Abstract 277: Characterizing the Components of Impulsiveness for Manual Chest Compressions During Out-of-Hospital Cardiac Arrest

Abstract

Introduction: Current resuscitation guidelines recommend depth, rate and complete recoil of chest compressions (CCs) to be monitored as part of CPR quality metrics. The literature also suggests CC impulsiveness as an additional measure of CPR quality. The impulsiveness of CCs has mainly been examined through reduced compression duration, but this fails to incorporate information of the waveform, especially for manual CCs. Aim: To retrospectively characterize impulsiveness and its components within manual CC series defined between pauses. Methods: Monitor-defibrillator recordings of adult out-of-hospital cardiac arrest cases, attended by TVF&R (OR, USA), containing depth signal, were processed to identify series of CCs between pauses. We calculated the compression impulsiveness index (see figure), CII = IF/DR, of each CC. IF is the impulse factor of the waveform, defined as its maximum depth divided by its mean depth; DR is the duration ratio, defined as the ratio between the duration of the compressive part and the total duration of the compression. We obtained variations of CII, IF and DR within series between pauses for sets of 10 consecutive CCs. Results: A total of 6,073 series of median (IQR) length 190 (119-222) CCs were used. Overall, CII was 5.27 (4.80-5.86), IF 2.19 (2.05-2.36) and DR 0.42 (0.38-0.45). From the beginning to the end of the series, median CII, DR and IF decreased 2.01%, 1.53% and 3.41%, respectively; all p trend < 0.05. This reflects that CCs change from being spikier to more rounded and shallower (see figure). Conclusion: Impulsiveness decreases moderately within CC series, which indicates that rescuers are able to maintain it during each series. The drop in IF is mainly responsible for the loss of impulsiveness, despite the decrease in DR (since IF declines twice as much). Thus, impulsiveness is better characterized by the CC waveform than by its duration. The observed overall variability of all metrics reveals differences between rescuers.