Cardiogenic Shock Flashcards
What is the definition of shock?
Profound reduction in devlivery of O2 and other nutrients to tissues leads first to REVERSIBLE and then if prolonged to IRREVERSIBLE cell injury
What are the 4 forms of shock?
Cardiogenic
Extracardiac (obstructive)
Hypovolemic
Distributive (septic)
What is the clinical diagnosis of shock?
<90 mm Hg systolic
PLUS
Poor perfusion (CNS = confusion, Skin = cold, clammy)
What are the 3 types of cardiogenic shock?
Large LV MI
RV MI
MR os VSD
What is the definition of filling pressure?
Pressure the atrium must rise to fill the ventricle
aka ventricular end diastolic pressure
How can you measure the filling pressures of the RV and LV?
Swan-Ganz pulmonary artery flotation catheter
What is a normal LV EDP?
<12 mmHg
What is a normal RV EDP?
<5 mmHg
How can the Swan Ganz catheter measure LV EDP?
Floats through RA, RV, to pulmonary capillaries
Blocks capillary and tip measures pressure
This pressure = LA pressure = LV EDP
What is a normal CO?
3.5 - 5.0 L/min
When there is a large LV MI, what happens to the following characteristics:
- LV EDP
- RV EDP
- CO
- Murmur (y/n)
LV EDP - increased
RV EDP - no change
CO - decreased
Murmur - No
In Large LV MI, systolic function (pump function) is bad
What is the prognosis for a patients with large LV MI?
> 90% mortality
What are two ways that the myocardial tissue can “act dead”?
Stunning - blood has reperfused tissue, requires time for muscle to start working again
Hibernating - blood has not yet reperfused
What are ways of maintaining viability of “acting dead” tissue?
Inotropic support
Vasopressors
Mechanical devices - best option
Which drugs can be used to provide inotropic and vasopressor support to try and maintain perfusion in large LV MI?
Dopamine - best option, positive inotrope and causes vasoconstriction
NE - potent vasopressor, give if dopamine inadequate
Dobutamine - should not be used if patient is hypotensive! Causes vasodilation
What mechanical devices can be used to try and maintain perfusion in large LV MI?
Intraaortic balloon pump
Left ventricular assist device
Extracorporal membrane oxygenator
How does the intraaortic balloon pump work?
During diastole - inflate - aortic diastolic pressure increased - fills coronary arteries
During systole - deflate - aortic systolic pressure decreased - LV empties better
When there is a RV MI, what happens to the following characteristics:
- LV EDP
- RV EDP
- CO
- Murmur (y/n)
LV EDP - normal or increased
RV EDP - increased
CO - decreased
Murmur - No
Pump function is bad
Why can the LV EDP be normal or increased when there is a RV MI?
RV MI is due to blockage of right coronary artery, causing inferior wall infarction
RCA supplies the entire inferior wall, including part of the LV
So, in some inferior MIs, see decreased LV function and increased LV EDP
What is the primary way to acutely treat RV MI and why?
Trial of VOLUME
RV is low-pressure pump, contractility depends on preload
When RV is not functioning well, need to raise RA pressure to drive blood into RV and through to the PA
Hence, need to increase volume to increase preload
Why must you titrate the volume in RV MI instead of giving it all at once?
If there is LV damage, increased volume could be detrimental, causing congestion and pulmonary edema
How can you use EKG to determine if there is an RV MI?
ST elevation in leads 2, 3, and avF indicate an inferior wall infarct
BUT, this could also include LV dysfunction. So need to add RIGHT SIDED CHEST LEADS and look for ST elevation and abnormal Q wave
In RV MI, what will happen to the patient if they are given nitroglycerine?
HYPOTENSION
Vasodilation - volume will go to legs, exact opposite of the volume increase needed in RV MI
When there is a VSD or MR, what happens to the following characteristics:
- LV EDP
- RV EDP
- CO
- Murmur (y/n)
LV EDP = increased
RV EDP = normal
CO = decreased
Murmur = Yes
VSD = During diastole blood from RV can go into LV, increasing LV EDP MR = during systole, blood went back into the LA, increasing the amount of volume there. During diastole, this excess volume of blood enters LV, increasing LV EDP
How can you diagnose VSD?
Measure O2 sat in the LV, RV, and RA
Will see oxygen step up in RV since oxygenated blood from LV is coming over
When there is volume depletion, what happens to the following characteristics:
- LV EDP
- RV EDP
- CO
- Murmur (y/n)
LV EDP = decreased
RV EDP = decreased
CO = decreased
Murmur = no
This is hypovolemic shock, not cardiogenic
What type of fluid should be given if the fluid loss is blood loss?
Blood
What type of fluid should be given if the fluid loss is inflammatory plasma loss?
Albumin
What type of fluid should be given if the fluid loss is dehydration?
Electrolytes, saline
What type of fluid should be given if the fluid loss is inanition (lack of food and water)?
Glucose in water
How is MR or VSD cardiogenic shock treated?
Surgery
