Clinical Effect of Rebound Hyperthermia After Cooling Postcardiac Arrest: A Retrospective Cohort Study

Therapeutic hypothermia is used in select patients after out-of-hospital cardiac arrest (OHCA) to improve neurologic outcome. Rebound hyperthermia (RH) is commonly observed post-treatment. Previous studies analyzing the association of RH with clinical outcome have reported conflicting results. The purpose of this study is to examine the impact of RH after completion of therapeutic hypothermia in patients postcardiac arrest. We analyzed a retrospective cohort from our institution. All adults who underwent therapeutic hypothermia post-OHCA were divided into two cohorts depending on the presence/absence of fever (T > 38°C) within 24 hours of completing hypothermia protocol. Clinical outcomes were analyzed at hospital discharge or death. Among 306 patients admitted with OHCA, 117 underwent hypothermia, 97 survived 24 hours postrewarming. Twenty-seven patients (50%) with RH died compared with 20 (47%) without RH (OR, 1.15; 95% CI, 0.52-2.57). Twenty-six patients (67%) with RH had a poor neurologic outcome compared with 27 (63%) without RH (OR 1.19, 95% CI, 0.51-2.74). RH is common after completion of therapeutic hypothermia in comatose patients due to cardiac arrest and is associated with poor neurologic outcomes. We found no significant clinical impact of rebound hypothermia on neurologic outcome or mortality, but our study was underpowered to reveal such impact if it exists.