shock and heart failure Flashcards
what causes cardiogenic shock
- depressed myocardial function
- inability of cardiac filling from arrhythmias, occlusions, infarct
what causes hypovolemic/hemorrhagic shock
- depleted body fluids, reducing blood volume
- hemorrhage, burns, diarrhea, vomiting
what causes anaphylactic shock
- allergic reaction resulting in peripheral vosdilation and increased microvascular permeability
what causes neurogenic shock
loss of vascular tone due to inhibition of sympathetic vasoconstrictor nerves
- severe trauma, deep anaesthesia
what causes septic shock
- infective agents
- produce massive vasodilation
- endotoxins from bacteria
- produce massive vasodilation
successful compensation after hemorrhagic shock involves what mechanisms
- baroreceptors
- RAS
- ADH
- capillary fluid reabsorption
list the baroreceptor reflex response to decreases arterial pressure
- increase SNS
- increase HR and inotropy
- increase TPR and venoconstriction
- vasoconstriction shunting blood away from skin and gut to essential organs
what happens to MAP during failure of compensation s/p hemorrhagic shock
- upswing in MAP, then MAP decreases
- failure induced by severe vasoconstriction of essential beds
- brain, heart, renal
- activates positive feedback loops that will further deteriorate function
illustrate the fatal circulatory failure loop
- severe shock
- severe hypotension and tachycardia
- reduced coronary blood flow
- worsening of shock and acidosis
- further LV depression
- severe hypotension and tachycardia
- can’t restore cardiac function
- severe hypotension and tachycardia
- further LV depression
- worsening of shock and acidosis
- reduced coronary blood flow
- severe hypotension and tachycardia
illustrate the fatal cerebral ischemic loop
- severe shock
- low MAP <60 mmHg
- severe cerebral ischemia
- depression of vasomotor and cardaic brain stem areas
- vasodilation lowers HR
- further decrease in arterial pressure and blood flow
- vasodilation lowers HR
- depression of vasomotor and cardaic brain stem areas
- severe cerebral ischemia
- low MAP <60 mmHg
what is heart failure
- pathophysiological state in which the heart is unable to pump at a rate that the metabolizing tissues require
myocardial depression has what affect on calcium homeostatis
- handling by SR is impaired
- myofilaments less responsive to calcium
- excitation-contraction coupling affected
myocardial depression has what affect on NE stores and beta receptor content
- decreases endogenous NE stores and beta receptor content
myocardial depression has what affect on length depression curve? what does this mean?
- depression of lenght-tension curve
- cardiac muscle cannot respond efficiently to increases in preload (EDV)
failing heart will have what SV compared to a normal heart at the same EDV
failing heart ejects a smaller SV at the same EDV
- curve is shifted down and to the right
failure of which ventricle is the most common
left ventricle
what happens to cardiac output and systolic BP with left sided heart failure
- CO fails (compensatory tachycardia)
- systolic BP is reduced
over time, with left sided failure, what can happen to size of left ventricle
- LV may become dilated
- due to increased ESV and EDV, decreased ejection fraction
what happens to left atrial pressures in left sided failure
pressures in left atrium and pulmonary vasculature increase
how does left sided pressure cause pulmonary edema
- caused by elevated pressures in left atrium and increased pulmonary arterial pressure
- **increases afterload on right ventricle and can lead to right heart failure
what commonly causes right sided heart failure
left sided heart failure
what are some signs of right sided heart failure
- peripheral edema
- hepatic enlargement
- jugular vein distenstion
what compensatory mechanisms are activated in heart failure (not good things)
- renin angiotensin system
- ADH
- sympathetic redistribution of blood flow
