Fig. 2

Effects of FiO₂sT ≤ 0.60 and > O.21 (FiO₂ ≤ 0.60/ > O.21) vs. FiO₂s = 0.21 (controls) on standardized mean differences (± SD) (SMD) in lung weights and lung lavage protein in studies [author (y)] that also administered animals an infectious or noninfectious inflammatory challenge. Animal type, FiO₂ level and duration, inflammatory challenge route and type employed in studies are shown. Data from studies used to calculate SMDs for these parameters and parameter units are shown in Additional file 1: Table S2. Open circles represent results from individual regimens of oxygen or challenge within studies examining more than one regimen, that could be pooled (I² level of significance, p ≥ 0.10) to report an overall SMD for the study, shown by solid circles. Results shown by solid circles were then used to determine whether SMDs could be pooled across studies in the same species and then across all studies. Also shown are the number of animals (n) in study groups. While an overall SMD could be calculated across studies for lung weights (I² = 0%, p = 0.50; inverted triangle), differences between mouse and rat studies prevented this for lung protein (I² = 43%, p = 0.07). CLP cecal ligation and puncture, IT intratracheal, IC intracardiac, K. p. Klebsiella pneumoniae, HCL hydrochloric acid, LPS lipopolysaccharide, OA oleic acid