Preventing oxygen desaturation during bronchoscopy in COPD patients using high-flow oxygen versus standard management: the randomised controlled PROSA 2 trial

Background Patients with COPD are at increased risk for developing additional respiratory comorbidities associated with smoking, and are thus prone to undergo flexible bronchoscopy. However, COPD patients have increased periprocedural complications risk and lower oxygen saturation during bronchoscopy. Methods This was an investigator-initiated, single-centre, open-label randomised controlled trial designed to assess the benefits of high-flow nasal oxygen compared to conventional low-flow oxygen by nasal cannula during conscious sedation for bronchoscopy in patients with COPD. Low flow was supplied at a starting rate of 4 L·min⁻¹ and gradually increased up to 12 L·min⁻¹ to maintain peripheral oxygen saturation (S_pO2) >90%. High flow delivered starting at a rate of 60 L·min⁻¹ and an inspiratory oxygen fraction of 0.6 was increased up to 80 L·min⁻¹ to preserve S_pO2 >90%. The primary end-point was cumulative hypoxaemia time. Results We randomised 600 COPD cases with a median (interquartile range (IQR)) age of 69.0 (62.0–76.0) years to either high flow (n=295) or low flow (n=305). The cumulative hypoxaemia time was 53% lower in the high-flow group (1.8% (95% CI 1.5–2.2%) versus 3.8% (95% CI 3.2–4.5%) of monitoring time; p<0.001). Additionally, the high-flow group experienced a median (IQR) of 3.0 (1.0–6.0) hypoxaemia events (S_pO2 <90%) compared to 6.0 (3.0–10.0) in the low-flow group (p<0.001). The low-flow group had five-fold higher odds of experiencing hypoxaemia during bronchoscopy, (OR 5.1, 95% CI 3.2–8.2; p<0.001). Conclusion High flow is feasible, decreases cumulative hypoxaemia time and reduces hypoxaemia events during bronchoscopy in patients with COPD but does not impact patient comfort.