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

Introduction 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 5 min of automated CPR. We tested the hypothesis that after 5 min of CPR chest compliance would be significantly increased. Methods Static compression (30, 40, and 50 kg) and decompression forces (−10, −15 kg) were applied with a manual ACD-CPR device (ResQPUMP, ZOLL) before and after 5 min of automated CPR. Lateral chest x-rays were obtained with multiple reference markers to assess changes in AP distance. Results 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 30 kg, 2.9 ± 1.3 for 40 kg, 4.3 ± 1.0 for 50 kg, 1.0 ± 0.8 for a decompression force of −10 kg and 1.8 ± 0.6 for −15 kg. After 5 min of automated CPR, AP excursion distances were significantly greater (p < 0.05). AP distance increased to 3.7 ± 1.4 for a compression force of 30 kg, 4.9 ± 1.6 for 40 kg, 6.3 ± 1.9 for 50 kg, 2.3 ± 0.9 for −10 kg of lift and 2.7 ± 1.1 for −15 kg of lift. Conclusions These data demonstrate chest compliance increases significantly over time as demonstrated by the significant increase in the measured AP distance after 5 min of CPR. These findings suggest that adjustments in compression and decompression forces may be needed to optimize CPR over time.