Comparison of Hypoxia Between HFNC and SNC in Patient Undergoing UGI Endoscopic Procedures in Deep Sedation

This study was prospective, comparative, open-label and observational study conducted on tertiary hospital of Nepal between July 2023-April 2024.A written informed consent was taken from all the patients before enrolling to study. Patient aged more than 16 years, ASA-PS grading I-IV, both the gender, both elective procedures undergoing complex UGI endoscopic procedure in deep sedation under propofol infusion were included. Patient not willing to enrolled, pre-operative SPO2 < 92% and pre-operative MAP < 60 mm Hg were excluded from study. Sixty-two patients were enrolled in each group so total sample size was 124 using following sample size formula. .

After arriving in the procedure room, standard monitoring, including pulse oximetry, non-invasive blood pressure monitoring, and electrocardiography were attached. An anesthesiologist assigned made the decision on which oxygenation device to use for the patient. In SNC group, an oxygen flow rate of 6 l/min where in HFNC group at the beginning of procedure flow was set 10 l/min once patient was induced flow rate increased to 30 l/min with FiO2 of 0.5. The patients were positioned either laterally or semiprone. Prior to the start of the procedure, the patient was given an injection of fentanyl 1mcg/kg. An initial dose of propofol was administered at a rate of 1-1.5 mg/kg by slow titrating manner. The sedation level, ventilatory pattern,rate and depth were clinically monitored throughout the procedure.The propofol infusion was kept between 25-150 mcg/kg/min, aiming for preventing facial grimace, agitation, or gag reflex, while still allowing the patient to respond to painful stimuli. In case of any sings of agitation noticed, the anaesthesiologist added the additional dose of propofol or increase the propofol infusion rate or both, as in our usual practice.

In SNC group, if SpO2 decreased below 92%, flow rate increased to 8 l/min whereas in HFNC group FiO2 increased to 1 and flow rate increased to 50 l/min. If desaturation continued despite of above mentioned measure in both groups, anesthesiologist increased the FiO2, flow or both. Bag mask ventilation and tracheal intubation was done if needed. Other events; bradycardia needing atropine, hypotension needing vasopressor, persistent hypoxia needing bag and mask, endotracheal intubation was recorded.

Hypoxia is defined as a decrease in oxygen saturation < 92%. Severe hypoxia is defined as a decrease in oxygen saturation < 80%. Primary outcome was the compare the rate of hypoxia and secondary outcome was to compare the rate of interruption of procedure due to hypoxia and episodes of hypoxia during the procedure between the two groups.