Approaches to Mechanical Ventilation in Patients With and Without Acute Brain Injury: A Registry-Based Cohort Study

Objectives: Differences in mechanical ventilation strategies between patients with and without acute brain injury (ABI) remain incompletely characterized. We aimed to compare ventilation approaches in patients with and without ABI over a 10-year period and to investigate impacts of practice changes on Pa o 2 and Pa co 2 . Design: Retrospective registry-based cohort study involving prospectively collected data from nine ICUs across Toronto, Ontario, Canada. Setting and Patients: Adult patients (≥ 18 yr) receiving invasive ventilation for at least 48 hours from 2014 to 2023 were included. Patients were classified as having ABI (exposure) or non-ABI (comparator) conditions. Between-group differences in tidal volume (V t ), positive end-expiratory pressure (PEEP), Pa co 2 , and Pa o 2 were summarized using adjusted linear mixed-effects regression. Six additional ventilation and gas exchange variables were evaluated in unadjusted analyses. Interventions: None. Measurements and Main Results: Thirteen thousand nine hundred twenty-five patients were included. Mean age ( sd ) was 59.1 years (17.5 yr), 38.1% of patients ( n = 5305) were female, and 25.2% had ABI ( n = 3503). Over the first 7 ventilation days, V t was comparable between groups, with a daily median close to 6 mL/kg (interquartile range, 6–7 mL/kg) predicted body weight. PEEP was significantly lower in patients with ABI (median 5 vs. 8 cm H 2 O in non-ABI patients; p < 0.001). Among patients with hypoxemic respiratory failure, PEEP remained significantly lower in the ABI subset. From 2014 to 2023, V t decreased slightly in both groups, while PEEP remained unchanged. Pa co 2 was largely maintained within 35–45 mm Hg in ABI patients and Pa o 2 remained largely within 80–120 mm Hg. Differences in six additional ventilation parameters between groups were minimal. Conclusions: Both ABI and non-ABI patients received comparable V t that trended downwards over time. Pa co 2 and Pa o 2 remained largely within guideline-recommended ranges. However, PEEP was significantly lower in ABI patients, including among those with hypoxemic respiratory failure, highlighting potential opportunities to improve PEEP application in relevant subsets.