Force and depth of mechanical chest compressions and their relation to chest height and gender in an out-of-hospital setting.

Abstract

The LUCAS 2 device stores technical data that documents the chest compression process. We analyzed chest wall dimensions and mechanics stored during chest compressions on humans using data gathered with the LUCAS 2 device. Data from LUCAS 2 devices used in out-of-hospital cardiac arrest were downloaded with dedicated proprietary software and matched to the corresponding patient data. Cases were included only if the suction cup was placed correctly, if it was not realigned during the first 5 min of chest compressions, and if no other anomaly in device use was noted. Trauma cases were excluded. Ninety-five patients were included. All patients received manual cardiopulmonary resuscitation prior to the application of the device. The mean (SD) chest height was 232 (25)mm for males and 209 (26)mm for females (P < 0.001). The mean (min-max) compression depth in patients with chest height >185 mm was 53 (50-55)mm, corresponding with 19-28% of the chest diameter. The mean force required to achieve the compression depth of 53 mm ranged between 219 and 568 N. No correlation was found between chest height and force to reach 53 mm depth (females: R(2) = 0.001, males: R(2) = 0.007). There was a large variation of the required force to achieve a compression depth of 53 mm. No correlation was seen between chest height and maximum force required to compress the chest 53 mm.