Resuscitation From Out-of-Hospital Cardiac Arrest: When Is EtCO₂ Reliably Associated With ROSC?

Area of Science:

• Emergency Medicine
• Cardiology
• Critical Care

Background:

• Exhaled end-tidal carbon dioxide (EtCO2) monitoring is vital for predicting outcomes in out-of-hospital cardiac arrest (OHCA).
• The minimum duration of EtCO2 monitoring required to distinguish between return of spontaneous circulation (ROSC) and non-ROSC is not well-established.
• Understanding this duration is critical for optimizing resuscitation efforts and patient prognostication.

Purpose of the Study:

• To determine the minimum EtCO2 monitoring duration necessary to reliably differentiate ROSC from non-ROSC in OHCA patients.
• To analyze EtCO2 trajectories and their association with resuscitation outcomes.
• To identify the earliest time point at which EtCO2 trajectories can predict ROSC.

Main Methods:

• A secondary analysis of the Pragmatic Airway Resuscitation Trial (PART) was conducted.
• Group-based trajectory modeling (GBTM) was used to identify upward or downward EtCO2 trajectories.
• Inverse probability of treatment weighting was applied to balance baseline characteristics, and logistic regression models estimated risk ratios for ROSC.

Main Results:

• EtCO2 data from 1168 OHCA patients were analyzed, stratified by witnessed status and initial EtCO2 levels.
• For witnessed arrests, reliable differentiation occurred between 8 and 21 minutes, depending on initial EtCO2.
• For unwitnessed arrests, non-overlapping confidence intervals were observed at 7 minutes, indicating early prognostic value.

Conclusions:

• Monitoring duration of 7 to 21 minutes is needed to differentiate EtCO2 trajectories in OHCA resuscitation.
• Dynamic EtCO2 trajectory analysis offers early prognostic insights for guiding resuscitation strategies.
• This finding has significant implications for real-time decision-making during cardiac arrest events.