Use of prehospital-induced hypothermia after out-of-hospital cardiac arrest: a survey of the National Association of Emergency Medical Services Physicians

Abstract

Objective: Postresuscitation care of comatose survivors of cardiac arrest using induced hypothermia (IH) is recommended by the American Heart Association (AHA) and the International Liaison Committee on Resuscitation (ILCOR) to improve neurological outcomes but has been performed primarily later in the course of care. Recently, it was shown that prehospital cooling is feasible, safe, and effective in lowering patient temperature. We sought to determine the prevalence of EMS agencies that use prehospital IH. We also sought to determine what perceived barriers to initiating IH might exist and the understanding EMS physicians have of guidelines for IH.

Methods: We collected a convenience sample of completed questionnaires from physician members of the National Association of EMS Physicians at the national conference on 3 days from January 11 to 13, 2007.

Results: One hundred forty-five (59%) physician members who had attended the conference completed the survey, representing 109 EMS Medical Directors and 36 non-Medical Director EMS Physicians from 92 regions of 34 U.S. states, three Canadian provinces, and one European country. A total of 9 of 145 (6.2%) of physicians stated that the EMS agency they are affiliated with uses a protocols for IH, 6 of whom were local EMS Medical Directors. The median (IQR) duration of having a protocol was 12 months (6-12), and all used either ice bags or cold IV fluid or a combination of the two. Among those who reported prehospital use of IH, only one of eight (12.5%) recall having cooled greater than 10% of eligible patients in the field. Common perceived barriers to IH include the following: overburden with other tasks (62.1%), short transport times (60.7%), lack of refrigeration equipment (60.0%), and receiving hospitals' failure to continue therapeutic hypothermia (56.6%). A small but significant percentage (22.1%) believed that the lack of guidelines specifically addressing prehospital cooling was a barrier to initiating a protocol, and only 62% correctly identified 32-34 degrees C as the recommended target temperature range.

Conclusions: The practice of prehospital IH is rare. Infrequent use of prehospital cooling seen in our select population may be due to the perceived barriers that were identified and/or inadequate guidance from the scientific literature. Statements from the AHA and ILCOR first published in 2003 and reiterated in 2005 recommend the implementation but do not specify the most beneficial time to initiate postresuscitation cooling of comatose survivors of cardiac arrest. Further studies should examine the relative benefit of prehospital cooling.