Optimal method for selecting PEEP level in ALI/ARDS patients under mechanical ventilation.

Abstract

The PEEP in ALI/ARDS had been used since its' description (1967). Up-to-date no optimal approach to PEEP setting had been introduced, however common approaches that had been introduced included Pressure volume curves, increasing PEEP trial, decreasing PEEP trial & PEEP/FiO2 tables adopted by ARDS network. The present work assessed the safety and efficacy of three introduced approaches for PEEP setting namely increasing PEEP trial, decreasing PEEP trial and PEEP/FiO2 table. Sixty patients fulfilling the American-European Consensus Conference (AECC) criteria for ALI/ARDS were enrolled in this study, patients were randomly allocated into three equal groups (n = 20) 1, 2 & 3 using closed envelope technique. In GA: patients received an increasing PEEP trial, GB: patients received a decreasing PEEP trial and GC: PEEP was set according to PEEP/FiO2 tables of the ARDS network trial. Hemodynamic parameters (mean arterial blood pressure (MAP) and heart rate (Hr) were recorded. Respiratory & oxygenation parameters (peak airway pressure (Paw), plateau pressure (Pplat), mean airway pressure (Pmean), PEEP, PaO2, PaO2/FiO2 and arterial oxygen saturation (Sao2) were also recorded at eight specific times, prior to randomization (baseline), following PEEP setting and twice daily for 72 hours. Both increasing and decreasing PEEP trials were considered superior to PEEP/FiO2 tables in identifying desired PEEP level. Although increasing and decreasing PEEP trials had demonstrated increased PaO2, and decreased FiO2 and better PaO2/FiO2 ratios compared to baseline values, however increasing PEEP trial was associated with lower Paw and Pplat due to lower PEEP values compared to decreasing PEEP trial. Decremental trial was associated with best PaO2, FiO2, and PaOz/FiO2 compared to increasing PEEP trial and PEEP/FiO2 tables.