Breaking the ice: therapeutic hypothermia for in-hospital cardiac arrest*.

www.ccmjournal. org 1565 Therapeutic hypothermia (TH) is recommended for postresuscitation management of out-of-hospital cardiac arrest patients who remain in coma (1). Two randomized controlled studies (2, 3) showed that TH not only reduced mortality but improved neurologic outcome in survivors. Since then, reports on safety, efficacy, and feasibility of TH in the community setting (4), as well as cost effectiveness, have been published (5). A meta-analysis of combined studies have estimated that the numbers needed to treat were 7 patients to save one life and 5 patients to improve neurologic outcome (6). Application of TH in nonventricular tachycardia/ventricular fibrillation (non-VT/VF) has generated mixed results, however, with recent data (albeit of lower quality), suggesting benefit in survivors of nonshockable rhythms (7). The impact of TH in postresuscitation care is promising, with reports of reduction in mortality trend since TH became incorporated in the resuscitation guideline (8). In-hospital cardiac arrest (IHCA) occurs frequently (9). Patients who suffer IHCA are typically sicker and with significant comorbidities. In terms of logistics, cardiac arrest in the hospital has the potential advantage—high probability of being witnessed, less downtime, earlier cardiopulmonary resuscitation, high probability of higher quality cardiopulmonary resuscitation by trained personnel, more access to advance cardiac life support drugs, and equipment. However, because patients are typically sick to start with, the possibility of good outcome is often guarded (10). Several studies have reported the use of TH for IHCA (7, 9, 11, 12) with variable results likely due to small sample size, varying patient severity, and poor TH implementation—in one study, only 40% of patients achieved target temperature (11). In this issue of Critical Care Medicine, Mikkelsen et al (13) determined the rate of use of TH after IHCA and the factors that determine the use of TH after IHCA. They also determined whether the use had increased over time since the recommendation was published. The study looked at the multicenter prospective cohort of patients in the Get With the Guidelines Resuscitation database from 2003 to 2009. The authors found that TH was either not initiated (only 2% of patients had TH initiated) or poorly administered (44% of patients treated with TH never achieved target temperature within 24 hr, and 17% had temperature overshoot). The authors found several factors associated with use of TH including younger age, occurrence of cardiac arrest in a nonintensive care unit, in a teaching hospital, and on weekdays. The study suffers from several important limitations, most of which were cited and addressed by the authors including the lack of outcome data and the inability to determine the appropriateness of the use of TH in the available dataset. However, it was not evident why a high proportion of patients treated with TH were outside of target temperature, and no data on the method of hypothermia induction and maintenance were available in the study. Several factors may have contributed to this including the lack of a written institutional protocol, lack of hospital staff familiarity and/or training on TH, and variable use of automatic, computercontrolled closed-loop hypothermia equipment for temperature management. The low rate of use of TH was suspected to be due to lack of good data from randomized trial demonstrating benefit and the uncertain risk of TH in this subset of patients, the lack of resources for implementation of TH including protocols, personnel, and specialists. As expected, significant variability exists among hospitals who participated, with mortality in the range of 6–71%. Whether mortality in hospitals with high TH use is low and whether appropriate patients who received TH and achieved target temperature had good outcome remains to be seen. Additional studies are definitely needed including costeffectiveness analysis and long-term outcome assessment if we expect wider acceptance of TH among intensivists. Despite these limitations, the study is important. This is the largest study that looks specifically on application of TH on IHCA. At the very least, the study offers a glimpse on how we are treating our patients with IHCA. It calls our attention to the unmet needs and wide gap in knowledge in the critical care management of IHCA. The low rate of use of TH in the intensive care is understandable given the significant comorbidities and potentially poor patient prognosis. However, it is interesting to see the extremely low rate of use of TH even in the emergency room (187/6859, 2.7%) and procedure areas (203/6883, 2.9%), and even in patients who had VT/VF as initial rhythm (332/15,720 or 2.1%). In fact, contrary to the authors’ hypothesis, initial rhythm was not found Breaking the Ice: Therapeutic Hypothermia for In-Hospital Cardiac Arrest*