CPR Guideline Chest Compression Depths May Exceed Requirements for Optimal Physiological Response

OlibhÊar McAlister1, Daniel Guldenring2, Dewar Finlay1, Raymond Bond1, Hannah Torney3, Ben McCartney3, Laura Davis3, Paul Crawford4, Adam Harvey3
1Ulster University, 2University of Ulster, 3HeartSine Technologies Ltd., 4Veterinary Anaesthesia Consultancy


Real-time feedback on chest compression (CC) quality during cardiopulmonary resuscitation (CPR) is invaluable for first responders. Feedback devices historically focused on depth, but the miniaturization of sensing technology is increasing the potential for physiological qualification of CCs. The following analyses evaluate the association between CC depth, systolic blood pressure (SBP) and end-tidal carbon dioxide (ETCO2) with their target cut-offs. A twelve-animal porcine study dataset was retrospectively analysed to assess associations between CC depth, SBP and ETCO2. Continuous signals for each variable were analysed. Manual CCs were applied to each animal, for 7 two-minute episodes, at CC depths between 10mm-55mm. A rolling 15-second analysis window was, in the presence of CCs, applied to the signal of each variable. For each analysis window, the mean peak value was calculated. A correlation analysis was applied to CC depth against SBP and ETCO2 to assess the strength of association between the signals of the respective variables. A cut-off analysis was then applied to determine the optimal CC depth to achieve a SBP of >= 100mmHg and an ETCO2 of >= 10mmHg. A total of 672 observations for CC depth, SBP and ETCO2 were available for analysis. The Pearson correlation-coefficient (95% confidence interval; p-value) between CC depth and both SBP and ETCO2 was 0.84 (0.82, 0.86; p < 0.001) and 0.75 (0.71, 0.78; p < 0.001) respectively. The optimal CC depth cut-off (sensitivity, specificity) to achieve SBP >= 100mmHg was 33.36mm (98.29%, 88.94%) and to achieve ETCO2 >= 10mmHg was 20.36mm (95.08%, 78.30%). The results of this study indicate a reasonable relationship between CC depth and physiological response. Optimal SBP and ETCO2 cut-offs were achieved significantly below guideline recommended depths of 50mm-60mm. Furthermore, the cut-off analysis suggests that there may be disparity between CC depth and the target physiological values.