End-tidal carbon dioxide (ETCO2) monitoring during cardiopulmonary resuscitation (CPR) provides a non-invasive estimate of alveolar carbon dioxide concentration at the end of exhalation. The key factor influencing the ETCO2 value during CPR is pulmonary blood flow, which is directly related to cardiac output generated by chest compressions. Ineffective chest compressions will result in reduced pulmonary blood flow, leading to a lower ETCO2 reading, while improved chest compressions will increase pulmonary blood flow and subsequently raise the ETCO2 value.
Consistent monitoring of ETCO2 during CPR allows for real-time assessment of the effectiveness of chest compressions and ventilation. Historically, clinicians relied on pulse checks to evaluate CPR effectiveness, but ETCO2 monitoring provides a more continuous and reliable indicator. Monitoring ETCO2 helps guide adjustments in chest compression technique, rate, and depth to optimize cardiac output and improve patient outcomes. An increasing ETCO2 reading during CPR suggests improved perfusion and a potentially higher likelihood of return of spontaneous circulation (ROSC).
