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94 Cards in this Set
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- Back
- 3rd side (hint)
What is the definition of shock?
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Shock is the CLINICAL STATE that develops when tissue OXYGEN DELIVERY, or utilization, is compromised
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What does the amount of oxygen delivered depend on?
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Cardiac output
Concentration of oxygen |
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What does cardiac output depend on ?
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HR x SV
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What do oxygen concentrations depend on?
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hemoglobin and hemoglobin saturation of oxygen
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What are the 4 categories of shock?
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1) Hypovolemic
2) Cardiogenic 3) Distributive 4) Hypoxic |
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What are the 2 causes of hypovolemic shock?
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1) Hemorrhagic
2) Nonhemorrhagic (e.g. third space losses, severe dehydration, urinary losses, severe vomiting/ diarrhea |
Wh
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What are the two types of cardiogenic shock?
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1) Systolic failure
-e.g. CHF, DCM, mechanical defects) 2) Diastolic failure -HCM, tamponade, tension, pneumothorax |
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What are 4 causes of distributive shock?
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1) Sepsis
2) Anaphylaxis 3) Drugs 4) Neurogenic |
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What are 4 causes of hypoxic shock?
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1) Hypoxemia
2) Anemia 3) Methemoglobinemia 4) Carbon monoxide poisoning |
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Overall, why is shock so bad?
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Hypoxia---> altered cell membrane ---> organ fail---> death
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Hypoxia -----> __________-----> ANAEROBIC METABOLISM
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Blocks pyruvate entry into Kreb's cycle
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Why does HYPERLACTEMIA develop during shock?
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Lactate produced by anaerobic glycolysis can't be recycled into pyruvate or glucose without oxygen
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Why does METABOLIC ACIDOSIS develop in patients in shock?
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H+ is produced as a result of ATP---> ADP and can't be used by the mitochondria w/o oxygen
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What happens to the cell in response to a lack of ATP within the cell?
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Loss of electrical and chemical gradients---> CELL SWELLING, INFLAMMATION, DEATH
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What do dangerous associated molecular patterns (DAMPs) result in during shock?
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INFLAMMATORY RESPONSE
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Why do coagulopathies develop early in the course of shock?
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Endothelial damage and exposure of collagen--> endothelial release of tPA, protein C etc.
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What happens when oxygen returns in shock patients?
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REPERFUSION INJURY
-reactive oxygen and nitrogen species -"no reflow" phenomenon |
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What detects the decreased blood pressure in shock patients?
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Baroreceptors (carotid body & aortic arch)
Low pressure stretch receptors (atrial & pulmonary artery) Chemoreceptors |
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What happens when the baroreceptors and low pressure stretch receptors detect low vascular pressure?
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Sends signal up the sympathetic nerve causing:
-Constrict arterioles--> increased SVR --> redirects blood to vital organs -Constrict the veins/venules---> increased venous return ---< increased CO & increased HR |
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What will be the clinical signs of shock in response to the sympathetic stimulation?
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Pale mucous membranes
Increased CRT Cool extremities |
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What do the carotid and aortic bodies sense in the periphery? In the medulla?
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Periphery: sense decreased O2
Medulla: sense increased H+ in CSF and Increased CO2 |
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What happens when the chemoreceptors detect decreased oxygen or acidosis?
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sympathetic nerve causes:
-increased ventilation---> decreased CO2 and decreased H+ (blows off CO2) **Leads to altered respiratory pattern (tachypnea) |
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What are the 4 neurohormonal responses from the sympathetic nerve stimulation during shock?
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1) Renin-angiotensin-aldosterone system
-resorbs H2O & Na from kidney 2) Vasopressin 3) Hypothalamic-pituitary-adrenal axis -CRH---> ACTH--> cortisol -Also epinephrine, glucagon &GH -catabolic state increases glucose for fight or flight 4) Splenic contraction -increases RBCs |
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What are 2 causes of activation of the renin-angiotensin-aldosterone system?
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1) Decreased stretch in the glomerular afferent a. & decreased [Na] in macula densa
2) Directly by sympathetic n. |
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What are the 2 affects of vasopressin release in shock patients?
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1) Aquaporin-2 channels resorb water
2) Direct vasoconstriction |
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What is the "passive response" of the body to shock (in response to decreased MAP)?
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Decreased MAP--> decreased hydrostatic pressure in capillaries
-fluid shifts from interstitial--> intravascular space |
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What drives oxygen diffusion?
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Reduced cellular PO2 tension
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What are the 3 clinical stages of shock?
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1) Compensatory phase
2) Early decompensatory phase 3) Late decompensatory phase |
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What is the compensatory stage of shock?
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Hemodynamic parameters are stable
Hypermetabolic state and high energy expenditure |
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What is the early decompensatory phase of shock?
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Compensatory mechanisms begin to fail
-Blood flow is preferentially redistributed to vital organs |
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What are the 5 things occurring during the late decompensatory phase of shock?
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1) Autoregulatory escape
2) Vasodilation prevails over sympathetic -mediated vasoconstriction 3) Cardiovascular collapse 4) Cardiopulmonary arrest imminent 5) Poorly responsive -body has just given up |
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What compensates during class I of acute blood loss? What are the clinical signs of class I acute blood loss?
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Transcapillary refill from interstitial fluid
Clinical signs or manifestations are minimal or absent |
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What are the 4 clinical signs of class II acute blood loss?
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1) Resting tachycardia
2) orthostatic changes in HR, BP 3) decreased urine output 4) agitated mental state |
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The Class II correlates to the "________ phase" and maybe entering the "_________ phase".
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Compensatory phase
Early decompensatory phase |
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Class III of acute blood loss marks the onset of what?
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Hypovolemic shock
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What are the clinical signs present with class III acute blood loss?
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Worsening decrease in BP, decrease urine output and possibly anuria
-Tachycardia- vasoconstrictor response may be lost at this stage |
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Class III of acute blood loss correlates with the _________ phase.
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Early decompensatory phase
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Class IV of acute blood loss foreshadows what?
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Circulatory collapse, severe and immediately life-threatening
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Class IV of acute blood loss correlates with the _______ phase.
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Late decompensatory phase
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What is the total blood volume in a dog and cat?
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TBV= 90 m/kg in dogs and 60 mL/kg in cats
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What are 3 causes of septic shock?
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1) gram negative bacteria endotoxins (LPS)
2) Gram positive--> exotoxins 3) Systemic or severe fungal infections |
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What is the definition of endotoxemia?
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Presence of endotoxins in the blood---> Cytokine activation and secondary free radical formation, histamine release, complement, platelet activating factor, kinins, etc
-can lead to other 3 forms of shock |
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What is SIRS?
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Systemic inflammatory response syndrome- the criteria that a patient has to meet to conclude they have sepsis
-every specie has a different response to shock -temperature, HR, RR, WBC |
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What are the 5 easy steps to treating shock?
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1. Brief history, PE and measure BP
2) Simultaneously: -Place IV catheter, get sample for initial labs (big 4, lstat, CBC, chem, UA +/- coags, +/- blood gas etc -Start immediate and aggressive supportive case (most likely IV fluid therapy, except if cardiac) 3) More history and PE 4) Focused diagnostics -Aus, CT, CSR, echocardiogram, serum titers, etc. 5) Treat underlying cause |
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True or false. Shock is a primary condition.
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False, that's why history is so important so can identify the underlying cause of shock
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How should you approach doing physical exam for shock patients?
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Do an abbreviated exam initially, then keep re-visiting
-Signs may be subtle: mild tachycardia, pulses may feel particular "strong" (wide pulse pressure) -May be alert, appropriate, ambulatory -If decompensating signs are more classic |
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Dysfunction of "shock organs" means dysfunction of what 2 things?
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GI tract, lungs
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What should you do if you suspect cardiogenic shock?
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Check for jugular vein distension
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Are cats in shock bradycardic or tachycardic? Hyperthermic or hypothermic?
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Tachycardic
Hypothermic |
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What are 2 ways to assess hemodynamics?
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1) Blood pressure
2) Central venous pressure |
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What are 2 non-invasive methods used to measure BP?
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1) Doppler
2) Oscilometric -unreliable if < 5 kg |
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What is the gold standard to measuring BP?
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Invasive BP: arterial catheter
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What is the goal mean arterial pressure for small animals? Systolic arterial pressure?
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MAP >60 mm Hg
SAP > 90 mm Hg |
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What do you want to look at when evaluating the central venous pressure?
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Trends are helpful, absolute values less helpful
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What is considered cardiogenic shock when evaluating CVP?
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> 10 cm H20 drop
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Fluid overload is rare in what animal?
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Horses
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What are 4 ways to perform metabolic assessment?
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1) CBC/chem
2) Big4 (PCV/TS/BG/Azo stick) 3) Istat8+ (lytes & acid base) -can run arterial blood gas 4) Lactate |
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What are 2 ways to assess oxygenation?
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1) Arterial blood gas
2) Pulse oximetry (SpO2-saturation of hemoglobin) |
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Pulse oximetry may be inaccurate so you should correlate the results with what 3 things?
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HR, RR, MM color
-Just because saturation is good doesn't mean high PaO2 |
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What should you do if SpO2 is low or borderline?
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Administering flow of O2 will never hurt and may be life-saving especially if cardiogenic shock
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How should fluids be administered?
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IV or interosseous- never SQ or IM or oral
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What are the 3 general principles of fluid therapy?
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1) Determine volume, type, rate of administration
2) Determine reason(s) for therapy 3) Determine route of administration |
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What are 4 reasons for fluid therapy?
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1) Shock treatment
-60-90 mL/kg depending on species 2) Deficit replacement -estimate % loss x BW (kg) 3) Provide maintenance -~60 mL/kg/day in dogs & cats 4) Ongoing losses: estimated by monitoring -TPR, PCV/TS, urine output, vomiting and/or diarrhea, lactate, blood gas analyses |
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What are 4 examples of isotonic crystalloids?
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1) LRS
2) Normosol-R 3) 0.9% NaCl 4) Plasmalyte -A |
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How is 0.9% NaCl different from the other 3 isotonic crystalloids?
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Lacks a buffer and is acidifying
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True or false. Do not use isotonic crystalloids for maintenance fluids.
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True
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What is the shock dose of fluids for dogs? Cats?
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Dogs: 60-90 mL/kg
Cats: 40-60 mL/kg |
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How should you administer isotonic crystalloids for a shock patient?
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Give 1/4 to 1/3 IV rapidly over ~ 5 minutes, re-assess +/- repeat bolus +/- finish dose over 45-60 minutes
-KEEP REASSESSING PATIENT |
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****Within 30 minutes how much of the infused crystalloids are still present within the intravascular space?
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25% of dose
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Is hypertonic saline usually used in LA or SA medicine?
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LA
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What is the hypertonic saline used for fluids? What is the max dose?
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7.5% NaCl max dose 4 mL/kg
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What are the effects of hypertonic saline on the vascular system?
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-Increases circulating volume by 2-4 x the amount given
-Raises BP, improves CO, lowers SVR, improves O2 delivery |
Hy
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Hypertonic saline may decrease _________ and therefore subsequent multiple organ failure.
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Ischemia/ reperfusion injury
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Where does water shift when an animal is given hypertonic saline?
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Shifts water into plasma from RBCs and endothelium, then from interstitial space and cells
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How do you administer hypertonic saline?
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MUST give crystalloids to replace the resultant fluid deficit
-Give 10 x the amount of hypertonic saline in crystalloids e.g. 10 L of isotonic fluid w/ 1L of hypertonic saline |
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What are 3 examples of synthetic colloids?
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1) Hetastarch
2) Voluven 3) Dextran-70 |
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**How do you administer synthetic colloids?
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NEVER ALONE-always w/ crystalloids
-5-10 mL/kg IV bolus and repeat as needed |
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What patients do you use synthetic colloids on?
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Hypoproteinemic patients w/ low cardiac output
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What is the max dose of synthetic colloids per 24 hour period?
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20-30 mL/kg / 24 hours in dogs and cats
-except voluven |
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What is the half life of synthetic colloids?
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~25 hours
-last longer than crystalloids |
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What animal is more sensitive to fluid overload via synthetic colloids?
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Cats
-Be more conservative in total volume used |
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What are 3 blood products that can be used in small animal medicine?
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1) Fresh frozen plasma (FFP)
2) Packed RBC (pRBC) 3) Whole blood |
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What does fresh frozen plasma provide the patient with?
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Coagulation factors
Increases cardiac output |
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How should fresh frozen plasma be administered? How much?
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10-20 mL/kg given IV over 4 hours
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What is the difference b/w fresh frozen plasma and frozen plasma?
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Frozen plasma has been thawed and re-frozen and lacks most of the coagulation factors FFP contains
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What are packed RBCs used for?
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To replenish oxygen carrying capacity of the blood by increasing RBC mass (PCV)
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When should you recheck the PCV when using packed RBCs?
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~1 hour post-transfusion
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When is whole blood the best choice?
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If available, when the patient needs both packed RBCs and fresh frozen plasma (coagulation factors and oncotic pressure)
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Electrolyte and acid-base imbalances should be treated based on what?
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Results of metabolic monitoring and repeat tests frequently to assess response to treatment
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Should you recheck electrolyte and acid-base status before or after fluid treatment?
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recheck after because fluid treatment almost always will have corrected many if not all of the initial derangments
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When do you administer vasopressors IF they're needed?
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AFTER adequate volume re-expansion: CVP and/or full shock dose of crystalloids and maxxed out colloids
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When should you administer antibiotics to shock patients?
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If suspect septic, once stabilized--> get C & S and start empirical antibiotics
-Consider gram-stain |
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When are steroids used for shock?
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Low-dose glucocorticoids controversial
-even in addisonian hypovolemic shock, steroids are not immediately life saving High-dose glucocorticoids for tx of shock is ineffective or even harmful and strongly contraindicated |
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What is the only type of shock that fluids should NOT be used for?
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Cardiogenic shock
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