MD Department of Critical Care Medicine, Nerima Hikarigaoka Hospital, United States
Introduction: Various methods for determining optimal PEEP in ARDS have been examined, including maximizing oxygenation or respiratory system compliance, and achieving an end-expiratory transpulmonary pressure of 0 cmH2O or higher. However, none of these methods have improved mortality rates. Consequently, the optimal method for determining PEEP remains unclear and is left to individual clinician discretion.
Methods: This multicenter prospective observational study enrolled adult ARDS patients admitted to the ICU requiring mechanical ventilation with a P/F ratio of less than 200. PEEP was measured using three methods: (1) PEEP based on the ARDS Network's lower PEEP/higher FIO2 table (PEEP-low), (2) the minimum PEEP that results in an end-expiratory transpulmonary pressure of 0 cmH2O or higher using an esophageal pressure balloon (PEEP-es), and (3) PEEP determined using Electrical Impedance Tomography (EIT) to minimize overdistension and collapse (PEEP-EIT). For each method, arterial blood gas analysis was performed 10 minutes after setting to measure the P/F ratio, driving pressure (ΔP) and respiratory system compliance (Crs).
Results: From September 1, 2023, to July 31, 2024, 11 patients were enrolled. The median age was 77 years, with five males (45%), and a median BMI of 23.5. No patients had airway opening pressure recorded. PEEP was generally higher in the PEEP-es group compared to the other groups, significantly higher than that in the PEEP-EIT group (14[12-15] vs. 11[8.5-12], p=0.03) but not significantly different from the PEEP-low group (vs. 10[9-11], p=0.06). No significant differences in the P/F ratio were observed among the groups. However, ΔP significantly improved in the PEEP-EIT group compared to the PEEP-low(10[9.5-12] vs. 12[9.5-16], p=0.02) and the PEEP-es(vs. 11[10-13.5], p=0.01). Similarly, Crs significantly improved in the PEEP-EIT group compared to the PEEP-low (33.3[26.5-39.8] vs. 27.3[23.8-35.0], p=0.03)and the PEEP-es (vs. 30.8[24.6-34.7], p=0.03).
Conclusions: In ARDS patients, we examined changes in respiratory mechanics with PEEP determined by different methods. Although there was no significant difference in actual PEEP values, EIT-determined PEEP improved ΔP and Crs more than the other methods. EIT could be an effective method for determining optimal PEEP in ARDS.
