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

Abstract

IntroductionThe 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. MethodsData 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 5min of chest compressions, and if no other anomaly in device use was noted. Trauma cases were excluded. ResultsNinety-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 >185mm was 53 (50–55)mm, corresponding with 19–28% of the chest diameter. The mean force required to achieve the compression depth of 53mm ranged between 219 and 568N. No correlation was found between chest height and force to reach 53mm depth (females: R2=0.001, males: R2=0.007). ConclusionThere was a large variation of the required force to achieve a compression depth of 53mm. No correlation was seen between chest height and maximum force required to compress the chest 53mm.