Effects of low-dose esketamine on hypoxemia during gastroscopy in patients with moderate-to-high risk obstructive sleep apnea: protocol for a prospective, randomized, controlled trial

Background Propofol sedation in patients with Obstructive Sleep Apnea (OSA) frequently induces hypoxemia, posing significant clinical risks. Esketamine, an N-Methyl-D-Aspartate (NMDA) receptor antagonist, may reduce propofol requirements while preserving respiratory stability, but its efficacy in OSA patients remains unproven. At the studied dose (0.25 mg/kg), esketamine’s potential side effects (transient hypertension) are expected to be mild and self-limited. Therefore, we aimed to test whether low-dose esketamine (0.25 mg/kg) can reduce the incidence of hypoxemia in moderate-to-high risk OSA patients during propofol-based painless gastroscopy. Methods This single-center, double-blind, randomized controlled superiority trial will enroll 294 patients (STOP-Bang score ≥ 3, 18–90 years, STOP-Bang = Snoring, Tiredness, Observed apnea, Pressure [blood], Body Mass Index [BMI], Age, Neck size, Gender.) undergoing gastroscopy. Participants will be randomized 1:1 to receive either esketamine (0.25 mg/kg) plus propofol or saline placebo plus propofol, stratified by age (18–65 vs. > 65 years) and OSA severity (STOP-Bang 5–6 vs. ≥ 7). The primary outcome is the incidence of hypoxemia (Peripheral Oxygen Saturation [SpO 2 ] < 90% for > 10 s). Secondary outcomes include severe hypoxemia (SpO 2 ≤ 75% or ≤ 90% for ≥ 60 s), duration of hypoxemia, emergency airway management, propofol consumption, hemodynamic stability, involuntary body movements, procedure/recovery times, and clinician satisfaction (measured via 10-cm Visual Analog Scale [VAS]). Discussion This protocol rigorously evaluates esketamine’s potential to improve sedation safety in OSA patients, addressing a critical gap in peri-procedural care. Trial registration Chinese Clinical Trial Registry (ChiCTR2500099420). Registered on March 24, 2025 (Supplementary File 2). Si-Qi Hao is a co-first author with the same contribution as the first author. The corresponding author is Li-Xin An.