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. 2021 Mar 19;21:84. doi: 10.1186/s12871-021-01268-y

Table 2.

Intraoperative ventilatory setting by group

All patients
(N = 2034)
Closed
abdominal surgery
(N = 906)
Open
abdominal surgery
(N = 1128)
P–value Absolute Difference
Ventilation mode, % (n/N) 0.013

Pressure–controlled

4% [1 to 8%]

 Volume–controlled 77% (1571/2034) 79% (895/906) 75% (676/1128)
 Pressure–controlled 23% (463/2034) 21% (233/906) 25% (230/1128)
Tidal Volume
 Absolute (ml) 505 [465 to 570] 504 [462 to 570] 505 [465 to 572] 0.567 1 [24 to 25]
 Per PBW (ml∙kg− 1) 8.0 [7.0 to 9.0] 8.5 [7.6 to 9.5] 8.2 [7.4 to 9.2] 0.001 0.2 [0.07 to 0.5]
 Per ABW (ml∙kg− 1) 7.0 [6.0 to 8.0] 6.8 [5.8 to 7.7] 7.0 [6.1 to 7.9] <  0.001 0.2 [0.1 to 0.4]
Minute ventilation (L∙kg− 1) 6.0 [6.0 to 7.0] 6.5 [5.8 to 7.2] 6.3 [5.5 to 7.0] <  0.001 0.2 [0.1 to 0.4]
Respiratory system compliance
 Dynamic, ml∙cm∙H2O−1 26 [21 to 32] 25 [20 to 32] 27 [21 to 33] <  0.001 2 [0 to 4]
 Static, ml∙cm∙H2O−1 42 [35 to 50] 41 [33 to 50] 43 [36 to 51] <  0.001 1 [0.4 to 2]
Routine recruitment maneuvers, % (n/N) 12% (238/2.029) 13% (119/905) 11% (119/1.124) 0.087 2% [1 to 5%]
FiO2, % 50 [45 to 56] 54 [48 to 70] 50 [45 to 63] <  0.001 4 [4 to 10]
SpO2, % 99 [98 to 100] 99 [98 to 100] 99 [98 to 100] <  0.001 0 [0 to 0]a
EtCO2, kPa 4.0 [4.0 to 5.0] 4.6 [4.2 to 4.9] 4.3 [4.0 to 4.7] <  0.001 0.2 [0.2 to 0.6]
Airway pressures
Driving pressure
 Time–weighted average (cmH2O∙hour−1) 8 [6 to 11] 8 [6 to 11] 8 [6 to 10] 0.091 0.2 [0.09 to 1.2]
 Maximum value (cmH2O) 14 [11 to 18] 16 [12 to 20] 14 [11 to 17] <  0.001 2 [2 to 7]
 Minimum value (cmH2O) 11 [9 to 14] 11 [9 to 15] 11 [9 to 14] 0.008 0 [0 to 17]
 Coefficient of variation (%) 10 [5 to 20] 15 [6 to 26] 9 [4 to 15] <  0.001 5 [4 to 8]
Peak pressure
 Time–weighted average (cmH2O∙hour−1) 12 [9 to 15] 11 [9 to 15] 12 [9 to 15] 0.414 0.2 [0.1 to 1.1]
 Highest value (cmH2O) 20 [17 to 24] 21 [18 to 26] 19 [16 to 23] <  0.001 2 [2 to 10]
 Lowest value (cmH2O) 16 [14 to 20] 17 [14. to 20] 16 [14 to 20] 0.011 1 [1 to 3]
 Coefficient of variation (%) 8 [4 to 15] 11 [5 to 19] 7 [3 to 12] <  0.001 5 [3 to 6]
PEEP
 Time–weighted average (cmH2O∙hour−1) 2 [1 to 3] 2 [1 to 4] 2 [1 to 3] 0.019 0 [0 to 0]
 Highest value (cmH2O) 5 [2 to 5] 5 [2 to 5] 5 [2 to 5] 0.255 0 [0 to 0]
 Lowest value (cmH2O) 4 [0 to 5] 4 [0 to 5] 3 [0 to 5] 0.186 1 [1 to 5]
 Coefficient of variation (%) 0 [0 to 22] 0 [0 to 22] 0 [0 to 22] 0.579 0 [0 to 0]

Data are presented as median [25th–75th percentile] or % (n/N). For binary and continuous variables risk difference and median difference with confidence intervals are reported respectively. Abbreviations: EtCO2 End-tidal CO2, FiO2 Fraction of inspired oxygen, SpO2 Peripheral oxygen saturation, OR Odds ratio

aDifference between groups is significant but very small and masked by rounding process