During propofol-based MAC sedation for an upper GI endoscopy, the patient develops respiratory depression with a falling respiratory rate. Which monitor will detect this deterioration EARLIEST?
- A Pulse oximetry
- B Precordial stethoscope
- C Nasal capnography ✓
- D Non-invasive blood pressure
Correct answer: C. Nasal capnography
Explanation
Capnography detects hypoventilation and apnoea within seconds through expired carbon dioxide changes, whereas pulse oximetry lags because desaturation only appears after significant oxygen reserve depletion, particularly in preoxygenated or oxygen-supplemented patients. The ASA standards recommend continuous capnography for moderate to deep sedation precisely because it precedes haemoglobin desaturation. A precordial stethoscope is far less sensitive and non-invasive blood pressure does not reflect ventilation.
Reference: Morgan and Mikhail's Clinical Anesthesiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.