Effects of Lateral Decubitus Head-up Position, Supine Head-up Position, and Standard Lateral Decubitus Position on Hypoxemia During Recovery in Patients Undergoing Painless Gastroscopy and Colonoscopy: A Multicenter, Three-arm Randomized Controlled Trial

Painless gastroscopy and colonoscopy have become the gold standard for screening and diagnosing gastrointestinal diseases due to their high patient comfort and excellent compliance rates, with their clinical application expanding annually. This procedure is performed under intravenous general anesthesia to achieve painlessness; however, anesthetic agents exert inhibitory effects on the patient's respiratory center. Additionally, the procedural manipulation causes irritation to the airways and gastrointestinal tract, leading to a high incidence of hypoxemia during the postoperative recovery phase-the most common respiratory adverse event associated with painless gastroscopy and colonoscopy. Mild cases may prolong patient recovery time, while severe cases can result in serious complications such as hypoxic brain injury or cardiac arrest, directly compromising patient safety and healthcare experience.

Positioning is a critical non-pharmacological intervention factor influencing perioperative respiratory function in patients undergoing painless gastroscopy and colonoscopy. Different positions alter thoracic compliance, airway patency, and diaphragmatic position, thereby affecting the patient's ventilation and oxygenation status. Currently, the standard lateral decubitus position is routinely used for painless gastroscopy and colonoscopy, and it has been demonstrated to reduce the incidence of hypoxemia. However, this position presents challenges such as difficulties in patient monitoring and localized pressure-related discomfort. In contrast, the supine head-up and lateral decubitus head-up positions, by elevating the head and adjusting the body angle, effectively mitigate tongue base prolapse and improve thoracic expansion, theoretically reducing the risk of hypoxemia. Nevertheless, there is currently a lack of multicenter, large-sample, prospective randomized controlled studies to compare the efficacy and safety of these three positions in preventing hypoxemia in recovery rooms for painless gastroscopy and colonoscopy patients. Consequently, there is no unified evidence-based guideline for selecting the optimal clinical positioning.

Based on this, this study focuses on three clinically common positions and employs a multicenter, three-arm, randomized controlled parallel design to systematically investigate the effects of lateral supine with head elevated, supine with head elevated, and standard lateral position on postoperative hypoxemia in patients undergoing painless gastroscopy and colonoscopy. The aim is to fill a research gap in this field and provide high-quality evidence-based medical data to optimize postoperative position management during recovery and reduce adverse respiratory events following painless gastrointestinal endoscopy.

Special Note：Prespecified subgroup analyses will be conducted based on age (<65 vs ≥65), sex, BMI, ASA class, smoking and alcohol use, Mallampati score, anesthetic agent (clobupol or propofol), type of endoscopy (gastroscopy, colonoscopy, or gastroenteroscopy), Ramsay sedation score (2-4), pre-procedure hypoxemia, prior pulmonary surgery, OSA, respiratory disease, and intra-procedural hypoxemia (SpO₂ ≤90% for >10 seconds). The influence of heterogeneity on the primary outcome will also be evaluated.