What is the role of capnography during procedural sedation?

• A. It monitors blood pressure.
• B. It measures end-tidal CO2 for ventilatory monitoring.
• C. It tracks sedation depth via EEG.
• D. It measures oxygen saturation.

Answer: (B)

Capnography provides real-time ventilation monitoring by measuring end-tidal carbon dioxide (ETCO2). During procedural sedation, respiration can depress quickly, so detecting changes in ventilation early is essential. The capnography waveform shows not only how much CO2 is being exhaled but also the pattern of breathing and airway status, allowing immediate recognition of hypoventilation, apnea, or airway obstruction. This information helps clinicians titrate sedatives, intervene promptly (e.g., airway maneuvers, assisted ventilation), and prevent hypoxic events. ETCO2 reflects alveolar ventilation and is usually around 35–45 mmHg in healthy adults, with ETCO2 typically a bit lower than arterial CO2 due to dead space. It differs from monitoring blood pressure (hemodynamics) or EEG-based assessments of sedation depth, and it provides ventilation status beyond what pulse oximetry alone can show, since oxygen saturation can remain normal even as ventilation worsens when supplemental oxygen is used.