Lit Matters 1: How to Use EtCO2 During Resus

End-tidal CO2 during cardiac arrest is more than a tube-confirmation number; it tracks pulmonary blood flow and correlates with CPR-generated perfusion. In out-of-hospital cardiac arrest, early EtCO2 trajectory helps frame ROSC likelihood, while persistently very low values signal a poor resuscitation prognosis.

EtCO2 Trajectory in OHCA Resuscitation

• Perfusion marker during CPR: EtCO2 functions as a bedside surrogate for blood flow during chest compressions, so rising values generally mean better CPR-generated perfusion and a better chance of ROSC.
• Three trajectory patterns: This cohort separated into low, intermediate, and high EtCO2 trajectories centered around 10, 30, and 50 mmHg, with higher trajectories linked to better return of spontaneous circulation.
• Early monitoring matters: Trajectory is only useful if capnography is in place early enough to capture serial readings; that practical timing point is worth hearing in the episode.
• Low-value prognostic signal: Persistently very low EtCO2, especially an average under about 15 mmHg, should temper expectations for ROSC and can support discussion about when ongoing CPR may be futile.
• Final and minimum values: Among the measured capnography variables, minimum and final EtCO2 appeared most predictive, giving clinicians a simple way to interpret trend direction without overcomplicating the code.
• Neurologic outcome caution: Higher EtCO2 trajectories improved ROSC and the highest trajectory tracked with survival to discharge, but favorable neurologic recovery did not clearly separate across groups.