Shock Flashcards
1
Q
shock
A
- 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
Q
determinants of blood pressure
A
•CO = HR x SV
SV - preload, myocardial contractility, afterload
•TPR (SVR) - vessel length, viscosity, radius
3
Q
hypovolemic shock
A
- 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
Q
cardiogenic shock
A
- 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
Q
distributive shock
A
- 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
Q
common features of shock
A
- hypotension
- systolic <90 mmHg or MAP <65 mmHG - cool, clammy skin
- redistribution by vasoconstriction of blood to vital organs
- distributive shock - sepsis - flushed warm skin - oliguria
- shunting of renal blood flow to vital organs, objective measure of intravascular volume depletion
- orthostatic hypotension is a sign of volume loss - change in mental status
- metabolic acidosis
- accumulation of lactic acid,lactate production increased due to anaerobic metabolism
7
Q
treatment of shock
A
- IV fluids
* vasopressors for MAP <65 mmHg
8
Q
phenyephrine
A
- purely alpha adrenergic
* vasoconstriction –> increase in SVR
9
Q
norepinephrine
A
- alpha 1 and beta 2
- vasoconstriction and an increase in CO
- first line for shock
10
Q
epinephrine
A
- 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
Q
dopamine
A
- 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
Q
dobutamine
A
- 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
Q
vasopressin
A
- sometimes added to norepinephrine therapy in severe refractory septic shock
- only in a fixed dose, not titrated
- vasoconstriction and increased SVR
