Transpulmonary pressure guided optimal positive end-expiratory pressure selection in patients with acute respiratory distress syndrome / 中华危重病急救医学

ABSTRACT

Objective To evaluate the value of transpulmonary pressure (Ptp) guided optimal positive end-expiratory pressure (PEEP) selection in patients with early acute respiratory distress syndrome (ARDS).Methods A prospective randomized self-control study was conducted.ARDS patients in the early stage (onset ≤3 days) undergoing intubation and mechanical ventilation admitted to intensive care unit (ICU) of Jiangsu Provincial Subei People's Hospital from December 2013 to December 2015 were enrolled.The PEEP level was regulated to 30 cmH2O (1 cmH2O =0.098 kPa) after recruitment maneuver,and then it was gradually decreased to 0 with lowering by 3 cmH2O every 5 minutes.The optimal PEEP was titrated by Ptp,lowest dead space fraction (VD/VT),highest static lung compliance (Cst),and optimal oxygenation,respectively.Parameters of respiratory mechanics and gas exchange were observed.Results Totally 28 patients with ARDS (including 17 male and 11 female) were included with the average age of (45 ± 12) years old,acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) score was 21 ± 9,oxygenation index (PaO2/FiO2) was (165 ± 76) mmHg (1 mmHg =0.133 kPa).① During decremental PEEP titration,Ptp was gradually decreased,and expiratory Ptp (Ptp-e) was more than zero [(1.3±0.3) cmH2O] when PEEP was (9.6 ± 2.3) cmH2O.Cst was initially improved until reaching a peak,and then deteriorated.Cst was highest [(50 ± 8) mL/cmH2O] when PEEP was (11.5 ± 2.4) cmH2O.PaO2/FiO2 reached the maximum [(312 ± 99) mmHg] at PEEP level of (18.0 ± 2.5) cmH2O.Compared with Ptp-e 3.00-5.99 cmH2O,PaO2/FiO2 was significantly decreased when Ptp-e became negative (all P ＜ 0.05).VD/VT was lowest (0.52 ±0.05) when PEEP was (10.1 ± 2.2) cmH2O.When compared with ventilation [inspiratory Ptp (Ptp-i) 0-2.99 cmH2O],it was significantly higher during high (Ptp-i ≥ 15 cmH2O,all P ＜ 0.05).② There were no statistically significant differences in the levels of optimal PEEP,Ptp-i and Ptp-e among Ptp,lowest VD/VT and highest Cst methods (all P ＞ 0.05),but they were significantly less than optimal oxygenation method (all P ＜ 0.05).Compared with baseline and the method of optimal oxygenation,Cst in other three PEEP titration methods including Ptp,lowest VD/VT and highest Cst was improved obviously (mL/cmH2O46± 7,47±9,50± 8 vs.30± 8,35 ± 10,all P ＜ 0.05).PaO2/FiO2 (mmHg) in the method of Ptp and lowest VD/VT were higher than the baseline (252 ± 86,258 ± 72 vs.165 ± 76,both P ＜ 0.05),but significantly lower than that of optimal oxygenation method (312 ± 99,both P ＜ 0.05),and did not significantly differ from that of highest Cst (268± 85,both P ＞ 0.05).Compared with baseline and the method of optimal oxygenation,VD/Vr improved significantly in ventilated patients on PEEP targeting with Ptp and lowest VD/VT (0.53±0.05,0.52±0.05 vs.0.59±0.05,0.58±0.04,all P ＜ 0.05).Conclusion Titration the optimal PEEP level with the method of Ptp could promote collapse alveolar recruitment,improve oxygenation and lung compliance,decrease dead space ventilation,and will not cause alveolar excessive inflation in patients who undergoing mechanical ventilation with early ARDS.