Table 2.

Monitoring during PEEP changes in ARDS patients included in the study^a

Measurement	PEEP 5 cm H2O (N = 10)	PEEP 10 cm H2O (N = 10)	PEEP 15 cm H2O (N = 10)	P value
Arterial blood gas measurements
PaO2, mmHg	74 ± 15b	90 ± 19c	102 ± 26d	<0.001
PaCO2, mmHg	51 ± 11	50 ± 10	52 ± 12	NS (0.08)
pH	7.31 ± 0.09	7.32 ± 0.09c	7.3 ± 0.09d	0.002
SaO2, %	94 ± 3e	97 ± 3	97 ± 3f	<0.001
PaO2/FiO2	106 ± 35e	133 ± 43c	153 ± 57f	<0.001
Haemodynamic and ventilatory parameters
SAP, mmHg	126 ± 18	120 ± 15	122 ± 19	NS (0.39)
DAP, mmHg	51 ± 11	50 ± 7	53 ± 10	NS (0.4)
MAP, mmHg	76 ± 10	74 ± 7	75 ± 11	NS (0.6)
HR, beats/minute	85 ± 14	83 ± 14	85 ± 14	NS (0.6)
PIP, cmH2O	34 ± 6	37 ± 10c	43 ± 12	NS (0.06)
MIP, cmH2O	12 ± 2e	18 ± 2c	22 ± 3g	<0.001
Lung sonographic evaluation
Nonaerated lung area, cm2	27 ± 31e	20 ± 24c	11 ± 12f	0.008

^aAll data are means ± SD. PEEP, positive end-expiratory pressure; PaO₂, arterial oxygen partial pressure; FiO₂, fraction of inspired oxygen; PaCO₂, carbon dioxide partial pressure; SaO₂, oxygen saturation; SAP, systolic arterial pressure; DAP, diastolic arterial pressure; MAP, mean arterial pressure; HR, heart rate; PIP, peak inspiratory pressure; MIP, mean inspiratory pressure. ^bP < 0.01 comparing PEEP 5 and 10 cm H₂O for PaO₂ measurements. ^cP < 0.05 comparing PEEP 10 and 15 cm H₂O for PaO₂, pH, PaO₂/FiO₂, PIP, MIP and nonaerated lung area measurements. ^dP < 0.01 comparing PEEP 5 and 15 cm H₂O for PaO₂ and pH measurements. ^eP < 0.05 comparing PEEP 5 and 10 cm H₂O for SaO₂, PaO₂/FiO₂, MIP and nonaerated lung area measurements. ^fP < 0.05 comparing PEEP 5 and 15 cm H₂O for SaO₂, PaO₂/FiO₂ and nonaerated lung area measurements. ^gP < 0.001 comparing PEEP 5 and 15 cm H₂O for MIP measurements.