High-flow versus standard nasal cannula in morbidly obese patients during colonoscopy: A prospective, randomized clinical trial.

STUDY OBJECTIVE

Morbid obesity is associated with adverse airway events including desaturation during deep sedation. Prior works have suggested that proprietary high-flow nasal cannula devices generate positive pressure to all airway structures and may be superior to standard (low-flow) nasal cannula for prevention of desaturation. We hypothesized that, at a similar fraction of inspired oxygen (FiO), use of a High-Flow Nasal Cannula (HFNC) at maximum flow rate would result in a lower incidence of intra-procedural desaturation episodes in morbidly obese patients compared to standard nasal cannula (SNC) during deep sedation with propofol.

DESIGN

This is a pragmatic, prospective, randomized clinical trial at one hospital (NCT03148262, UTSW#112016-058). Morbidly obese patients were randomized to HFNC during propofol sedation for colonoscopy. HFNC was performed using maximum flow rates of 60 liters per minute (LPM) and FiO of 0.36-0.40, whereas SNC was performed at 4LPM. The primary endpoint was incidence of arterial oxygen desaturation <90% measured by pulse oximetry. At midpoint enrollment the Data Monitoring Committee (DMC) performed a pre-planned O'Brien and Fleming futility test.

MAIN RESULTS

Patients were randomized to HFNC (n = 28) or SNC (n = 31). Interim analysis of the primary endpoint showed that the desaturation rates in the HFNC group (39.3%) and the SNC group (45.2%) were not significantly different (p = 0.79). The DMC halted the trial at that point due to futility.

CONCLUSION

At similar FiO, HFNC was not significantly different from SNC for prevention of arterial oxygen desaturation in morbidly obese patients undergoing propofol sedation for colonoscopy.