Table 2.

Ventilatory settings and monitoring parameters during pre-, first-, and last-prone sessions.

Variables∗	Survivors	Nonsurvivors	p value	Effects (p value)∗
				Survival	Time	Survival × time
Mechanical power (J/min)				0.004	0.004	0.009
Preprone	26.0 ± 2.34a	29.2 ± 2.64a	0.073
First prone	25.7 ± 2.0a	26.9 ± 2.4a	0.445
Last prone	26.0 ± 2.3a	32.9 ± 2.8b	<0.001
Ventilatory ratio				<0.001	<0.001	0.009
Preprone	2.0 ± 0.14a	2.4 ± 0.2a	<0.001
First prone	2.1 ± 0.16ab	2.5 ± 0.17a	<0.001
Last prone	2.2 ± 0.16b	3.0 ± 0.24b	<0.001
PaO2/FiO2 ratio				0.001	<0.001	0.001
Preprone	115.0 ± 4.0a	117.0 ± 3.0a	0.144
First prone	270.0 ± 20.0b	202.0 ± 11.0b	0.003
Last prone	283.0 ± 20.0b	181.0 ± 11.0b	<0.001
Driving pressure (cm H2O)				0.570	<0.001	0.467
Preprone	13.6 ± 0.45b	13.6 ± 0.51b	0.971
First prone	11.7 ± 0.5a	12.3 ± 0.5a	0.360
Last prone	11.6 ± 0.54a	12.5 ± 0.78ab	0.325
PEEP (cm H2O)				0.794	0.008	0.089
Preprone	12.0 ± 0.26a	12.0 ± 0.4b	0.929
First prone	12.0 ± 0.24a	11.4 ± 0.39a	0.185
Last prone	12.3 ± 0.33a	12.6 ± 0.42b	0.643
Tidal volume (ml/kg PBW)				0.842	0.435	0.397
Preprone	6.6 ± 0.13a	6.8 ± 0.15a	0.329
First prone	6.6 ± 0.12a	6.7 ± 0.15a	0.797
Last prone	6.5 ± 0.11a	6.7 ± 0.14a	0.378
Respiratory rate (mpm)				0.025	<0.001	0.482
Preprone	23.7 ± 3.6a	25.2 ± 3.7a	0.045
First prone	25.2 ± 3.4a	26.2 ± 3a	0.136
Last prone	25.8 ± 3.5a	27.4 ± 3.7a	0.04

PaO₂ = arterial oxygen pressure; FiO₂ = inspired oxygen; PEEP = end-expiratory positive pressure.^∗Mean ± standard deviation. ^∗p values adjusted by SAPS III, number of days on MV, and number of prone maneuvers and age; ^abequal letters do not differ by the least significant difference (LSD) test at 5% significance.