Using prospective real-world data, this study aims to determine whether the lateral decubitus position reduces the incidence of post-procedure hypoxemia in patients undergoing painless gastroscopy/colonoscopy, thereby providing a simple, non-invasive, and low-cost optimization strategy for clinical practice.
Age ≥ 18 years.
Both sexes.
American Society of Anesthesiologists (ASA) physical status classification I-III.
Scheduled for combined painless esophagogastroduodenoscopy/colonoscopy or either of the two procedures.
Severe cardiovascular or cerebrovascular diseases.
Pregnant patients.
History of hypersensitivity to ciprofol.
Endotracheal intubation required during the procedure.
Parallel
Lateral decubitus position group (Group L)
Procedure/SurgeryUpon admission to the Post-Anesthesia Care Unit (PACU), an independent researcher (attending anesthesiologist) assessed the patient using the Ramsay Sedation Scale (1: anxious and agitated; 2: awake, calm, and cooperative; 3: drowsy but responsive to verbal commands; 4: asleep but responsive to tactile stimulation or pain; 5: asleep with a sluggish response to stimulation; 6: deep sleep with no response). Patients in the Lateral Group (Group L) were maintained in the predetermined left lateral position. Standard monitoring was applied, and nasal cannula oxygen was administered at 2 L/min. If SpO₂ remained \>95% for at least 5 minutes, oxygen was discontinued for observation. To ensure strict adherence to the protocol, an independent researcher continuously monitored and verified patient positioning (corrections were made only if the patient rolled unconsciously). Patients were evaluated using the Aldrete discharge scoring system; discharge from the PACU occurred when a score of \>9 was a
Supine position group (Group S)
Procedure/SurgeryUpon admission to the Post-Anesthesia Care Unit (PACU), an independent researcher (attending anesthesiologist) assessed the patient using the Ramsay Sedation Scale (1: anxious and agitated; 2: awake, calm, and cooperative; 3: drowsy but responsive to verbal commands; 4: asleep but responsive to tactile stimulation or pain; 5: asleep with a sluggish response to stimulation; 6: deep sleep with no response). Patients in the Supine Group (Group S) were turned from the predetermined lateral position to the supine position without a head pillow (head-of-bed elevation at 0 degrees). Standard monitoring was applied, and nasal cannula oxygen was administered at 2 L/min. If SpO₂ remained \>95% for at least 5 minutes, oxygen was discontinued for observation. To ensure strict adherence to the protocol, an independent researcher continuously monitored and verified patient positioning (corrections were made only if the patient rolled unconsciously). Patients were evaluated using the Aldrete discharge
Incidence of recovery-phase hypoxemia,
Proportion of participants experiencing hypoxemia (SpO₂ ≤ 90% lasting \>10 seconds) during the post-procedure recovery period.
Incidence of Severe Hypoxemia During Recovery
Proportion of participants experiencing severe hypoxemia, defined as pulse oxygen saturation (SpO₂) \< 85% lasting \>10 seconds during the post-procedure recovery period.
Incidence of Subclinical Respiratory Depression during Recovery
Proportion of participants experiencing subclinical respiratory depression, defined as any episode of pulse oxygen saturation (SpO₂) in the range of 90% to \<95% (inclusive of 90%, exclusive of 95%) during the post-procedure recovery period.
Overall Incidence of Airway Intervention During Recovery
Proportion of participants requiring any grade of airway intervention (increase oxygen flow, chin lift, mask ventilation, or reintubation) during recovery.
Cough Severity Grade During Recovery
Severity of cough assessed during the recovery period, graded as: Grade I: No cough, smooth breathing; Grade II: Single mild cough; Grade III: Multiple coughs lasting \<15 seconds; Grade IV: Continuous coughing lasting ≥15 seconds. Reported as the proportion of participants reaching each grade (I-IV).
Prespecified Subgroup Analyses
Subgroup analyses will be conducted to explore heterogeneity of treatment effects on the primary outcome (incidence of recovery-phase hypoxemia) across baseline categories: Demographics: age (\<65 vs ≥65 years), sex, body mass index (BMI) category; Clinical characteristics: ASA physical status (I-II vs III), smoking/alcohol history, Mallampati classification (I-II vs III-IV); Procedural factors: endoscopy type (gastroscopy vs colonoscopy vs combined), preprocedural hypoxemia (room-air SpO₂ ≤90%), history of pulmonary surgery, obstructive sleep apnea (OSA), respiratory comorbidities (asthma/COPD/chronic bronchitis/emphysema/bullae), and intraprocedural hypoxemia (SpO₂ ≤90% \>10 s); Postprocedural sedation: Ramsay Sedation Score (2-6). Effect modification will be tested using interaction terms in regression models (or stratified analysis with Cochran-Mantel-Haenszel test).
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