Oxygenation versus driving pressure for determining the best positive end-expiratory pressure in acute respiratory distress syndrome

Objective: The aim of this prospective longitudinal study was to compare driving pressure and absolute PaO2/FiO(2) ratio in determining the best positive end-expiratory pressure (PEEP) level. Patients and methods: In 122 patients with acute respiratory distress syndrome, PEEP was increased until plateau pressure reached 30 cmH(2)O at constant tidal volume, then decreased at 15-min intervals, to 15, 10, and 5 cmH(2)O. The best PEEP by PaO2/FiO(2) ratio (PEEPO2) was defined as the highest PaO2/FiO(2) ratio obtained, and the best PEEP by driving pressure (PEEPDP) as the lowest driving pressure. The difference between the best PEEP levels was compared to a non-inferiority margin of 1.5 cmH(2)O. Main results: The best mean PEEPO2 value was 11.9 +/- 4.7 cmH(2)O compared to 10.6 +/- 4.1 cmH(2)O for the best PEEPDP: mean difference = 1.3 cmH(2)O (95% confidence interval [95% CI], 0.4-2.3; one-tailed P value, 0.36). Only 46 PEEP levels were the same with the two methods (37.7%; 95% CI 29.6-46.5). PEEP level was >= 15 cmH(2)O in 61 (50%) patients with PEEPO2 and 39 (32%) patients with PEEPDP (P = 0.001). Conclusion: Depending on the method chosen, the best PEEP level varies. The best PEEPDP level is lower than the best PEEPO2 level. Computing driving pressure is simple, faster and less invasive than measuring PaO2. However, our results do not demonstrate that one method deserves preference over the other in terms of patient outcome.

Automated summary

The aim of this study is to compare the effects of driving pressure and PaO2/FiO2 ratio in determining the best PEEP level. The results show that the best PEEP level varies depending on the method chosen, but it is unclear which method is superior in terms of patient outcomes.