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 33Β°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:
| (a) | Goal target body temperature 32Β°Cβ37.5Β°C given data showing that targeting 36Β°C |
|---|
instead of 33Β°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 (36Β°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
| (b) | Duration of at least 12 hours; optimally, a minimum of 24 hours. A 48-hour duration |
|---|
did not seem to confer any benefit compared with a 24-hour duration in a multicenter
optimal duration of temperature control.
| (c) | Initiate temperature control as soon as possible (within 2 hours, if possible), with goal |
|---|
temperature attainment within 6β8 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).
| (d) | Modality for cooling includes feedback-controlled endovascular systems, surface-cooling |
|---|
devices, ice packs/bags, cooling blankets, iced isotonic fluids, and/or extracorporeal
membrane oxygenation.