Table 1. Median Initial V_T (ml/kg PBW) per Institution by Subgroup Analysis.

Patient counts for each institution and the entire cohort and median initial V_T (ml/kg PBW or ABW) for the cohort and median initial V_T (ml/kg PBW) for high risk subgroups – BMI > 30 kg/m², height < 165 cm, and female sex.

Institution	Patient Count	Initial median VT (ml/kg PBW)a	Initial Median VT (ml/kg ABW)a	BMI > 30 Initial median VT (ml/kg PBW)b*	BMI ≤ 30 Initial median VT (ml/kg PBW)a	Height < 165cm Initial median VT (ml/kg PBW)c*	Height ≥ 165cm Initial median VT (ml/kg PBW)a	Female Initial median VT (ml/kg PBW)a*	Male Initial median VT (ml/kg PBW)a
1	3,177	6.28 ± 1.69	5.14 ± 1.51	6.55 ± 1.81	6.22 ± 1.59	7.11 ± 1.87	6.04 ± 1.46	6.80 ± 1.77	5.92 ± 1.45
2	416	6.88 ± 1.97	5.55 ± 1.75	6.89 ± 1.89	6.89 ± 2.01	7.78 ± 2.45	6.77 ± 1.75	7.57 ± 1.94	6.59 ± 1.94
3	1,443	6.50 ± 1.94	5.34 ± 1.58	7.00 ± 2.11	6.42 ± 1.77	7.40 ± 2.10	6.14 ± 1.64	7.16 ± 2.09	6.11± 1.62
4	573	6.32 ± 2.17	5.32 ± 1.89	6.93 ± 2.45	6.31 ± 1.99	7.28 ± 2.38	6.06 ± 1.89	6.96 ± 2.34	5.99 ± 1.86
All Institutions	5,609	6.49 ± 1.82	5.22 ± 1.58	6.86 ± 1.97 (n=1,816)	6.31 ± 1.70	7.33 ± 2.01 (n = 1,829)	6.09 ± 1.57	7.05 ± 1.92 (n = 2,597)	6.00 ± 1.56

^*There were no significant interactions between institution and BMI, height, or female sex. These subgroups were selected a priori based on their previous identification as risk factors for receiving high V_T.

V_T = tidal volume; ml = milliliter; kg = kilogram; PBW = predicted body weight; ABW = actual body weight; BMI = body mass index

^aStatistically significant inter-institution variability in overall initial V_T (ml/kg PBW), p<0.001

^bStatistically significant inter-institution variability in overall initial V_T (ml/kg PBW), p=0.004

^cStatistically significant inter-institution variability in overall initial V_T (ml/kg PBW), p=0.008