Table 1 Baseline characteristics of study participants
Variable | All patients (n = 124) | Respiratory drive present (n = 68) | Respiratory drive absent (n = 56) | Difference (95% CI) |
|---|---|---|---|---|
Age, years | 58 ± 15 | 61 ± 15 | 55 ± 16 | 5 (0–11) |
Female | 60 (48.4%) | 35 (51.5%) | 25 (44.6%) | 6.8 (− 10.8 to 24.5) |
Body mass index, kg/m2 | 33.1 ± 12.2 | 31.6 ± 12.5 | 35.0 ± 11.8 | − 3.4 (− 7.8 to 0.9) |
APACHE-II | 27 ± 7 | 26 ± 7 | 28 ± 7 | − 2 (− 5 to 0) |
SOFA | 11 ± 4 | 10 ± 3 | 12 ± 4 | − 2 (− 3 to 0) |
Duration of invasive ventilation prior to enrollment, hours | 23 ± 12 | 21 ± 12 | 25 ± 13 | -4 (-8 to 0) |
Concomitant diagnoses | ||||
 Pneumonia | 94 (75.8%) | 50 (73.5%) | 44 (78.6%) | − 5.0 (− 20.1 to 10.0) |
Sepsis | 109 (87.9%) | 59 (86.8%) | 50 (89.3%) | − 2.5 (− 13.9 to 8.9) |
Shock requiring vasopressor or inotrope | 68 (54.8%) | 33 (48.5%) | 35 (62.5%) | − 14.0 (− 31.4 to 3.4) |
Sedation depth, Richmond agitation-sedation scale (RASS) | − 3 [− 4 to − 2] | − 3 [− 4 to − 2] | − 4 [− 4 to − 2] | 0 (0–1) |
Arterial blood gas | ||||
 pH | 7.34 ± 0.08 | 7.36 ± 0.08 | 7.33 ± 0.09 | 0.03 (0.00 to 0.06) |
 PaCO2, mm Hg | 44 ± 11 | 42 ± 9 | 45 ± 13 | -2 (-6 to 2) |
 PaO2, mm Hg | 78 ± 24 | 75 ± 18 | 81 ± 30 | -5 (-14 to 3) |
PaO2:FiO2 | 107 ± 37 | 106 ± 32 | 107 ± 42 | − 1 (− 14 to 12) |
Tidal volume, mL | 398 ± 73 | 384 ± 67 | 415 ± 77 | − 31 (− 57 to − 5) |
Tidal volume, mL/kg PBW | 6.5 ± 1.1 | 6.5 ± 1.0 | 6.6 ± 1.1 | − 0.1 (− 0.5 to 0.3) |
Set PEEP, cm H2O | 13 ± 4 | 12 ± 4 | 14 ± 4 | − 2 (− 3 to 0) |
Respiratory rate, breaths/min | 25 ± 5 | 25 ± 5 | 25 ± 5 | 0 (− 1 to 2) |
Minute ventilation, L/min | 9.9 ± 2.5 | 9.8 ± 2.3 | 10.1 ± 2.7 | − 0.3 (− 1.2 to 0.5) |
Ventilatory ratio | 1.9 ± 0.5 | 1.9 ± 0.5 | 1.9 ± 0.5 | 0.0 (− 0.2 to 0.2) |
Mechanics | ||||
 Plateau pressure, cm H2O | 27 ± 5 | 26 ± 6 | 28 ± 5 | − 2 (− 4 to − 1) |
 Airway driving pressure, cm H2O | 13 ± 4 | 13 ± 4 | 13 ± 3 | 0 (− 2 to 1) |
 Lung end-inspiratory pressure, cm H2O | 8 ± 5 | 8 ± 5 | 7 ± 5 | 2 (0–4) |
 Lung end-expiratory pressure, cm H2O | − 2 ± 4 | − 1 ± 4 | − 2 ± 5 | 1 (0–3) |
 Respiratory system compliance, cm H2O | 34 ± 14 | 34 ± 17 | 33 ± 10 | 1 (− 4 to 6) |
 Lung compliance, mL/cm H2O | 50 ± 25 | 49 ± 25 | 52 ± 25 | − 2 (− 11 to 7) |
Assigned to esophageal pressure-guided PEEP trial arm | 62 (50.0%) | 31 (45.6%) | 31 (55.4%) | − 9.8 (− 27.4 to 7.8) |