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 PaO/FiO 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 cmHO at constant tidal volume, then decreased at 15-min intervals, to 15, 10, and 5 cmHO. The best PEEP by PaO/FiO ratio (PEEP) was defined as the highest PaO/FiO ratio obtained, and the best PEEP by driving pressure (PEEP) as the lowest driving pressure. The difference between the best PEEP levels was compared to a non-inferiority margin of 1.5 cmHO.

MAIN RESULTS

The best mean PEEP value was 11.9 ± 4.7 cmHO compared to 10.6 ± 4.1 cmHO for the best PEEP: mean difference = 1.3 cmHO (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 cmHO in 61 (50%) patients with PEEP and 39 (32%) patients with PEEP (P = 0.001).

CONCLUSION

Depending on the method chosen, the best PEEP level varies. The best PEEP level is lower than the best PEEP level. Computing driving pressure is simple, faster and less invasive than measuring PaO. However, our results do not demonstrate that one method deserves preference over the other in terms of patient outcome.

CLINICAL TRIAL NUMBER

#ACTRN12618000554268 . Registered 13 April 2018.