Chest compression quality decreases in hypoxic conditions simulating an airliner cabin at cruising altitude: a randomized, controlled, double-blind Manikin Study

Abstract

Air traveler numbers are predicted to reach 4.0 billion in 2024. Between 1/15,000-50,000 passengers will experience acute medical problems inflight with cardiac arrests requiring cardiopulmonary resuscitation (CPR) accounting for 0.3% of medical emergencies. Hypoxia in airplane cabins could impair oxygenation and physical performance of caregivers. We conducted a randomized controlled, double-blind study to test the hypothesis that hypoxia decreases the effectiveness in performing CPR. We randomized 24 healthcare professionals to two different study arms, each consisting of two conditions: arm (1) 'hypoxia (FiO2 15%, equivalent to 2400 m altitude)' versus 'normoxia'; arm (2) 'hypoxia + supplemental oxygen' versus 'normoxia + supplemental oxygen'. The order of conditions was counterbalanced and a minimum wash-out period of 24 h was granted between conditions. In each condition participants performed a 5-min cardiac compression only CPR (CCO-CPR) using a full-body manikin after one, three and six hours in an altitude chamber. Mixed ANOVAs with post-hoc false-discovery-rate adjusted pairwise comparisons indicated that although compression frequency was maintained, the number of compressions with correct depth was decreased at all times during hypoxia compared to normoxia (all p < 0.002). After 6 h hypoxia exposure, mean compression depth was below the recommended compression depth defined by ERC/AHA guidelines and reduced compared to normoxia (42.4 ± 12.6 mm vs. 54.6 ± 4.3 mm, p < 0.0001). Supplemental oxygen during CCO-CPR in hypoxia prevented the decrease of compression-depth (55.3 ± 3 mm). Extended hypoxia exposure akin to conditions in airplane cabins can reduce quality of chest compressions during CPR. Supplemental oxygen for healthcare providers is an effective countermeasure.