Table 2.

Observations characteristics stratified by PEEP groups

Characteristic	PEEP ≤ 5cm	8 ≤ PEEP ≤10cm	12 ≤ PEEP ≤ 15cm	PEEP ≥ 16cm
# of observations	328	375	97	33
Cardiac index* (l/min/m2)	4.2 ± 1.1	4.2 ± 1.3	4.3 ± 1.2	4.6 ± 1.5
CVP (cm water)	10 ± 4	12 ± 4	13 ± 5	15 ± 5
PAOP (cm water)	13 ± 5	15 ± 5	16 ± 5	18 ± 5
PaO2/FiO2 ratio	224 ± 75	166 ± 67	112 ± 49	81 ± 25
Plateau pressure (cm water)	20 ± 5	24 ± 5	29 ± 6	33 ± 8
Lung Compliance (ml / cm water)	29 ± 13	31 ± 16	30 ± 21	31 ± 34
FACTT study arm, % in liberal fluid arm	47%	50%	64%	70%

Observations characteristics stratified by PEEP groups (N=833 dual measurements). Please note that there were no observations in the study group that had PEEP values of 6cm, 7cm, or 11cm, and there was only one observation with a PEEP of 13 cm and another observation with a PEEP of 15 cm.

PEEP: positive end-expiratory pressure. CVP: central venous pressure. PAOP: pulmonary artery occlusion pressure, also known as wedge pressure.

^*The differences in cardiac index between the 4 PEEP categories were not statistically significant when adjusted for in the multiple linear regression model (p=0.5)