Comparison of a simplified nasal continuous positive airways pressure device with nasal cannula in obese patients undergoing colonoscopy during deep sedation

BACKGROUND Continuous positive airways pressure (CPAP) with a CPAP machine and mask has been shown to be more effective at minimising hypoxaemia than other devices under deep sedation. However, the efficacy of a new and simple CPAP device for spontaneously breathing obese patients during colonoscopy is unknown. OBJECTIVE We hypothesised that oxygenation and ventilation in obese patients under deep sedation during colonoscopy using CPAP via a new nasal mask (SuperNO2VA) would be better than routine care with oxygen supplementation via a nasal cannula. DESIGN Randomised study. SETTING Single-centre, June 2017 to October 2017. PATIENTS A total of 174 patients were enrolled and randomly assigned to Mask group or Control group. Thirty-eight patients were excluded and data from 136 patients underwent final analysis. INTERVENTION Patients in the Mask group were provided with nasal CPAP (10 cmH2O) at an oxygen flow rate of 15 l min−1. In the Control group, patients were given oxygen via a nasal cannula at a flow rate of 5 l min−1. MAIN OUTCOME MEASURES The primary outcome was elapsed time from anaesthesia induction to the first airway intervention. RESULTS The elapsed time from anaesthesia induction to the first airway intervention was 19 ± 10 min in the Mask group (n=63) vs. 10 ± 12 min in the Control group (n=73, P < 0.001). In all, 87.5% (56/64) of patients achieved the target CPAP value. More patients in the Control group (63%) received airway intervention than in the Mask group (22%) (P < 0.001). Hypoxaemia (pulse oximeter oxygen saturation, SpO2 < 90%) occurred more frequently in the Control group (22%) than in the Mask group (5%) (P = 0.004). Minute ventilationPostinduction/minute ventilationBaseline and minute ventilationProcedure-end/minute ventilationBaseline was lower in the Control group than in the Mask group (P = 0.007 and 0.001, respectively). CONCLUSION Application of a nasal mask at a target CPAP of 10 cmH2O improves ventilation and decreases the frequency and severity of hypoxaemia. TRIAL REGISTRATION NCT03139448, registered at ClinicalTrials.gov.