Transpulmonary Pressure-Guided Lung-Protective Ventilation Improves Pulmonary Mechanics and Oxygenation Among Obese Subjects on Mechanical Ventilation

BACKGROUND: Transpulmonary pressure (P L ) is used to assess pulmonary mechanics and guide lung-protective mechanical ventilation (LPV). P L is recommended to individualize LPV settings for patients with high pleural pressures and hypoxemia. We aimed to determine whether P L -guided LPV settings, pulmonary mechanics, and oxygenation improve and differ from non-P L -guided LPV among obese patients after 24 h on mechanical ventilation. Secondary outcomes included classification of hypoxemia severity, count of ventilator-free days, ICU length of stay, and overall ICU mortality. METHODS: This is a retrospective analysis of data. Ventilator settings, pulmonary mechanics, and oxygenation were recorded on the initial day of P L measurement and 24 h later. P L -guided LPV targeted inspiratory P L < 20 cm H 2 O and expiratory P L of 0–6 cm H 2 O. Comparisons were made to repeat measurements. RESULTS: Twenty subjects (13 male) with median age of 49 y, body mass index 47.5 kg/m 2 , and SOFA score of 8 were included in our analysis. Fourteen subjects received care in a medical ICU. P L measurement occurred 16 h after initiating non-P L -guided LPV. P L -guided LPV resulted in higher median PEEP (14 vs 18 cm H 2 O, P = .009), expiratory P L (–3 vs 1 cm H 2 O, P = .02), respiratory system compliance (30.7 vs 44.6 mL/cm H 2 O, P = .001), and P aO 2 /F IO 2 (156 vs 240 mm Hg, P = .002) at 24 h. P L -guided LPV resulted in lower F IO 2 (0.53 vs 0.33, P < .001) and lower P L driving pressure (10 vs 6 cm H 2 O, P = .001). Tidal volume (420 vs 435 mL, P = .64) and inspiratory P L (7 vs 7 cm H 2 O, P = .90) were similar. Subjects had a median of 7 ventilator-free days, and median ICU length of stay was 14 d. Three of 20 subjects died within 28 d after ICU admission. CONCLUSIONS: P L -guided LPV resulted in higher PEEP, lower F IO 2 , improved pulmonary mechanics, and greater oxygenation when compared to non-P L -guided LPV settings in adult obese subjects.