Abstract 251: Measuring the Association of CPR Quality Metrics and Intra-Arrest End-Tidal Carbon Dioxide
Background: End-tidal carbon dioxide (ETCO2) is an indicator of blood flow during low-flow states such as during CPR delivery. Given that cardiac arrest survival is sensitive to CPR quality, ETCO2 might serve to guide CPR during clinical care. ETCO2 has been shown to be a useful indicator of CPR quality in laboratory arrest models, however, there is a lack of clinical data assessing this relationship in humans.
Objectives: To determine the association between quantitative CPR performance and intra-arrest ETCO2 in a time-based analysis of clinical resuscitation events.
Methods: In this single center retrospective study we collected ETCO2 data and time-synchronized CPR quality metrics using CPR-recording defibrillators (MRx QCPR, Philips Healthcare) during cardiac arrest events between 08/2007-06/2012. For each case, mean ETCO2 for each 30 sec segment of CPR was calculated manually by averaging the peaks of each capnographic waveform. CPR 30 sec segments were divided into tertiles based on rate and depth, and combined to form nine groups representing combinations of CPR performance. A mixed-effect regression of mean ETCO2 with the nine CPR combinations was performed using shallow depth and slow rate as the reference category.
Results: Of the 54 arrest events with both CPR quality metrics and ETCO2 waveform data, we extracted 992 30 sec blocks that had compression pauses < 5 sec. Deep compression depth coupled with a slow, medium or fast rate and a medium depth coupled with a fast rate produced statistically significant higher ETCO2 values than the reference category (see figure).
Conclusions: Greater compression rate and depth are associated with higher mean ETCO2 during the same 30 sec period of time. This relationship suggests a physiologic response to CPR quality as detected via ETCO2 measurement. The potential clinical use of ETCO2 to guide CPR requires further investigation.
- © 2013 by American Heart Association, Inc.