Table 2.
Non-OLS (n = 130) | OLS (n = 130) | P value | |
Immediately before surgery | |||
PEEP (cmH2O) | 0 [0 to 0] | 8 [8 to 8] | <0.001 |
Fraction of inspired oxygen (%) | 45 [44 to 45] | 45 [44 to 45] | 0.679 |
Tidal volume (ml kg−1 PBW) | 7.6 ± 0.7 | 7.5 ± 0.6 | 0.343 |
Respiratory rate (breaths min−1) | 12 [12 to 12] | 12 [12 to 12] | 0.346 |
Peak pressure (cmH2O) | 14 ± 3 | 17 ± 2 | <0.001 |
Plateau pressure (cmH2O) | 11 ± 2 | 14 ± 2 | <0.001 |
Driving pressure (cmH2O) | 11 ± 2 | 6 ± 2 | <0.001 |
Respiratory compliance (ml cmH2O−1) | 34 ± 8 | 50 ± 13 | <0.001 |
1.5 h after pneumoperitoneum | |||
PEEP (cmH2O) | 0 [0 to 0] | 8 [8 to 8] | <0.001 |
Fraction of inspired oxygen (%) | 45 [44 to 45] | 45 [45 to 45] | 0.279 |
Tidal volume (ml kg−1 PBW) | 7.1 ± 0.8 | 7.0 ± 0.7 | 0.179 |
Respiratory rate (breaths min−1) | 16 [15 to 18] | 16 [15 to 18] | 0.283 |
Peak pressure (cmH2O) | 21 ± 4 | 24 ± 3 | <0.001 |
Plateau pressure (cmH2O) | 17 ± 4 | 20 ± 3 | <0.001 |
Driving pressure (cmH2O) | 17 ± 4 | 12 ± 3 | <0.001 |
Respiratory compliance (ml cmH2O−1) | 21 ± 6 | 27 ± 8 | <0.001 |
PaO2/FiO2 (kPa) | 49.7 ± 14.7 | 58.8 ± 12.1 | <0.001 |
Lung recruitment manoeuvres (times) | 0 [0 to 0] | 7 [6 to 8] | <0.001 |
Duration of surgery (min) | 214 ± 80 | 212 ± 81 | 0.817 |
Duration of mechanical ventilation (min) | 230 ± 82 | 229 ± 81 | 0.951 |
Trendelenburg position | 109 (83.8) | 98 (75.4) | 0.123 |
Pneumoperitoneum pressure (mmHg) | 12 [11 to 12] | 12 [11 to 12] | 0.105 |
Duration of pneumoperitoneum (min) | 164 ± 73 | 158 ± 74 | 0.512 |
Muscle relaxant antagonist | 121 (96.0) | 122 (94.6) | 0.769 |
Epidural analgesia | 129 (99.2) | 129 (99.2) | 1.000 |
Urine output (ml) | 500 [300 to 712] | 500 [300 to 700] | 0.334 |
Blood loss (ml) | 50 [50 to 100] | 50 [50 to 100] | 0.290 |
Volume of fluids administered (ml) | 3161 ± 695 | 3227 ± 663 | 0.436 |
Crystalloid (ml) | 2039 ± 488 | 2025 ± 505 | 0.831 |
Red blood cell infusion | 5 (3.8) | 6 (4.6) | 1.000 |
Data are number (%), mean ± SD or median [IQR]. Ten patients in each group were excluded from the study. OLS, open-lung strategy; PBW, predicted body weight; PEEP, positive end-expiratory pressure. Respiratory compliance = tidal volume/(peak pressure − PEEP); driving pressure = plateau pressure − PEEP.