Intra-Arrest Induction of Hypothermia via Large-Volume Ice-Cold Saline for Sudden Cardiac Arrest: The New York City Project Hypothermia Experience

Therapeutic hypothermia, the standard for post-resuscitation care of out-of-hospital sudden cardiac arrest (SCA), is an area that the most recent resuscitation guidelines note "has not been studied adequately." We conducted a two-phase study examining the role of intra-arrest hypothermia for out-of-hospital SCA, first standardizing the resuscitation and transport of patients to resuscitation centers where post-resuscitation hypothermia was required and then initiating hypothermia during out-of-hospital resuscitation efforts. The primary end points were return of spontaneous circulation (ROSC), sustained ROSC, survival to hospital admission, and survival to discharge. Comparing the cohort of standard hospital-initiated hypothermia (Phase I) with the prehospital-initiated hypothermia via large-volume ice-cold saline (LVICS) infusion (Phase II), no difference was noted for any end point: ROSC (56.4% vs. 53.4%, p = 0.51; 95% confidence interval [CI]: -5.7 to 11.4), sustained ROSC (46.9% vs. 42.8%, p = 0.38; 95% CI: -4.7 to 12.4), hospital admission (44.7% vs. 37.7%, p = 0.13; 95% CI: -1.9 to 15.4), hospital discharge among those surviving to admission (40.0% vs. 28.0%, p = 0.08; 95% CI: -1.5 to 27.8), or neurological outcome among those surviving to discharge (76.0% vs. 71.4%, p = 0.73; 95% CI: -26.9 to 38.7). Patients presenting in ventricular fibrillation were more likely to survive to hospital discharge in both phases, although a trend toward worsened early outcomes (ROSC, sustained ROSC, and survival to admission) with intra-arrest hypothermia was noted in this subgroup. Multivariable regression analyses failed to demonstrate any survival benefit associated with the intra-arrest initiation of hypothermia via LVICS. Our study, the largest study of intra-arrest initiation of hypothermia published to date, failed to demonstrate any effect on survival for out-of-hospital SCA patients, confirming findings of previously published smaller studies. We therefore do not recommend the use of intra-arrest cooling via LVICS infusion as part of routine out-of-hospital SCA resuscitative efforts.