The overall goal of this study is to determine the feasibility of initiating hypothermia in cardiac arrest patients as soon as possible in the field. In this pilot study we will randomize 125 patients after return of spontaneous circulation (ROSC) to hypothermia with rapid infusion of 2 liters of 4oC Normal Saline IV solution over 20 to 30 minutes, IV sedation and muscle paralysis or to standard of care following ROSC. The primary objectives of this study will be to determine whether temperature of 33-34oC can be achieved and maintained using this strategy. The primary outcome measures will include: temperature changes of the patients at time of admission to the hospital. Secondary analysis will include determining if the proportion of patients discharged from the hospital is increased in the group receiving hypothermia. If this initial pilot study can demonstrate feasibility in achieving and maintaining hypothermia, a larger randomized clinical trial to test the hypothesis that hypothermia initiation in the field will increase the proportion of patients surviving following cardiac arrest will be planned.