Table 2.

Haemodynamic and respiratory variables

Variables	High-PEEPstart	Low-PEEP15′	Low-PEEP45′	High-PEEPend
Heart rate (min−1)	89 ± 18	90 ± 19	91 ± 19	91 ± 19
Systolic arterial pressure (mmHg)	130 ± 25	132 ± 19	129 ± 19	124 ± 17
Diastolic arterial pressure (mmHg)	65 ± 20	63 ± 10	62 ± 11	62 ± 10
Mean arterial pressure (mmHg)	86 ± 16	86 ± 13	85 ± 14	83 ± 11
Central venous pressure (mmHg)	15 ± 4	12 ± 4*	12 ± 4*	15 ± 4**
Cardiac index (L/min/m2)	2.77 ± 0.79	3.08 ± 0.85*	3.12 ± 0.90*	2.81 ± 0.89**
Cardiac function index (min−1)	4.0 ± 1.2	4.3 ± 1.3*	4.3 ± 1.3*	4.1 ± 1.3**
Global end-diastolic volume indexed (mL/m2)	750 ± 116	787 ± 168*	791 ± 150*	748 ± 127**
Extravascular lung water (mL/kg)	20 ± 4	18 ± 4*	18 ± 4*	20 ± 5**
Pulmonary vascular permeability index	3.6 ± 1.0	3.5 ± 1.0*	3.5 ± 1.0*	3.6 ± 0.9
Pulse pressure variation (%)	7 [4–14]	6 [4–12]	8 [4–12]	7 [5–11]
Stroke volume variation (%)	8 [5–13]	7 [4–13]	7 [5–13]	8 [6–13]
PEEP (cmH2O)	14 ± 2	5 ± 0*	5 ± 0*	14 ± 2**
Pplateau (cmH2O)	28 ± 2	20 ± 3*	20 ± 3*	28 ± 2**
Respiratory system compliance (mL/cmH2O)	27 [22–32]	26 [24–28]	25 [23–28]	27 [23–31]
SpO2 (%)	98 ± 2	96 ± 3*	95 ± 4*	98 ± 2**
SaO2 (%)	97 ± 3	94 ± 5*	93 ± 6+*	96 ± 4**
PaO2/FiO2 ratio	184 ± 76	150 ± 69*	147 ± 68*	178 ± 76**

FiO₂ inspired oxygen fraction, PEEP positive end-expiratory pressure, Pplateau plateau pressure, PaO₂ arterial oxygen partial pressure, SaO₂ arterial oxygen saturation, SpO₂ pulse oxygen saturation

*p < 0.05 vs. High-PEEP_start, **p < 0.05 vs. Low-PEEP_45′. See Additional file 2: Table S2 for post hoc comparisons