highly significantp = 0.0006
Pre-pronation values of the PaO 2 /FiO 2 ratio were significantly different between groups (group S vs D: 150 ± 56 vs 115 ± 46; p = 0.006), but only pre-pronation FiO 2 remained highly significant at multivariate analysis (0.67 ± 0.16 vs 0.82 ± 0.18; univariate p = 0.0006, multivariate p = 0.001, OR 6.11).