THRIVE in Sedated Gastrointestinal Endoscopy

Procedural sedation for gastrointestinal endoscopy is associated with risks of respiratory depression, airway obstruction, and hypoxemia due to the pharmacological effects of sedative agents. Standard nasal cannula (SNC) oxygen supplementation, while widely used, is limited in its ability to guarantee adequate inspired oxygen concentrations, particularly during apneic episodes.

THRIVE (Transnasal Humidified Rapid-Insufflation Ventilatory Exchange) delivers heated and humidified oxygen at flow rates up to 70 L/min via a non-invasive nasal cannula. The high-flow system generates positive nasopharyngeal pressure, reduces anatomical dead space through a washout effect, increases end-expiratory lung volume, and extends safe apnea time by delaying arterial desaturation. These physiological mechanisms may offer significant advantages over standard low-flow oxygen delivery during sedated endoscopy.

In this single-center prospective observational study, adult patients (age ≥18, ASA I-III, BMI <35 kg/m²) undergoing elective diagnostic gastroscopy under propofol sedation were monitored with continuous SpO₂, ETCO₂, BIS, and non-invasive Oxygen Reserve Index (ORi) monitoring. Supplemental oxygen was provided either via THRIVE at 30 L/min or standard nasal cannula at 10 L/min, based on the attending anesthesiologist's preference. Preoxygenation was initiated 2 minutes before induction and continued until procedure completion. Sedation was maintained with propofol 1-1.5 mg/kg targeting BIS 60-80; fentanyl 0.5-1 mcg/kg was administered when required. Hemodynamic and respiratory parameters were recorded at baseline, pre-induction, post-induction, intraoperatively, and at procedure end. Airway interventions were standardized and applied when apnea lasted ≥20 seconds or SpO₂ dropped ≤93% for ≥20 seconds.

Inclusion criteria

• Age ≥18 years
• ASA physical status I-III
• Body mass index (BMI) <35 kg/m²
• Scheduled for elective diagnostic gastroscopy under propofol sedation
• Baseline SpO₂ >93% on room air prior to the procedure
• Hemoglobin level ≥10.0 g/dL prior to the procedure
• Willing and able to provide written informed consent

Exclusion criteria

• Severe chronic pulmonary disease (e.g., COPD, interstitial lung disease)
• Severe chronic cardiac disease
• BMI ≥35 kg/m²
• Pregnancy
• History of facial or oropharyngeal surgery
• Baseline SpO₂ ≤93% on room air prior to the procedure
• Hemoglobinopathy
• Hemoglobin level <10.0 g/dL prior to the procedure