EFFICACY OF CHEST COMPRESSION TECHNIQUES FOR CARDIOPULMONARY RESUSCITATION (CPR) IN REDUCED GRAVITY

Introduction: The initiative to send crews to the Moon and Mars raises consideration of potential in-flight emergencies, including the need tc provide CPR. We evaluated the efficacy and implementation of two existing and two new chest compression (CC) techniques in 1-G and O-G. Methods: Efficacy of three CC techniques, delivered by three rescuers, was evaluated in three healthy volunteer subjects at 1-G. Each subject was instrumented for intraesophageal, central venous, and central arterial pressure (IEP,CVP,CAP), cerebral perfusion (transcranial Doppler velocity,TCDV), CC force (CCF), regional oxygen saturation and blood volume index (rSO2, BVI), and electrocardiogram. Rescuers delivered metered, partial CC (-70 Ibs) on every third heartbeat during systole with the subject supine using side-straddle (CMRS) CC and using a new modification with extra rescuer restraining straps to oppose 'chest compression recoil' (MCMRS). A new, third CC technique used circumferential CCs at the cardiac level (modified Heimlich maneuver or 'backward bear hug,' BBH) with the subject upright. CC efficacy was based on augmentation of IEP, CAP, TCDV, and coronary perfusion pressure (CPP = CAP - CVP) compared to beats without CC. Supplemental data were obtained from an instrumented mannequin receiving CC in 0-G during parabolic flight. The techniques previously mentioned and a fourth technique, vertical (handstand) CPR, were evaluated.