Closed-loop oxygen control improves oxygen therapy in acute hypoxemic respiratory failure patients under high flow nasal oxygen: a randomized cross-over study (the HILOOP study)

We aimed to assess the efficacy of a closed-loop oxygen control in critically ill patients with moderate to severe acute hypoxemic respiratory failure (AHRF) treated with high flow nasal oxygen (HFNO). In this single-centre, single-blinded, randomized crossover study, adult patients with moderate to severe AHRF who were treated with HFNO (flow rate ≥ 40 L/min with FiO ≥ 0.30) were randomly assigned to start with a 4-h period of closed-loop oxygen control or 4-h period of manual oxygen titration, after which each patient was switched to the alternate therapy. The primary outcome was the percentage of time spent in the individualized optimal SpO range. Forty-five patients were included. Patients spent more time in the optimal SpO range with closed-loop oxygen control compared with manual titrations of oxygen (96.5 [93.5 to 98.9] % vs. 89 [77.4 to 95.9] %; p