Respiratory support with nasal high flow without supplemental oxygen in patients undergoing endoscopic retrograde cholangiopancreatography under moderate sedation: a prospective, randomized, single-center clinical trial

BACKGROUND: Nasal high flow (NHF) may reduce hypoxia and hypercapnia during an endoscopic retrograde cholangiopancreatography (ERCP) procedure under sedation. The authors tested a hypothesis that NHF with room air during ERCP may prevent intraoperative hypercapnia and hypoxemia. METHODS: In the prospective, open-label, single-center, clinical trial, 75 patients undergoing ERCP performed with moderate sedation were randomized to receive NHF with room air (40 to 60 L/min, n = 37) or low-flow O(2) via a nasal cannula (1 to 2 L/min, n = 38) during the procedure. Transcutaneous CO(2), peripheral arterial O(2) saturation, a dose of administered sedative and analgesics were measured. RESULTS: The primary outcome was the incidence of marked hypercapnia during an ERCP procedure under sedation observed in 1 patient (2.7%) in the NHF group and in 7 patients (18.4%) in the LFO group; statistical significance was found in the risk difference (-15.7%, 95% CI -29.1 – -2.4, p = 0.021) but not in the risk ratio (0.15, 95% CI 0.02 – 1.13, p = 0.066). In secondary outcome analysis, the mean time-weighted total PtcCO(2) was 47.2 mmHg in the NHF group and 48.2 mmHg in the LFO group, with no significant difference (-0.97, 95% CI -3.35 – 1.41, p = 0.421). The duration of hypercapnia did not differ markedly between the two groups either [median (range) in the NHF group: 7 (0 – 99); median (range) in the LFO group: 14.5 (0 – 206); p = 0.313] and the occurrence of hypoxemia during an ERCP procedure under sedation was observed in 3 patients (8.1%) in the NHF group and 2 patients (5.3%) in the LFO group, with no significant difference (p = 0.674). CONCLUSIONS: Respiratory support by NHF with room air did not reduce marked hypercapnia during ERCP under sedation relative to LFO. There was no significant difference in the occurrence of hypoxemia between the groups that may indicate an improvement of gas exchanges by NHF. TRIAL REGISTRATION: jRCTs072190021. The full date of first registration on jRCT: August 26, 2019.