Norkus Text Flashcards
When will you see pale/grey/muddy/white mucous membranes?
Poor peripheral perfusion (vasoconstriction from shock or anemia)
When will you see red mucous membranes?
Carbon monoxide toxicity or states of vasodilation (sepsis, fever, anaphylaxis)
When will you see yellow mucous membranes?
Hyperbilirubinemia; may suggest hemolysis, bile duct obstruction, liver disease, feline sepsis
When will you see blue/purple mucous membranes?
Hypoxemia
When will you see brown mucous membranes?
Methemoglobinemia (i.e. acetaminophen toxicity)
When can you see CRT >2 sec?
During states of poor perfusion
When can you see CRT <2 sec?
Vasodilation (i.e. fever, sepsis, anaphylaxis)
Define lethargic
A patient who is mildly depressed with slightly decreased interaction with environment but patient is easily aroused
Define obtunded
Moderate to severely depressed demeanor and interaction with environment; patient is aroused with some difficulty
Define Stuporous
Patient responds only to vigorous or painful stimulus
Define comatose
Patient does not respond to any stimuli
What is the process by which ATP is produced (under normal conditions)?
Oxidative phosphorylation (of ADP)
Define cardiac output
The volume of blood pumped by the heart each minute
Define stroke volume
The volume of blood pumped by the heart each beat
What is critical oxygen delivery?
In the presence of marked decrease in oxygen delivery to tissue, the body is unable to maintain constant oxygen consumption and will therefore decrease consumption in proportion to delivery of oxygen
What happens below the critical oxygen delivery value?
The body undergoes anaerobic metabolism which results in increased formation of lactic acid
What are the 5 types of hypoxia?
- Hypoxemic hypoxia
- Hypemic hypoxia
- Stagnant hypoxia
- Histiotoxic hypoxia
- Metabolic hypoxia
What is hypoxemic hypoxia?
When inadequate oxygen delivery results from inadequate oxygen carrying capacity of blood secondary to hypoxemia from decreased PaO2 and SaO2
What is hypemic hypoxia?
Also called anemic hypoxia. Anemia causess a decrease in circulating Hb thus reducing CaO2 and DO2
What category of hypoxia does methemoglobinemia and carbon monoxide toxicity count as?
Hypemic hypoxia because although there is an adequate amount of Hb available, it is dysfunctional and unable to transport oxygen (hemoglobinopathy)
What is stagnant hypoxia
Circulatory hypoxia. Caused by low CO and low blood flow. Low DO2 because of low CO
What is stagnant hypoxia clinically referred to as?
Circulatory shock
What is histiotoxic hypoxia?
When there is adequate DO2 but the tissues are unable to extract and utilize the O2 appropriately (i.e. cyanide poisoning, carbon monoxide poisoning or mitochondrial dysfunction of sepsis)
What is metabolic hypoxia?
Increased oxygen consumption (i.e. in sepsis)
Define hypoxia
Inadequate oxygen delivery to meet tissue metabolic demand caused by inadequate tissue perfusion, metabolic disturbance, or lack of O2 supply
Define shock
A state of decreased CO leading to decreased perfusion and inadequate delivery of oxygen to tissue
What are the 4 classes of shock?
- Hypovolemic
- Obstructive
- Distributive
- Cardiogenic
Define hypovolemic shock
Most common form. Decreased intravascular volume from blood or fluid loss (V+/D+/third spacing). Inadequate circulating volume therefore decreased cardiac preload leading to decreased CO
Define obstructive shock
physical obstruction in the circulatory system (i.e. heartworm, pericardial effusion, gastric torsion). Decreased cardiac preload
Define distributive shock
Initiating cause such as sepsis, anaphylaxis and SIRS. Normal blood volume is present but so is vasodilation
Define cardiogenic shock
Results from the inability to eject blood and achieve normal cardiac output (i.e. heart failure). Decreased cardiac contractility, increased afterload, and increased preload
What activates the renin-angiotensin-aldosterone-system (RAAS)?
Decreased renal blood flow
What is the end result of RAAS?
Systemic vasoconstriction; water and sodium retention, which helps increase plasma volume/replace intravascular volume. Improve SV/CO/DO2
Where is renin released from?
juxtaglomerular cells in the kidney
What hormone initially activates RAAS?
Renin
What is the role of renin?
To cleave a peptide from the protein angiotensinogen (produced by the liver) which creates angiotensin 1
Where is angiotensinogen produced?
The liver
What converts angiotensin 1 to angiotensin 2?
ACE (angiotensin converting enzyme)
Where is angiotensin-converting enzyme produced?
Epithelial cells throughout the body
What does angiotensin 2 do?
vasoconstrictor; stimulates the secretion of adrenocorticotropic hormone (ACTH), aldosterone, and antidiuretic hormone (ADH)
What does adrenocorticotropic hormone (ACTH)?
Stimulates the adrenal cortex to release cortisol
What does cortisol do?
Works with epinephrine and glucagon to induce a catabolic state which allows the body to break down reserves for immediate energy needs, stimulates gluconeogenesis, and the generation of glucose from non-carbs (i.e. lactate), creates insulin resistance, and retains sodium and water through the kidneys
What is the body’s main mineralcorticoid hormone and where is it produced?
Aldosterone; in the zona glomerulosa of the adrenal cortex of the adrenal gland
What does aldosterone do?
Vasconstriction; Conservation of sodium in kidney (more water retentino), potassium excretion from kidney
What does antidiuretic hormone (ADH/vasopressin) do?
Vasoconstrictor; Increases water permeability within the kidney by insertion of aquaporin 2 channels within the cortical collecting duct of the kidney (decreases water losses)
What are the 3 stages of hypovolemic shock?
Compensatory, early decompensatory, late decompensatory
What is compensatory shock?
The bodies response to the initial injury; body tries to preserve vital organs by constricting the peripheral blood vessels (and the spleen)
What are the signs of compensatory shock?
PCV can be normal to high; cold extremities; tachycardia; injected mm with rapid CRT; bounding pulses; BP can be normal to slightly elevated
Do cats display compensatory shock?
No
What is early decompensatory shock?
The bodies response after moderate decreases in intravascular volume; the body’s reserves are being depleted and cytokines from hypoxic tissues are more pronounced
What are clinical signs of early decompensatory shock?
Tachycardia; weak pulses; hypotension; pale mm with prolonged CRT; hypothermia; cool extremities; increased RR/RE; decreased mentation
What treatment is important during early decompensatory shock?
Aggressive fluid resuscitation
What is late decompensatory shock?
Final and terminal stage of shock, brought on by prolonged and severe tissue hypoxia causing ATP depletion, anaerobic metabolism, and cell death
What are the clinical signs of late decompensatory shock?
Bradycardia; severe unresponsive hypotension; pale or cyanotic mm; undetectable CRT; weak or absent pulses; hypothermia; decreased or comatose mentation; cardiac arrest
Define hypoxemia
A low concentration of dissolved oxygen in the blood (i.e. an arterial partial pressure of oxygen below 80 mmHg)
What are the 5 causes of hypoxemia?
- Decreased inspired partial pressure of oxygen (PiO2)
- Hypoventilation
- Ventilation/perfusion (V/Q) mismatch
- Diffusion impairment (rare)
- Anatomical shunting
What is the fraction of inspired oxygen (FIO2) in room air?
21%
What are the oxygen flow rates for a patient with a standard nasal cannulae?
50-150 mL/kg/min
What can happen if you exceed the standard flow rates for patients with nasal cannulae?
Gastric distension, drying of mucous membranes, patient discomfort
What is the maximum flow rate of oxygen for a patient on intratracheal oxygen?
0.5 L/min
What are the consequences of exceeded the maximum oxygen flow rate for a patient on intratracheal oxygen?
the tube can oscillate and irritate the trachea; or over distension of the lungs
What is the FiO2 range for flow by oxygen?
30%-60%
What is the FiO2 maximum for high flow?
Almost 100%
What is rapid sequence intubation (RSI)?
Quickly inducing general anesthesia to facilitate intubation (i.e. using alfax or propofol). Can be used in cases where a resp distress patient has failed to respond to initial tranquilization with butorphanol
How many forms of lactate are there and what are they?
2; L- and D-lactate
Which stereoisomeric form of lactate does an in house plasma lactate measuring device measure?
Both L- and D-lactate
Which stereoisomeric form of lactate is more predominant and functioning?
L-lactate
Where is lactate produced?
Skeletal muscle, brain and adipose tissue, and circulating blood cells
Where is lactate metabolized?
Liver, kidney, myocardium
When will plasma lactate increase?
When its production by hypoxic tissues overwhelms its elimination by the liver
What is the normal range for plasma lactate in dogs and cats?
2.5 mmol/L in dogs and 2.5 mmol/L up to potentially 5 mmol/L in cats
What are the classes of hyperlactatemia?
Type A and type B
What is type A hyperlactatemia?
States of hypoxia and anaerobic metabolism (hypoperfusion, anemia, severe hypoxia, CO toxicity, seizures/tremors, patient struggling or exercise)
What is type B hyperlactatemia?
Results from systemic disease, drugs or toxins, or inborn congenital disease of lactate metabolism (type B1, B2, and B3 respectively)
What are examples of type B1 hyperlactatemia?
Systemic diseases like diabetes mellitus, neoplasia, hepatic failure, and sepsis/SIRS
What are examples of type B2 hyperlactatemia?
Drug or toxin exposure like corticosteroids, glucose, xylitol, endogenous or exogenous catecholamines like epinephrine, lactulose, and ACE-inhibitors
What are examples of type B3 hyperlactatemia?
Inborn congenital disease of lactate metabolism. Uncommon but have been seen in GSD, JRT, Old english sheepdogs, and spaniels
What is the shock index?
A bedside assessment of evaluating severyity of hypovolemic shock
Solutions of greater than how many milliosmoles should only be given through a central venous catheter?
> 600 mOsm
What is Virchow’s triad?
Proposes that all causes of thrombosis occur due to the presence of one or more of the following three factors:
1. endothelial damage
2. Blood stasis/turbulent blood flow
3. Hypercoagulability
What is another name for systemic vascular resistance?
Total peripheral resistance
What is arterial blood pressure?
The product of CO and SVR
What causes the doppler shift?
The re-entry of blood into the artery following deflation of the blood pressure cuff
What is the Beer-Lambert law?
Associates the intensity of light transmitted through a solution to the solution’s concentration. It is the principle that pulse oximetry works on.
What is SpO2?
The amount of light absorbed at both red and infrared wavelengths . This absorbance is expressed as a percentage of oxygenated hemoglobin to total hemoglobin
What is coronary perfusion pressure (CPP)?
The pressure gradient that drives coronary blood flow. It is the difference between diastolic aortic pressure (DAP) and right atrial diastolic pressure (RADP). An important variable associated with the likelihood of ROSC
What is the minimum presumed CPP for ROSC to occur?
15 mmHg
What are the 3 phases of CPR?
- Basic life support (BLS) = chest compressions
- Advanced life support (ALS) = meds, IV access, monitoring, defibrillation
- Postresuscitative care
What is the ideal compression depth during CPR?
1/3 to 1/2 the width of the chest
What is the cardiac pump theory in CPR?
Blood flow during compressions occurs due to physical compression of the ventricles which is only possible in patients under 7 kg
What is the thoracic pump theory?
In patients over 7 kg, compressions should be performed distal to the heart (where the chest is widest). The movement of blood occurs due to increased intra-thoracic pressure
What are interposed abdominal compressions (IAC)?
Compressions done over the liver by a second rescuer alternating with chest compressions to move blood out of the abdominal cavity. The rate should be 70-90 bpm
What is the purpose of an impedance threshold device (ITD)?
portable, non-invasive units that are place on the end of the ET tube. Decrease intrathoracic pressure during inspiration which allows for venous return and improved CO on the next compression
Why is the use of doxapram no longer recommended in CPR?
It increases the myocardial and cerebral oxygen demand and reduces cerebral perfusion which leads to worse neurological outcomes
Define Myocardium
The musculature and conducting system of the heart collectively
Where do the left ventricle and atrium receive blood from?
The lungs