Written by Gabby Leonard
A rising ETCO2 in the setting of out-of-hospital cardiac arrest (OHCA) due to PEA has a higher chance of achieving return of spontaneous circulation (ROSC). If the change in ETCO2 is >20 mmHg during resuscitation, CPR efforts should be continued.
Why does this matter?
Non-traumatic PEA arrest in the out of hospital setting typically has poor survival rates. Our EMS colleagues have two available tools to measure cardiac activity and resuscitation efforts – EKG and ETCO2. How helpful is ETCO2 in guiding a PEA resuscitation?
This study evaluated the association between change in ETCO2 and ROSC in patients with non-traumatic PEA OHCA. Delta ETCO2 was defined as initial ETCO2 1 minute after placement of advanced airway, and final ETCO2 was recorded 1 minute prior to ROSC or at termination of resuscitation. A total of 208 patients were included, 32% of which obtained ROSC. A positive linear relationship was found between change in ETCO2 and ROSC. Specifically, odds ratio per 10 mmHg increase in ETCO2 was 1.74 (95% CI, p <0.001). Additionally, delta ETCO2 > 20 mmHg had 95% specificity for future ROSC.
This is consistent with prior studies. Paiva et al showed an ETCO2 > 20 mmHg at time of intubation or 20 minutes after ACLS initiation was the best predictor of ROSC, while ETCO2 <10 mmHg 20 minutes after ACLS initiation had 100% sensitivity and specificity for non-survival. Similarly, this study by Lui et al showed that a rapid increase in ETCO2 > 10 mmHg was specific for ROSC.
The study is limited by use of ROSC as the primary outcome. A more important question is how the change in ETCO2 during resuscitation impacts overall survival with a good neurological outcome.
The Association Between End-Tidal CO2 and Return of Spontaneous Circulation After Out-of-Hospital Cardiac Arrest with Pulseless Electrical Activity. Resuscitation. 2021 Aug 17;S0300-9572(21)00313-0. doi: 10.1016/j.resuscitation.2021.08.014. Online ahead of print.