Cardiovascular Critical Care II

ii.

Early evidence suggested significant benefit for primarily shockable (VF/pVT) OHCA (N

Engl J Med 2002;346:549-56; N Engl J Med 2002;346:557-63; Circulation 2010;122:S768-

786). A meta-analysis demonstrated a similar nonsignificant reduction in mortality and poor

After exclusion of one trial that allowed for temperature control in the control arm, there

was a significant reduction in poor neurological outcome when implementing temperature

control. A Cochrane analysis found that conventional temperature control compared with no

temperature control conferred the benefit of favorable neurological outcome and survival with

only a slight increase in the incidence of pneumonia and hypokalemia (Cochrane Database Syst

Rev 2016;2:CD004128). The Targeted Temperature Management 2 (TTM2) study, published in

2021 comparing goal temperature of 33°C with normothermia (N Engl J Med 2021;384:2283-

94), found similar outcomes surrounding neurologic function and overall survival. This has led

some to advocate for normothermia (i.e., avoidance of fevers) versus hypothermia. In addition,

in the TTM2 study, patients who underwent therapeutic hypothermia had more adverse events.

iii.

Evidence for nonshockable rhythms IHCA and OHCA has conferred results similar to those

in early studies of shockable rhythms demonstrating increased survival and better neurological

outcomes (N Engl J Med 2019;381:2327-37; Circulation 2015;132:2146-51).

iv.

Optimal targets, timing, duration, and other variables still unclear:

instead of 33°C may be equivocal (Circulation 2015;132(suppl 2):S315-S367; N Engl J

Med 2013;369:2197-206; N Engl J Med 2002;346:549-56; N Engl J Med 2002;346:557-

63; Circulation 2024;149:e254-73). Additional investigations have found that targeting a

warmer temperature (36°C) may lead to reduced times in goal temperature range but with

increased fever rates (Resuscitation 2017;113:39-43). Similar results have been found in

study, as mentioned earlier, has led some to consider strict avoidance of hyperthermia,

using active maintenance of normothermia instead of targeting hypothermic temperature

goals (N Engl J Med 2021;384:2283-94). European guidelines suggest a more modest

application of literature and suggest avoiding fever while continuously monitoring core

did not seem to confer any benefit compared with a 24-hour duration in a multicenter

optimal duration of temperature control.

temperature attainment within 6–8 hours; however, several retrospective studies have not

confirmed the timing of initiation or the timing of temperature attainment as predictors

of neurologic outcome (Acta Anaesthesiol Scand 2009;53:962-34; Int J Cardiol 2009;

133:223-8). Intra-arrest temperature control is currently being investigated, but human

data is limited. Prehospital infusion of cold intravenous fluids for OHCA in several

randomized controlled studies conferred no benefit and may increase the number of

complications; thus, it is not recommended (Circulation 2015;132(suppl 2):S315-S367;

Circulation 2016;134:797-805).

devices, ice packs/bags, cooling blankets, iced isotonic fluids, and/or extracorporeal

membrane oxygenation.