Capnography can serve as an indicator of:

• A. Chest compression effectiveness
• B. Blood glucose
• C. Temperature
• D. Oxygen content

Answer: (A)

Capnography tracks end-tidal CO2, which provides a real-time readout of how well chest compressions are moving blood to the lungs during CPR. When compressions are effective, more blood is circulated to the lungs, bringing CO2 to the alveoli to be exhaled, so the end-tidal CO2 rises. If compressions are weak or shallow, venous return and pulmonary blood flow drop, and the end-tidal CO2 falls. A rising or stable higher ETCO2 during CPR, and especially a sudden rise when circulation improves or ROSC occurs, indicates better perfusion from the compressions. This measurement is about CO2 elimination and perfusion, not about blood glucose, temperature, or oxygen content, which is why capnography serves as an indicator of chest compression effectiveness rather than those other factors.