End-tidal CO2 monitoring in the OR serves what purpose?

• A. It measures only oxygen saturation.
• B. End-tidal CO2 monitoring reflects ventilation status and indicates changes requiring action.
• C. It is not used in the OR.
• D. It is only used after surgery.

Answer: (B)

End-tidal CO2 monitoring, or capnography, provides a continuous readout of ventilation by measuring the CO2 level at the end of expiration. In the operating room, this is vital because it gives immediate feedback on how well the patient is being ventilated and can signal changes that demand prompt action. A rising ETCO2 can indicate hypoventilation, airway obstruction, rebreathing, or increased CO2 production, while a falling ETCO2 can point to hyperventilation, a circuit leak or disconnection, or reduced CO2 delivery. It also helps confirm that an endotracheal tube is properly placed, since a stable, normal CO2 waveform is expected when the tube is in the airway and a sudden drop suggests displacement or loss of airway access. Oxygen saturation reflects oxygenation, not ventilation, so ETCO2 monitoring provides unique, timely information about ventilation status throughout anesthesia, not just after surgery.