What is required for every patient in cardiac arrest?

• A. Capnography
• B. ECG only
• C. Pulse oximetry
• D. Arterial blood gas analysis

Answer: (A)

The key idea is that CPR feedback on perfusion is essential. Capnography measures end-tidal CO2, which directly reflects pulmonary blood flow and, by extension, how effectively the heart is delivering blood to the lungs during chest compressions. Real-time EtCO2 trends are a powerful indicator: stable or rising values suggest good compressions and perfusion, while a sudden increase can signal return of spontaneous circulation. This makes capnography a standard, practical monitor to use in every cardiac arrest patient, guiding ventilation and compression quality and helping detect ROSC.

ECG is crucial for rhythm assessment and deciding shocks, but it doesn’t tell you how well blood is circulating. Pulse oximetry can be unreliable during CPR due to poor peripheral perfusion, and arterial blood gas analysis isn’t actionable during the arrest itself because results take time.