The following is a summary of “Therapeutic hypothermia in patients after cardiac arrest: A systematic review and meta-analysis of randomized controlled trials,” published in the September 2023 issue of Emergency Medicine by Chiu, et al.
For a systematic review and meta-analysis, researchers sought to assess the association between targeted temperature management (TTM) using therapeutic hypothermia (TH) and survival rates and neurological outcomes in patients following cardiac arrest. The analysis aimed to clarify the effectiveness of TH in improving outcomes after cardiac arrest, which has been a subject of conflicting results in prior trials.
The review involved a comprehensive search of online databases for relevant studies published before May 2023. Specifically, randomized controlled trials (RCTs) that compared TH with normothermia in patients post-cardiac arrest were selected for inclusion in the analysis. The primary outcome measure assessed was neurological outcomes, while all-cause mortality was considered secondary. A subgroup analysis based on the initial electrocardiography (ECG) rhythm was also conducted.
Nine RCTs involving a total of 4,058 patients were included in this analysis. The results indicated that patients with an initial shockable rhythm after cardiac arrest experienced significantly improved neurological prognosis with TH (relative risk [RR] = 0.87, 95% CI = 0.76–0.99, P = 0.04). This benefit was particularly evident in cases where TH was initiated within a shorter time frame (<120 minutes) and maintained for an extended duration (≥24 hours). However, it was found that TH did not lead to a lower mortality rate compared to normothermia (RR = 0.91, 95% CI = 0.79–1.05). In contrast, for patients with an initial non-shockable rhythm, TH did not significantly improve either neurological outcomes (RR = 0.98, 95% CI = 0.93–1.03) or survival rates (RR = 1.00, 95% CI = 0.95–1.05).
The current body of evidence, characterized by a moderate level of certainty, suggests that therapeutic hypothermia (TH) may offer potential neurological benefits to patients with an initial shockable rhythm following cardiac arrest, especially when initiated promptly and maintained for an extended period. However, TH did not demonstrate significant neurological or survival advantages for patients with an initial nonshockable rhythm.