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

A twelve-animal porcine study dataset was retrospectively analyzed to assess associations between chest compression (CC) depth, systolic blood pressure (SBP) and end-tidal carbon dioxide (EtCO2). Manual CCs were applied for 7 two-minute episodes, at CC depths between 10mm−55mm. A rolling 15s analysis window was applied to the continuous signals. Mean peak values were calculated for each window. Correlation analysis was applied to assess strength of association. Optimal CC depth to achieve physiological targets was determined via cut-off analysis. A total of 672 observations for each variable were available for analysis. Pearson correlations (95% confidence interval; p-value) between CC depth and both SBP and ETCO2 were 0.84 $(0.82, 0.86; p < 0.001)$ and 0.75 $(0.71, 0.78; p < 0.001)$ respectively. Optimal CC depth cutoff (sensitivity, specificity) to achieve $SBP \ge 100mmHg$ and $EtCO_{2}\ge 10mmHg$ was 33 mm (98.29%, 88.94%)and 20 mm (95.08%, 78.30%) respectively. A reasonable relationship between CC depth and physiological response was observed. Optimal SBP and EtCO2 cut-offs were achieved significantly below guideline depths. Furthermore, cut-off analysis suggests a disparity between CC depth and physiological targets.