Fig. 4
Effects of FiO2s ≤ 0.60 and > O.21 (FiO2 ≤ 0.60/ > O.21) (upper panel) or FiO2 > 0.60 (lower panel) vs. FiO2s = 0.21 (controls) on standardized mean differences (± SD) (SMD) in body weights in grams in studies [author (y)] that did not include an infectious or noninfectious inflammatory challenge. Animal type, increased FiO2 level, and duration employed in studies or groups are shown. Also shown for each study or group are the standardized means (± SD) and numbers of animals (n) used to calculate individual SMDs. Data from studies used to calculate SMDs for these parameters and parameter units are shown in Additional file 1: Table S6. Analysis for two studies (Coursin and Nylen) that included more than one regimen of FiO2 ≤ 0.60/ > O.21 or FiO2 > 0.60 showed that the levels of significance for heterogeneity (I2 ≥ 50%, p ≤ 0.09) across these regimens prevented pooling groups and these groups are shown as solid circles and used in analysis individually here. Heterogeneity across studies and groups also prevented calculating overall SMDs for FiO2 ≤ 0.60/ > O.21 (I2 = 71%, p < 0.01) and FiO2 > 0.60 (I2 = 78%, p < 0.01)