Chest compliance is altered by static compression and decompression as revealed by changes in anteroposterior chest height during CPR using the ResQPUMP in a human cadaver model

Chest compliance plays a fundamental role in the generation of circulation during cardiopulmonary resuscitation (CPR). To study potential changes in chest compliance over time, anterior posterior (AP) chest height measurements were performed on newly deceased (never frozen) human cadavers during CPR before and after 5min of automated CPR. We tested the hypothesis that after 5min of CPR chest compliance would be significantly increased. Static compression (30, 40, and 50kg) and decompression forces (−10, −15kg) were applied with a manual ACD-CPR device (ResQPUMP, ZOLL) before and after 5min of automated CPR. Lateral chest x-rays were obtained with multiple reference markers to assess changes in AP distance. In 9 cadavers, changes (mean±SD) in the AP distance (cm) during the applied forces were 2.1±1.2 for a compression force of 30kg, 2.9±1.3 for 40kg, 4.3±1.0 for 50kg, 1.0±0.8 for a decompression force of −10kg and 1.8±0.6 for −15kg. After 5min of automated CPR, AP excursion distances were significantly greater (p