Abstract

Objective: Mechanical compression devices purportedly improve the quality of chest compressions by minimizing interruptions and maintaining optimal rate and depth, but this claim has not been objectively substantiated using transthoracic impedance (TTI) recordings from applied setting cardiac arrests. In this study, we use TTI data to compare chest compression quality metrics from the manual versus mechanical compression phases of out-of-hospital cardiac arrests (OHCA) treated with the LUCAS™ mechanical compression device. Methods: A retrospective analysis was conducted among all LUCAS™-aided OHCA worked by a single ambulance service in Minnesota in 2013. Events were excluded from analysis if the TTI recording was unavailable or of inadequate quality, or if duration of recorded compressions was < 5 minutes. Two paramedics independently annotated and reviewed TTI tracings using CodeStat™ software, isolated the manual and mechanical compression phases of the arrest, and recorded total CPR time, compression rate (per min) and compression fraction for each distinct phase. The main pause for LUCAS™ application was not included in either phase. Time of first mechanical compression and duration of main pause for compression device application were also determined. Results: A total of 202 events met inclusion criteria. The median (range) duration of the manual and mechanical phases were 3:13 min (0:05-19:51) and 23:24 min (0:13-65:30), respectively. Median compression fraction was lower during manual versus mechanical compressions (77% vs. 89%; p < 0.001). Median compression rates were 121/min during manual compressions and 102/min with the mechanical device (p < 0.001). On average, device placement occurred approximately 4 minutes after the start of TTI recording, with a median application pause of 26 sec (IQR = 17-44). Conclusion: These data demonstrate that use of a mechanical chest compression device can improve compression fraction and increase compliance with compression rate guidelines, but further study is needed to determine whether the observed improvement in compression quality after device placement is solely related to the mode of compression. Based on these findings, our system will emphasize earlier device placement with minimal pauses for application.

Authors and Affiliations