Abstract 17380: End-tidal Carbon Dioxide During Resuscitation is Associated With CPR Depth and Ventilatory Rate
Introduction: End-tidal carbon dioxide (ETCO2) has been proposed as a physiologic marker of blood flow during CPR.
Hypothesis: We hypothesized that ETCO2 values would be associated with initial rhythm, witnessed status, impedance threshold device (ITD) use, CPR quality measures and ventilatory rates (VR).
Methods: Chest compression (CC) metrics, VR, and ETCO2 values from prehospital resuscitation attempts were averaged over each 1 min of resuscitation. When return of spontaneous circulation (ROSC) was identified, as evidenced by the cessation of CC and measurement of a blood pressure, we censored 1 min prior to the termination of CC to reduce the measurement of unrecognized ROSC physiology. Mixed effects models were used for analysis.
Results: Monitor data from N=102 adult prehospital resuscitation attempts was available for analysis, providing 1,079 (1-min) epochs for analysis (median of 8 min/case, IQR 4-14). ETCO2 appeared at a median of 9 min (IQR 6-12) into resuscitation, measured from an endotracheal tube (78%), laryngeal tube (21%), and bag valve mask (1%). Median VR was 9 breaths/min (IQR 6-11). Average initial ETCO2 was 28 (95% CI 25-31) followed by an average rise of 0.8 mm Hg/min (95% CI 0.5-1.1), regardless of ITD use, initial rhythm, or witnessed status. In univariate analysis, ETCO2 was not associated with CC fraction, rate, or release velocity but was associated with CC depth (2.7 mm Hg/inch of depth, 95% CI 0.1-5.4), and VR (quadratic response, p<0.0001). Results held in multivariate analysis. In the narrow range of low VRs observed in our sample, increased VRs were associated with higher ETCO2 values between 0-17 breaths/min before falling at higher rates (FIGURE).
Conclusions: Similar to others, we observed a linear association between ETCO2 and CC depth but a quadratic relationship between ETCO2 and VR during prehospital resuscitation. Improving CC depth and maintaining a VR of 10 breaths/min may optimize ETCO2 values in adults.
Author Disclosures: J. Tonna: None. C.R. Clark: None. B.R. Fogg: None. S. Youngquist: None.
- © 2015 by American Heart Association, Inc.