Preoxygenation With and Without Positive End-Expiratory Pressure in Lung-Healthy Volunteers: A Randomized Clinical Trial.

Importance: Optimal preoxygenation is critical in emergency medicine to prevent desaturation during airway management, especially in high-risk populations. Identifying the most effective preoxygenation device across diverse patient groups remains a clinical priority. Objective: To compare the efficacy of 3 preoxygenation devices-nonrebreather mask (NRM), bag-valve mask (BVM), and BVM with positive end-expiratory pressure (BVM plus PEEP)-in lung-healthy volunteers. Design, Setting, and Participants: This crossover randomized clinical trial was conducted from May 26 to 31, 2024, at Eurac Research, Bolzano, Italy. Volunteer participants included lung-healthy adults with normal weight (NM), adults with overweight or obesity (OW-OB), and children aged 6 to 12 years. Exposures: Preoxygenation using each device (NRM, BVM, BVM plus PEEP) with 15 L/min of oxygen for a duration of 3 minutes in a randomized order. Main Outcomes and Measures: The primary outcome was expiratory oxygen concentration (Feo2) at the end of preoxygenation. Secondary outcomes included ventilation in dependent lung regions assessed using electrical impedance tomography, noninvasive continuous monitoring of oxygenation status (oxygenation reserve index [ORI]) at the end of preoxygenation, and the time taken for ORI to return to baseline values. Results: The study included 53 participants, 39 male (74%) and 14 female (26%), of whom 16 were adults with NW (mean [SD] age, 36 [11] years), 18 were adults with OW-OB (mean [SD] age, 45 [11] years), and 19 were children (mean [SD] age, 8 [3] years). Mean (SD) Feo2 at the end of preoxygenation was higher with BVM and BVM plus PEEP compared with NRM in adults with NW (72.1% [5.9%] and 75.6% [4.3%], respectively, vs 52.5% [6.1%]; P < .001), adults with OW-OB (65.8% [10.4%] and 73.0% [6.4%], respectively, vs 51.9% [6.1%]; P < .001), and children (64.6% [13.4%] and 67.5% [10.2%], respectively, vs 38.5% [7.5%]; P < .001). Ventilation in dependent lung regions was higher with BVM plus PEEP than NRM in adults with NW (BVM plus PEEP, 51.9 [9.3] vs NRM, 47.0 [5.7]; P = .03) and children (BVM plus PEEP, 53.0 [7.3] vs NRM, 47.7 [7.0]; P = .002). ORI at the end of preoxygenation was higher with BVM plus PEEP than with NRM in adults with OW-OB (BVM plus PEEP, 0.79 [0.13] vs NRM, 0.73 [0.13]; P < .001). Additionally, the mean (SE) time for ORI to return to baseline was longer with BVM plus PEEP compared with NRM in both adults with OW-OB (BVM plus PEEP, 196 [74] seconds vs NRM, 158 [53] seconds; P = .01) and children (BVM plus PEEP, 115 [59] seconds vs NRM, 62 [36] seconds; P < .001). Conclusions and Relevance: In this crossover randomized clinical trial, preoxygenation with PEEP was more effective than preoxygenation without PEEP, resulting in higher Feo2 values and improved ventilation in dependent lung regions. These findings suggest that BVM plus PEEP should be prioritized for preoxygenation in emergency settings. Trial Registration: ClinicalTrials.gov Identifier: NCT06370689.