In hyperdynamic shock, does cardiac output increase or decrease?

Question

I know that vasodilation decreases vascular resistance and that cardiac output has to INCREASE in order to maintain the mean arterial pressure and offset that decrease. So, stroke volume would increase because of decreased resistance, but doesn't the vasodilation also decrease preload? Which one takes precedence: the decrease in afterload or the decrease in preload (since the former increases stroke volume and the latter decreases it)? Thanks!

Answer 1

The word "hyperdynamic" itself infers a CO increase. In this phase pulses are bounding and cap refill is instant, but as preload decreases because of fluid shifts and the myocardium looses contractility secondary to acidosis and electrolyte imbalances the CO EVENTUALLY does begin to drop and cold shock and death ensue.

Maintaining CO requires massive fluid resuscitation sometimes >100cc/kg , inotropic support, hydrocortisone drip, Ca Mg KCl Phos replacement, NaHCO or THAM, intubation with P&S and prompt initation of ABX therapy. If MSOF occurs then CVVH, HD, ECMO, balloon pump may be indicated

mikedotcom is INCORRECT that hypotension (in this scenario) equates with low CO.

Answer 2

The second phase of shock, after the hyperdynamic phase, manifested by:

systemic hypotension,

<<<reduced cardiac output>>>

, hypothermia,

rapid irregular pulse,

prolonged capillary refill time

and pale mucosae.