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Table 1 Patient’s characteristics at ICU admission, risk factors for post-extubation respiratory failure, the reason for ICU admission and characteristics before SBT performance in the overall population and subgroups

From: Electrical impedance tomography during spontaneous breathing trials and after extubation in critically ill patients at high risk for extubation failure: a multicenter observational study

  Overall SBT success
(n = 61)
SBT failure
(n = 17)
p value Extubation success (n = 39) Extubation failure (n = 22) p value
Characteristics at ICU admission
 Weight (kg) 75 [65; 83] 75 [65; 81] 75 [68; 95] 0.458 70 [62; 80] 80 [70; 86] 0.128
 Height (cm) 170 [165; 173] 170 [165; 175] 170 [163; 170] 0.286 170 [165; 175] 170 [160; 172] 0.203
 SAPS-II 52 [37; 67] 50 [34; 66] 59 [41; 68] 0.188 44 [31; 55] 63 [48; 83] < 0.001
 SOFA 6 [4; 9] 6 [4; 9] 4 [3; 7] 0.049 6 [4; 9] 7 [4; 10] 0.790
Risk factors for post-extubation respiratory failure
 PaCO2 > 45 mmHg at SBT n (%) 30 (38) 22 (36) 8 (47) 0.416 12 (31) 10 (45) 0.279
 Chronic respiratory disease n (%) 17 (22) 12 (20) 5 (29) 0.510 7 (18) 5 (23) 0.741
 Chronic heart failure n (%) 17 (22) 12 (20) 5 (29) 0.510 9 (23) 3 (14) 0.510
 Upper airway stridor n (%) 2 (3) 2 (3) 0 (0) > 0.999 2 (5) 0 (0) 0.531
 Age ≥ 65 years n (%) 48 (62) 38 (62) 10 (59) 0.786 24 (62) 14 (64) > 0.999
 Cardiac failure as reason of iMV n (%) 10 (13) 8 (13) 2 (12) > 0.999 6 (15) 2 (9) 0.699
 APACHE-II score > 12 at extubation n (%) 29 (37) 24 (39) 5 (29) 0.575 14 (36) 10 (45) 0.587
 ARF requiring > 72 h of iMV n (%) 44 (56) 30 (49) 14 (82) 0.025 19 (49) 11 (48) > 0.999
 BMI > 35 kg/m2 n (%) 11 (14) 5 (8) 6 (35) 0.011 3 (8) 2 (9) > 0.999
 Neuromuscular disease n (%) 9 (12) 4 (7) 5 (29) 0.020 3 (8) 1 (5) > 0.999
Reason for ICU admission
 Acute heart failure n (%) 10 (13) 6 (10) 4 (23) 0.212 0 (0) 6 (27) 0.013
 Acute on Chronic respiratory failure n (%) 17 (22) 12 (20) 5 (29) 0.507 7 (18) 5 (23) 0.742
 Sepsis/septic shock n (%) 21 (27) 20 (33) 1 (6) 0.031 14 (36) 6 (27) 0.577
 Trauma n (%) 10 (13) 7 (11) 3 (18) 0.682 7 (18) 0 (0) 0.042
 Pneumonia n (%) 20 16 (26) 4 (24) > 0.999 11 (28) 5 (23) 0.766
Characteristics before the SBT
 PEEP (cmH2O) 5.0 [5.0; 5.1] 5.0 [5.0; 5.1] 5.0 [5.0; 5.0] 0.168 5.0 [5.0; 5.1] 5.0 [5.0; 5.1] 0.953
 Inspiratory support (cmH2O) 10 [8; 11] 10 [8; 10] 10 [9; 11] 0.531 9 [8; 11] 10 [10; 10] 0.118
 pH 7.44 [7.41; 7.47] 7.44 [7.40; 7.48] 7.46 [7.42; 7.48] 0.546 7.45 [7.41; 7.48] 7.42 [7.40; 7.45] 0.397
 PaCO2 (mmHg) 39.3 [36.3; 45.0] 39.3 [36.0; 45.0] 39.5 [38.2; 44.4] 0.392 38.5 [34.0; 44.3] 39.3 [38.0; 47.3] 0.176
 PaO2/FiO2 (mmHg) 268 [230; 310] 274 [241; 306] 248 [205; 324] 0.347 274 [243; 303] 270 [226; 313] 0.932
  1. SBT: Spontaneous breathing trial; ICU: intensive care unit; SAPS-II: simplified acute physiology score II; SOFA: sequential organ failure assessment; PaCO2: arterial partial pressure of carbon dioxide; iMV: invasive mechanical ventilation; APACHE-II: acute physiology and chronic health evaluation II; ARF: acute respiratory failure; BMI: body mass index; PEEP: positive-end expiratory pressure; PaO2/FiO2: ratio between arterial partial pressure and inspired fraction of oxygen