From the Guidelines
ETCO2 can be used to predict the likelihood of return of spontaneous circulation (ROSC) and survival to discharge, with values of 10 mm Hg or greater measured after tracheal intubation or after 20 minutes of resuscitation being potentially predictive of these outcomes. According to the 2020 international consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations 1, ETCO2 levels can serve as a predictor of ROSC and survival to discharge. The guidelines suggest that an ETCO2 of 10 mm Hg or greater measured after tracheal intubation or after 20 minutes of resuscitation may be a predictor of ROSC (weak recommendation, low-quality evidence) and that an ETCO2 of 10 mm Hg or greater measured after tracheal intubation, or an ETCO2 of 20 mm Hg or greater measured after 20 minutes of resuscitation, may be a predictor of survival to discharge (weak recommendation, moderate-quality evidence) 1.
Some key points to consider when using ETCO2 for predictive purposes include:
- ETCO2 values should not be used alone as a mortality predictor or for the decision to stop a resuscitation attempt (strong recommendation, low-quality evidence) 1
- ETCO2 levels can provide valuable information about the adequacy of ventilation and perfusion in patients
- The predictive value of ETCO2 is based on its relationship to ventilation, perfusion, and metabolism, which determine CO2 production and elimination in the body.
It is essential to interpret ETCO2 values in the context of the individual patient's clinical scenario, taking into account factors such as the quality of CPR, the presence of underlying medical conditions, and the patient's overall physiological state 1.
From the Research
EtCO2 Predictive Capabilities
EtCO2 can be used for predicting several outcomes, including:
- Return of spontaneous circulation (ROSC) 2, 3, 4, 5, 6
- Survival 2, 3, 5
- Efficacy of cardiac compression 2
- Coronary perfusion pressure 2
- Cardiac output 2
Predictive Factors
Several studies have identified predictive factors for ROSC and survival based on EtCO2 levels, including:
- Initial EtCO2 values ≥10mmHg 3
- Initial EtCO2 values >20mmHg 4, 5
- Initial EtCO2 values >45mmHg 5
- Delta EtCO2 (change in EtCO2 during resuscitation) 6
- EtCO2 levels <10mmHg after 20min of CPR 3
Diagnostic Characteristics
EtCO2 has been compared to other diagnostic tools, such as cerebral oximetry, and has been found to have similar diagnostic characteristics 4. EtCO2 is more sensitive, while cerebral oximetry is more specific at predicting ROSC 4.