A 55-year-old patient with ASA III status (well-controlled hypertension, BMI 33 kg/m²) is scheduled for colonoscopy under Monitored Anaesthesia Care (MAC). Which drug combination is MOST appropriate for deep procedural sedation while preserving spontaneous ventilation?

• A Midazolam 5 mg IV followed by haloperidol
• B Ketamine 2 mg/kg IV as sole agent
• C Thiopentone 3 mg/kg IV with nitrous oxide 70%
• D Propofol infusion (50–200 mcg/kg/min) ± low-dose fentanyl ✓

Explanation

For MAC/procedural sedation, propofol infusion (titrated 50–200 mcg/kg/min) with or without a small dose of fentanyl (25–50 mcg) is the standard of care in gastrointestinal endoscopy suites and non-operating room anaesthesia. Propofol provides rapid onset, easily titratable depth, and fast recovery. In obese patients, careful titration and supplemental oxygen are essential; capnography is recommended for monitoring ventilation. Ketamine at full anaesthetic doses (2 mg/kg) causes emergence reactions and is not appropriate as a sole agent. Midazolam has slow onset and delayed recovery unsuitable for high-throughput day-care.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.