Uses and pitfalls of measurement of end-tidal carbon dioxide during cardiac arrest

To discuss recent studies relevant to the utility of measuring end-tidal carbon dioxide (ETCO2) during cardiopulmonary resuscitation (CPR) and its correlation with outcome in adults experiencing cardiac arrest.

Over the past couple of years, at least five studies have included measurement of ETCO2 in their methods. Two of these studies were prospective and two retrospective. All considered ETCO2 measurements after out-of-hospital cardiac arrest, either in the prehospital setting, or after arrival in the emergency department. All assessed for an association between ETCO2 measurement and return of spontaneous circulation (ROSC). However, the timing of measurement, whether a one-off value or a trend and the cut-off values used to determine whether or not there was an association were different in all cases.

Higher values of ETCO2 during resuscitation from cardiac arrest are generally associated with a greater likelihood of ROSC. However, timing of measurements and cut-off values used show significant variability across different studies, making it hard to draw any conclusions about the utility of any particular reading for prognostication. Future studies might aim to develop an accepted standard for the timing and cut-off value of ETCO2 used, to enable comparison of the parameter across different studies.