How does capnography assist in determining CPR quality?

• A. Provides heart rate data.
• B. Measures arterial oxygen tension.
• C. Provides real-time perfusion feedback; higher EtCO2 generally correlates with better perfusion and ROSC potential.
• D. Indicates blood glucose.

Answer: (C)

Capnography provides real-time feedback on perfusion during CPR. End-tidal CO2 (EtCO2) is the amount of CO2 exhaled at the end of expiration, which depends on pulmonary blood flow achieved by chest compressions. When compressions generate better forward blood flow, more CO2 reaches the lungs and EtCO2 rises. Therefore a higher EtCO2 generally indicates better perfusion and a greater potential for return of spontaneous circulation. If EtCO2 stays low, it suggests poor chest compression quality or low cardiac output, prompting adjustments to the CPR technique. A sudden, sustained rise in EtCO2 can also signal ROSC. Capnography thus offers a dynamic measure of CPR quality by tracking perfusion, rather than heart rate, arterial oxygen tension, or glucose.