Abstract 18435: ETCO2 Alone is Inadequate to Verify CPR Quality
Background: Previous studies have described modest correlation between end-tidal CO2 (ETCO2) and CPR quality during resuscitation of cardiac arrest patients, but it is unclear whether ETCO2 alone can indicate CPR quality. The present study investigated whether ETCO2 adequately identifies the quality of CPR provided during out-of-hospital cardiac resuscitation.
Methods: ETCO2 was monitored with side-stream CO2 (Philips/Respironics) and CPR quality measured with an accelerometer-based system (E Series, ZOLL Medical) during the treatment of consecutive adult OHCA patients with presumed cardiac etiology by 2 EMS agencies in the Arizona SHARE QI Program between 10/08-06/13. Minute-by-minute ETCO2 and CPR quality were extracted. ETCO2 values were log transformation to achieve approximate normality. Linear mixed effect models were fitted to use (transformed) ETCO2 level to predict four CPR variables: chest compression (CC) depth, CC rate, CC release velocity (CCRV), and ventilation rate (VR). A random intercept for each case was included and a spatial power covariance structure assumed for measurements over time.
Results: 230 subjects (median age 69 yrs, 69% male) with 1581 minutes of data were studied. Transformed ETCO2 was significant for CC depth (p< 0.0001), CCRV (p=0.003) and VR (p<0.0001), but only explained 3.7%, 2.7%, and 10.0% of the total variance for these variables, respectively. Transformed ETCO2 was not a significant predictor for CC rate (p=0.89). The Figure illustrates the overlap in CC depth over quartiles of ETCO2, demonstrating that any specific ETCO2 level could be found over a wide range of CC depths.
Conclusion: In this secondary analysis, ETCO2 was not an independent indicator of CC rate but was a weak predictor for CC depth, CCRV and VR. These findings suggest that ETCO2 may be not be an adequate substitute for CPR quality monitoring. Future studies should investigate how ETCO2 and CPR quality monitoring can be used in conjunction to optimize CPR.
Author Disclosures: C. Hu: None. D. Spaite: Research Grant; Modest; Medtronic. T. Vadeboncoeur: None. C. Hypes: None. R.A. Murphy: None. A. Silver: Employment; Significant; ZOLL Medical. B. Bobrow: Research Grant; Modest; Medtronic.
- © 2015 by American Heart Association, Inc.