterile swabs and then bandaged in place to prevent contamination

Answer 171

A central venous catheter might be placed into a large vein which lies within the thorax or abdomen for various reasons- ➢ Longer term administration of fluids ( > 5 days) ➢ Administration of hypertonic medications/ fluids e.g. > 5% glucose, hypertonic saline ➢ Administration of multiple medications ➢ Requirement for multiple/ serial blood sampling ➢ Administration of total parenteral nutrition ➢ Measuring central venous pressure

Answer 172

``` The lateral (dog) or medial (cat) saphenous vein can be used to introduce a peripherally inserted central catheter, PICC, into the caudal vena cava (Adamantos, 2018). This can be useful if jugular vein access is limited. ```

Answer 173

the patient’s clotting and platelet should be checked prior to placement; a buccal mucosal bleeding time should be performed in patients at risk of Von Willebrand’s disease (

Answer 174

The catheter should be long enough to reach the thoracic inlet so that it will sit just outside the right atrium, in the cranial vena cava. Should be measured to the 4th intercostal space

Answer 175

With the patient in lateral recumbency, the hair is widely clipped over the jugular vein and the skin is surgically prepared. ➢ Sterile gloves should be worn, the site should be draped and a strict aseptic technique adhered to. ➢ A small incision should be made in the skin over the jugular vein. ➢ An assistant raises the jugular vein by applying pressure level with the thoracic inlet. ➢ A standard peripheral intravenous catheter (as the needle is covered by sheath this is the modified technique) (or hypodermic needle) is inserted into the jugular vein. Ensure the needle or catheter is wide enough for the guide wire to thread through ➢ The sterile guide wire provided with the Seldinger kit is inserted through the IV catheter ➢ The IV catheter needle is then withdrawn from the jugular vein, leaving only the guide-wire in place. The guide wire should be held carefully throughout to prevent it disappearing into the vein. At this point, direct digital pressure using a sterile swab will control any haemorrhage. ➢ A dilator (within the kit) is then placed over the guide wire, inserted through the skin and rotated to dilate the subcutaneous tunnel created by the needle. Using the dilator reduces tissue drag as the jugular/ central catheter is introduced into the jugular vein. ➢ The dilator is removed again with the guide wire kept in place. ➢ The jugular/ central catheter is then inserted over the guide wire into the jugular vein. ➢ The guide wire is then removed. ➢ Heparinised saline flushes should be introduced to each port of the catheter and suction applied to remove air from the catheter. ➢ The ports should then be flushed with heparinised saline ➢ The catheter should be sutured in place at the ‘anchor points’, in the wings of the catheter hub. ➢ It should be covered by a sterile dressing. Due to the catheter being sutured to the skin, a very light bandage is needed to cover and protect it. The bandage is not needed to hold the catheter in place. ➢ Following placement, the catheter should be managed aseptically. Ultrasound guided placement of central catheters can be also be performed

Answer 176

Contraindications to placement include coagulopathy, raised intracranial pressure and a prothrombotic state that will predispose to catheter clot formation

Answer 177

The hair is clipped over the jugular (or saphenous) vein with the patient in lateral recumbency. ➢ The skin is aseptically prepared and a small incision is made through the skin over the jugular. ➢ A peel-away, over the needle sheath is placed into the jugular vein and the needle removed leaving the sheath in the vein. ➢ The catheter is then inserted, through the sheath into the vein, and the peel away sheath is grasped and peeled up and out of the jugular leaving the catheter in place. ➢ Care must be taken not to dislodge the catheter during this procedure. ➢ The catheter should be flushed with heparinised saline, if not immediately connected to a drip set, and capped. ➢ The catheter should be sutured in place at the ‘anchor points’, in the wings of the catheter hub. Following placement, the catheter should be managed aseptically, a dressing applied and covered by a bandage.

Answer 178

Dressings around the catheter should be changed every 24 hours or sooner should they become soaked with fluids or soiled, and the catheter site should be checked every 24 hours to identify possible infection or thrombosis

Answer 179

Catheter patency should be maintained by the fluid running throughout – some sources advocate flushing 3-4 times daily (every 6-8 hours). Flushing is required whenever the drip/infusion is halted or if it used intermittently.

Answer 180

A catheter should be removed as soon as it is no longer needed (Adamantos, 2018); however, with excellent maintenance, an intravenous catheter should be able to be kept in place for several days. Removal of a well-managed, functioning, complicationfree intravenous catheter, to minimise the risk of infection, is now NOT recommended after a set period of time (e.g. 3 days)

Answer 181

The catheter site should be checked regularly for any signs of complications e.g. phlebitis with pyrexia, reddening, swelling, pain, discharge or discomfort at the catheter site. N.B. If the patient has pyrexia but no obvious signs of infection at the catheter site, the IV catheter is unlikely to be removed. If there is evidence of phlebitis/ thrombophlebitis or indication of infection, the intravenous catheter may need to be removed, to limit the chance of septicaemia (Adamantos, 2018), so veterinary attention should immediately be sought. If the catheter is removed because of suspected complications, the catheter tip should be retained and stored appropriately in case a culture and sensitivity is indicated.

Answer 182

Other possible complications are- ➢ Thrombosis/ thromboembolism ➢ Infection ➢ Dislodgement of catheter ➢ Catheter embolism – great care should be taken when placing and removing catheters. Scissors should be used with caution near to the catheter. ➢ Air embolism- great care to avoid this with correct set-up, injection technique and use of injection ports ➢ Haemorrhage- the amount of blood loss could be significant depending on the vessel used e.g. a central catheter or an arterial catheter (not discussed in this section. Bruising around the catheter insertion site or excessive blood loss may indicate coagulopathy and should be reported to the veterinary surgeon. ➢ Bandage issues ➢ Pyrexia – this could indicate infection

Answer 183

Fluids, drugs and blood products can all be given via the intraosseous route- although hypertonic fluids and alkaline fluids can cause discomfort

Answer 184

Possible sites for intraosseous catheter placement in the cat or dog are the femur (trochanteric fossa), tibia (medial surface of proximal tibia), humerus (cranial aspect of the greater tubercle) and the wing of the ilium

Answer 185

Skin wound or infection over proposed catheter site, fracture of the bone to be used, pneumatic bones, sepsis and metabolic bone disease

Answer 186

Sterility is of the utmost importance when placing an intraosseous catheter and the skin should be clipped and surgically prepared. The site may be anaesthetised with lidocaine, due to the sensitivity of the periosteum, and a small incision made in the skin. The catheter can then be inserted into the bone and flushed with heparinised saline before connecting T- connector or infusion set. As with intravenous catheters the cannula will need to be secured with sutures or tape and the site covered with a sterile dressing to prevent the cannula from being dislodged. Once in place an X-ray should ideally be taken to ensure that the cannula is present within the marrow cavity.

Answer 187

Intraosseous catheters are typically used in collapsed, hypothermic, hypotensive and hypoglycaemic neonates. The kittens/puppies can then be resuscitated with dextrose and fluids. Usually, within a couple of hours it is possible to attain intravenous access (peripheral or central) and the intraosseous catheter can be removed

Answer 188

Post insertion, the catheter should be managed aseptically and covered with a sterile dressing. Cushioning with a piece of sterile gauze can minimise discomfort before bandaging in place. All handling of the catheter site and flushing should be performed aseptically. Some patients may need the limb to be completely immobilised, using a splint or similar.

Answer 189

Isotonic fluids are very versatile and are commonly used in veterinary practice- for hypovolaemia, dehydration, replacing ongoing losses and maintenance and replacement of electrolytes

Answer 190

Examples include 0.9% | saline, lactated Ringer’s (Hartmann’s) and Ringer’s solution.

Answer 191

0.9% saline might be chosen if a | patient has hypercalcaemia as it increases calcium excretion via the kidney

Answer 192

``` Lactated Ringer’s is likely to be selected when there is a metabolic acidosis as it contains a bicarbonate precursor(common). ```

Answer 193

As they are all relatively/ actually low in potassium, prolonged use can lead to hypokalaemia. None of the isotonic solutions available contain enough potassium to meet maintenance requirements - so most patients will require some potassium supplementation especially if they remain anorexic.

Answer 194

The electrolyte composition of isotonic fluids is similar to extracellular fluid (ECF) - especially lactated ringers which has more potassium than 0.9% saline Because there is no concentration gradient, there is no net movement from or into the vascular space when isotonic fluids are administered

Answer 195

Isotonic crystalloids are the initial replacement fluid choice in most hypovolaemic patients. Isotonic crystalloids will increase intravascular volume and replace interstitial deficits; though the effect is temporary due to capillary fluid shifts. A buffered isotonic crystalloid solution (e.g. lactated Ringer’s solution) may be a more physiologically appropriate resuscitation fluid than normal saline

Answer 196

90ml/kg in dogs

Answer 197

60ml/kg in cats

Answer 198

A mildly hypovolaemic dogs may only require 10-20 ml/kg of isotonic crystalloid

Answer 199

a dog with evidence of severe hypoperfusion i.e. ongoing severe haemorrhage, may rarely require administration of the full 70-90 ml/kg of isotonic crystalloids and, possibly, the addition of colloids

Answer 200

A hypovolaemic cat may respond to a single 10-20 ml/kg bolus of an isotonic crystalloid solution, or may require repeated isotonic crystalloid boluses and, potentially, the addition of a colloid.

Answer 201

Potential issues with administering isotonic crystalloid therapy include prolonging coagulation by dilution; theoretical compounding of acidosis (e.g. 0.9% NaCl is acidic) and causing hypothermia (if using large volume of room temperature fluids). N.B. ongoing blood loss leads to consumption of coagulation factors and platelets that is made worse by the fluid therapy.

Answer 202

A hypovolaemic patient, with decreased peripheral perfusion, will develop metabolic acidosis because of build-up of lactic acid secondary to anaerobic respiration. Administering 0.9% saline could in theory make the acidosis worse as it is an acidic fluid BUT because it increases the blood volume, improves cardiac output and renal glomerular filtration rate (GFR) so perfusion will improve. This means the cells will return to aerobic respiration and should be able to function more effectivelythe lactate levels will decrease and the acidosis should resolve.

Answer 203

80-100ml/kg/day

Answer 204

50ml/kg/day

Answer 205

15-30 | ml/kg/day

Answer 206

These contain bicarbonate precursors, such as lactate, and are used in cases of metabolic acidosis. Within 1-2 hours of administration, the lactate is metabolised into bicarbonate by the liver. The bicarbonate ‘mops up’ hydrogen ions, thus raising the pH and decreasing the acidity of blood.

Answer 207

These contain bicarbonate precursors, such as lactate, and are used in cases of metabolic acidosis. Within 1-2 hours of administration, the lactate is metabolised into bicarbonate by the liver. The bicarbonate ‘mops up’ hydrogen ions, thus raising the pH and decreasing the acidity of blood.

Answer 208

lactate is metabolised into bicarbonate by the liver. The bicarbonate ‘mops up’ hydrogen ions, thus raising the pH and decreasing the acidity of blood. Fluids requiring hepatic metabolism of lactate (e.g. LRS/ Hartmann’s) should not, however, be administered, to animals in liver failure

Answer 209

Sodium bicarbonate will theoretically correct metabolic acidosis but should not be used as a first line treatment to correct the lactic acidosis caused by anaerobic metabolism, seen in animals with hypoperfusion. As a result of fluid administration, perfusion should improve leading to correction of metabolic acidosis. If bicarbonate has been administered additionally, there is a risk the patient will become alkalaemic following fluid therapy. Bicarbonate administration should only be considered if it is possible to perform blood gas analysis; it is only likely to be considered in a patient with acidosis which is non-responsive to other interventions such as appropriate aggressive fluid therapy.

Answer 210

cats- chronic renal failure, prolonged anorexia, muscle wastage and gastro-intestinal losses are potential causes

Answer 211

Hypokalaemia causes muscle weakness, especially obvious in cats, with plantigrade stance and ventroflexion of the neck- it can also cause cardiac arrhythmias.

Answer 212

Hypokalaemia may arise with the increased urine output associated with IVFT, especially if the fluid administered has no potassium e.g. 0.9% NaCL. There may also be reduced serum potassium levels associated with dilution of electrolytes and fluid therapy administration.

Answer 213

The rate of administration should not exceed 0.5 mmol/kg/hour otherwise a cardiac arrhythmia may develop

Answer 214

Monitoring of these patients will focus on ensuring cardiovascular stability (ECG) and adequate tissue perfusion. Heart rate, rhythm, mucous membrane colour, CRT and pulse quality will have to be frequently assessed; as well as temperature checks. Blood pressure and blood work (including PCV/TS and lactate) may have to be frequently monitored, particularly if the patient is haemodynamically unstable e.g. early in the fluid plan, when still hypovolaemic and receiving bolus therapy. Blood gases, acid, base, glucose and electrolyte assessments may also be performed. Patients should have their urine output closely monitored

Answer 215

A variety of treatments will be required when nursing these patients including fluid therapy, analgesia, specific medication and treatment of underlying problems; in addition to monitoring and recording of clinical parameters. The key to treating a patient in septic shock is: • Haemodynamic support o Ensure adequate tissue perfusion and urine output • Remove the septic focus o Surgery for source control o Appropriate antibiosis • Metabolic support o Correct hypoglycaemia o Correct acid-base/electrolyte derrangements

Answer 216

Alpha-1 adrenergic (α-1) Blood Vessel Vasoconstriction

Answer 217

Beta- 1 adrenergic (β-1) Heart Positive inotrope (increased strength) Positive chronotrope (increased rate)

Answer 218

Beta- 2 adrenergic (β-2) Blood Vessels Vasodilation

Answer 219

Dopamine Blood vessels e.g.kidney Vasodilation (other effects elsewhere) (low dose) Vasoconstriction (high dose)

Answer 220

Vasopressor agents (Silverstein, 2006) are commonly needed to maintain normal blood pressure in the septic patient due to vasoplegia. They should not be used at the expense of fluids and normovolaemia must be achieved. The aim of administering vasopressors is to cause vasoconstriction and increase arterial blood pressure.

Answer 221

However, they may also result in excessive vasoconstriction particularly of the splanchnic circulation. This may lead to gastrointestinal ischaemia and dysfunction. It is therefore important to use vasopressors at the lowest dose necessary to maintain arterial blood pressure; and ensure that the animal is normovolaemic. The use of vasopressors will also increase the work of the heart. This added workload, in combination with septic-induced myocardial depression, may require the use of a positive inotrope such as dobutamine.

Answer 222

Many vasopressors need to be administered as a constant rate infusion so small up or down dose adjustments can be made based on the patient’s response. As such it is important to have a reliable method of delivery such as a syringe driver.

Answer 223

Noradrenaline is a catecholamine with potent α-adrenergic but little β-adrenergic activity It has pronounced vasoconstrictive effects on the blood vessels at typical dosages of 0.1-0.3 μg/kg/min

Answer 224

However, due to sepsis induced vasoplegia, doses often have to be increased. In a number of open-label trials, noradrenaline has been shown to increase mean arterial pressure (MAP) in patients who remained hypotensive after fluid resuscitation and dopamine. Access to noradrenaline can be limited in the UK but it can be obtained from certain veterinary wholesalers and accident and emergency, if needed.

Answer 225

At low doses of between 5 and 10 μg/kg/min, dopamine exerts predominantly β-adrenergic effects with resultant positive inotropic and chronotropic effects. There is vasodilation of coronary blood vessels, increased force of contraction and increased heart rate. This results in increased cardiac outputand organ perfusion

Answer 226

The α-adrenergic effects of peripheral vasoconstriction (with resultant increase in systemic vascular resistance) occur at doses greater than 10 μg/kg/min: although there is considerable dose overlap particularly with sepsis-induced vasoplegia.

Answer 227

Dopamine therefore increases mean arterial pressure (MAP) by increasing cardiac output and/or systemic vascular resistance.

Answer 228

It is important to carefully monitor blood pressure in patients receiving dopamine. It is also sensible to use an ECG as arrhythmias may develop. It is administered as a CRI with dose being titrated according to effect. The dose is often limited by tachyarrhythmia in dogs- these typically respond to a dose reduction.

Answer 229

Dobutamine is a direct- acting synthetic catecholamine. It has direct β-1 adrenergic agonist effects and mild β-2 adrenergic and mild/ no α- 1 adrenergic effects. This results in increased heart rate (so increased output) but with little effect on peripheral blood vessels.

Answer 230

It is a potent and short-acting drug so needs to be titrated to effect with careful patient monitoring- especially blood pressure and heart rhythm. As with all sympathomimetics, it may cause tachyarrhythmias

Answer 231

Vasopressin causes vasoconstriction through V1 receptors that are present on vascular smooth muscle

Answer 232

Vasopressin has started to be used in veterinary medicine but should only be used if a septic patient has failed to respond to noradrenaline and/or dopamine

Answer 233

In addition to the direct vasoactive effects of vasopressin, it also increases the responsiveness of the vasculature to catecholamines and inhibits nitric oxide production: nitric oxide causes vasodilation.

Answer 234

Intravenous antibiotic therapy should be administered as early as possible and within the first hour of recognition of septic shock.

Answer 235

Empiric antibiotics should be started in a septic patient, whilst waiting for the culture results and susceptibility testing. The choice of initial antibiotic should be made based on the likely infectious agent and the local patterns of antibiotic susceptibility. Changes can be made to the protocol following identification of the organism and the antimicrobial susceptibility. Recent human studies have demonstrated that patient survival is increased if early antibiosis is instigated- ideally this should be within an hour of recognising septic shock

Answer 236

Septic patients are commonly hypoglycaemic and will typically require dextrose supplementation

Answer 237

An intravenous bolus of 0.5g/kg of dextrose can be administered over 5-10 minutes. Supplementation of maintenance fluids with 2.5% or 5% dextrose may then be necessary.

Answer 238

High-dose corticosteroids were historically administered to patients with sepsis or septic shock due to their anti-inflammatory effects, and reports of an ability to stabilise membranes. The use of high-dose corticosteroids remains controversial in veterinary patients but there is currently insufficient evidence to recommend their use in patients with severe sepsis or septic shock.

Answer 239

Nutritional support is important in all critically ill animals. Approach to nutrition should be proactive in septic animals, and “waiting to see if a patient eats” is not acceptable practice. Benefits of enteral over parenteral nutrition are well documented in people, although many septic patients will not tolerate enteral feeding. Enteral nutrition via a nasoenteric (oesophageal, gastric or jejunal) or surgically placed feeding tube (oesophagostomy) should be considered in all septic patients that can tolerate enteral feeding, have no contra-indication to placement of a feeding tube and are not meeting their resting energy requirements (RER). Use of the GI tract should be avoided in those patients that are hypotensive or require vasopressors so total parenteral nutrition (TPN) may become a possibility

Answer 240

non-steroidal antiinflammatory drugs (NSAID) compromise renal perfusion and can result in GI ulceration and as such should be avoided in septic patients.

Answer 241

Ulcer prophylaxis with an H2 receptor antagonist (e.g. ranitidine) or proton pump inhibitor (e.g. omeprazole) may be administered to a patient with severe sepsis to prevent upper GI bleeding. The 2018 ACVIM consensus statement (Marks et al., 2018) reviews the use of gastro-intestinal protectants. The evidence base for some gastrointestinal protectants is very poor with no proven benefit shown for some. Proton pump inhibitors seem to be more effective than H2 receptor antagonist for ulcer prophylaxis however long-term use of PPIs in people and animals can be harmful.

Answer 242

The correct answer is: 94%

Answer 243

The correct answer is: End tidal CO2

Answer 244

The correct answer is: 7.35-7.45

Answer 245

The correct answer is: Urine output < 1mL/kg/hr

Answer 246

(This estimates the effectiveness of gas transfer from the alveoli to the circulation- it indicates the difference in oxygen levels between the alveoli and the blood leaving the left ventricle - assumed to be the same as blood in the pulmonary capillaries. The Arterial- alveolar gradient indicates the effectiveness of oxygenation rather than the effectiveness of ventilation. N.B. ensure you understand the difference between oxygenation and ventilation. ) The correct answer is: < 15 mmHg

Answer 247

( N.B. Please ensure you are know the technique for performing CVP measurement; and understand what CVP results indicate in veterinary patients. Please review indications and contraindications for placement of a central venous/ jugular catheter. Review best practice nursing care of a central venous/ jugular catheter.) The correct answer is: 0-5 cm H2O

Answer 248

(N.B. Please ensure you consider factors that can affect the blood pressure readings in patients. Ensure you know and understand the methods for recording blood pressure in veterinary patients and consider the advantages and disadvantages of each method.) The correct answer is: Total protein/ total solids in blood

U1 O2 - Shock, vascular access and fluid therapy Flashcards

Shock, Vascular access and fluid therapy