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Flashcards in Shock Deck (13)
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1

shock

•physiologic state characterized by a systemic reduction in tissue perfusion resulting in decreased tissue O2 delivery
•initially reversible
•rapidly irreversible --> cell death, end organ damage, failure of multiple organ systems and death
•pre-shock and overt shock

2

determinants of blood pressure

•CO = HR x SV
SV - preload, myocardial contractility, afterload
•TPR (SVR) - vessel length, viscosity, radius

3

hypovolemic shock

•decreased preload
•CO falls when preload drops
•result of hemorrhage and/or other fluid loss (dehydration, pancreatitis)
•CVP down due to loss of fluid
•CO down due to loss of fluid
•SVR up

4

cardiogenic shock

•pump failure
•decreased CO
•cardiomyopathic causes, arrhythmias, severe valvular disease, massive PE, cardiac tamponade and others
•CVP up due to nothing moving
•CO down due to pump failure
•SVR up

5

distributive shock

•vasodilatoryshock
•severe decrease in SVR
•increased CO
•common cause is septic shock, but also includes anaphylaxis and neurogenic shock following CNS injury or spinal cord injury
•CVP down due to vasodilation, or stays the same due to capillary leak of fluid into tissues (forming edema) and pleral and peritoneal spaces (third spacing of fluids)
•CO up due to vasodilation
•SVR down due to vasodilation

6

common features of shock

1. hypotension
-systolic <90 mmHg or MAP <65 mmHG
2. cool, clammy skin
-redistribution by vasoconstriction of blood to vital organs
-distributive shock - sepsis - flushed warm skin
3. oliguria
-shunting of renal blood flow to vital organs, objective measure of intravascular volume depletion
-orthostatic hypotension is a sign of volume loss
4. change in mental status
5. metabolic acidosis
-accumulation of lactic acid,lactate production increased due to anaerobic metabolism

7

treatment of shock

•IV fluids
•vasopressors for MAP <65 mmHg

8

phenyephrine

•purely alpha adrenergic
•vasoconstriction --> increase in SVR

9

norepinephrine

•alpha 1 and beta 2
•vasoconstriction and an increase in CO
•first line for shock

10

epinephrine

•beta 1 and beta 2 and alpha 1
•low doses increase CO because beta 1 inotropic and chronotropic effects, while alpha 1 vasoconstriction offset by beta 2 vasodilation
•at higher doses alpha 1 predominates over beta 2 --> increase in SVR and CO
•first line for anaphylaxis

11

dopamine

•1-2 mcg/kg per minute, acts on dopamine 1 receptors in the renal, mesenteric, cerebral and coronary beds --> selective vasodilation
•2-5 mcg/kg per minute have variable effects on hemodyanmics in individual patients
•5-10 mcg/kg per minute, also stimulates beta 1 receptors --> increased CO
•>10mcg/kg per minute, predominant effect is to stimulate alpha adrenergic receptors --> vasoconstriction and increased SVR
•hypotension due to spesis or cardiac failure, but not first line for either

12

dobutamine

•no vasoconstrictor effects on the peripheral vasculature
•bet 1 receptor producing inotropic and chronotropic effects on the heart
•minimal alpha and beta 2 receptor effects may result in overall vasodilation with decreased SVR
•severe, medically refractory heart failure and cardiogenic shock

13

vasopressin

•sometimes added to norepinephrine therapy in severe refractory septic shock
•only in a fixed dose, not titrated
•vasoconstriction and increased SVR