Mechanism of shock Blood volume is normally roughly 5 L in a normal adult, and capacitance of blood vessels is nearly 5 L under normal conditions, the same amount of blood i.e 5 L is being pumped by the resting heart every minute, shock occur due to discrepancy between volume and capacity or due to pump failure.
Shock can occur because of volume loss
i.e hypovolemic shock such as in hemorrhage, large burns, or some skin condition like exfoliative dermatitis.
Shock may also occur because of increased vascular capacity, this is called
distributive shock which includes septic, anaphylactic and neurogenic shock whereby blood vessels abnormally dilate causing pooling of blood in periphery.
Another mechanism is
pump failure, this may be due to intrinsic fault in heart muscles like a massive myocardial infarction
(cardiogenic shock), or obstruction to venous return and/or cardiac output as in
cardiac temponade, this is called
obstructive shock,
the above video shows a patient with cardiac temponade.
