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
