Introduction
Materials and methods
Patients
Ventilator setting
LTV group
APRV group
Analgesia and sedation
Procedures in both groups
Statistical analysis
Results
Patient characteristic | APRV group (n = 71) | LTV group (n = 67) |
---|---|---|
Male sex | 50 (70.4%) | 41 (61.2%) |
Age (years) | 51.5 ± 15.0 | 52.0 ± 15.1 |
Predicted body weight (kg) | 61.7 ± 8.2 | 60.5 ± 7.3 |
APACHE II score at admission | 22.0 ± 7.9 | 20.2 ± 7.6 |
Duration of mechanical ventilation (h) | 24.6 ± 12.6 | 22.1 ± 13.5 |
Duration of ICU stay before inclusion (h) | 25.6 ± 12.6 | 23 ± 13.3 |
Chronic disease | ||
Chronic obstructive pulmonary disease | 2 (2.8%) | 5 (7.5%) |
Chronic cardiac dysfunction | 2 (2.8%) | 3 (4.5%) |
Chronic renal dysfunction | 0% | 3 (4.5%) |
Hematological disease | 2 (2.8%) | 3 (4.5%) |
Hepatic disease | 3 (4.2%) | 5 (7.5%) |
Cancer | 7 (9.9%) | 12 (17.9%) |
Immunodeficiency | 4 (5.6%) | 4 (6.0%) |
Diabetes | 3 (4.2%) | 2 (3.0%) |
Coexisting one or more of the above diseases | 23 (32.4%) | 34 (50.7%) |
Reason for ARDS | ||
Pneumonia | 18 (25.4%) | 26 (38.8%) |
Extrapulmonary sepsis | 13 (18.3%) | 10 (14.9%) |
Severe acute pancreatitis | 19 (26.8%) | 13 (19.4%) |
Severe trauma | 9 (12.7%) | 7 (10.4%) |
Major surgical procedures | 8 (11.3%) | 9 (13.4%) |
Other | 4 (5.6%) | 2 (3.0%) |
Arterial blood gases at baseline | ||
pH | 7.37 ± 0.09 | 7.38 ± 0.10 |
PaCO2 (mmHg) | 40.1 ± 7.4 | 41.7 ± 10.5 |
FiO2
| 0.66 ± 0.19 | 0.62 ± 0.19 |
PaO2 (mm Hg) | 72.5 ± 13.1 | 76.8 ± 20.5 |
PaO2:FiO2 at baseline | 121.7 ± 46.8 | 138.3 ± 56.1 |
PaO2:FiO2 ≤ 150 | 47(66.2%) | 41(61.2%) |
Co-interventions | ||
Vasopressor | 40 (56.3%) | 46 (68.7%) |
Respiratory and hemodynamic parameters and analgesia and sedation variables at baseline and on days 1, 2, 3, and 7 after enrollment
Variable | Baseline | Day 3 after enrollment c,d
| ||||
---|---|---|---|---|---|---|
APRV | LTV |
P value | APRV | LTV |
P value | |
No. of patients | 71 | 67 | 62 | 56 | ||
Respiratory variables | ||||||
Ventilator setting (tidal volume in mL) | 437.8 ± 40.6 | 429.6 ± 47.5 | 0.277 | _ | 423.8 ± 51.8 | |
Ventilator setting (tidal volume in mL/kg of predicted body weight) | 7.2 ± 0.7 | 7.1 ± 0.7 | 0.534 | _ | 7.0 ± 1 | |
Ventilator monitoring (tidal volume in mL) | 466.6 ± 54.9 | 461.2 ± 59.7 | 0.578 | 476.9 ± 111.3 | 461.8 ± 64.1 | 0.364 |
Ventilator monitoring (tidal volume in mL/kg of predicted body weight) | 7.6 ± 1.1 | 7.7 ± 1.3 | 0.619 | 7.8 ± 1.9 | 7.7 ± 1.1 | 0.575 |
Ventilator setting frequency (cycles/min) | 15.1 ± 4.3 | 15.1 ± 3.8 | 0.977 | 12.7 ± 1.8 | 14.9 ± 4.8 | 0.002 |
Phigh
| _ | _ | 24.1 ± 3.6 | _ | ||
PEEP (cmH2O) | 11.4 ± 3.0 | 10.4 ± 2.6 | 0.063 | 6.9 ± 1.8 | 10.4 ± 2.8 | <0.001 |
FIO2
| 0.66 ± 0.19 | 0.62 ± 0.19 | 0.198 | 0.43 ± 0.09 | 0.53 ± 0.19 | 0.001 |
Respiratory rate (cycles/min) | 21.5 ± 6.6 | 19.5 ± 4.6 | 0.039 | 19.0 ± 6.0 | 20.3 ± 5.1 | 0.225 |
Peak inspiratory pressure (cmH2O) | 31.7 ± 4.5 | 30.4 ± 4.0 | 0.061 | 26.2 ± 3.6 | 28.5 ± 4.8 | 0.005 |
Mean airway pressure (cmH2O) | 18.3 ± 3.9 | 17.4 ± 3.5 | 0.140 | 21.8 ± 3.5 | 16.0 ± 3.3 | <0.001 |
Plateau pressure (cmH2O) | 26.5 ± 4.0 | 25.3 ± 3.6 | 0.081 | 19.3 ± 3.9 | 23.3 ± 4.6 | <0.001 |
Driving pressure (cmH2O)a
| 15.2 ± 3.6 | 14.8 ± 3.4 | 0.550 | 12.6 ± 3.5 | 12.8 ± 4.1 | 0.822 |
Respiratory system compliance (mL/cmH2O) | 30.1 ± 7.6 | 32.6 ± 7.7 | 0.058 | 43.7 ± 11.3 | 34.1 ± 8.9 | <0.001 |
Total minute ventilation (L/min)b
| 8.37 ± 2.36 | 8.42 ± 1.98 | 0.905 | 6.86 ± 2.06 | 8.22 ± 2.30 | 0.001 |
Spontaneous minute ventilation (L/min) | - | - | 1.78 ± 1.37 | - | ||
pH | 7.37 ± 0.09 | 7.38 ± 0.10 | 0.427 | 7.42 ± 0.05 | 7.42 ± 0.07 | 0.648 |
PaCO2 (mmHg) | 40.1 ± 7.4 | 41.7 ± 10.5 | 0.307 | 40.8 ± 7.3 | 42.3 ± 8.6 | 0.291 |
PaO2 (mmHg) | 72.5 ± 13.1 | 76.8 ± 20.5 | 0.149 | 116.2 ± 28.5 | 84.8 ± 20.1 | <0.001 |
PaO2:FiO2
| 121.7 ± 46.8 | 138.3 ± 56.1 | 0.060 | 280.3 ± 83.9 | 180.5 ± 68.6 | <0.001 |
Hemodynamic variables | ||||||
Heart rate (beats/min) | 105.4 ± 22.5 | 110.2 ± 24.6 | 0.238 | 92.7 ± 16.6 | 103.6 ± 19.3 | 0.001 |
Systolic blood pressure (mmHg) | 122.2 ± 17.9 | 116.2 ± 22.5 | 0.088 | 126.6 ± 18.0 | 125.0 ± 20.3 | 0.646 |
Diastolic blood pressure (mmHg) | 72.8 ± 13.2 | 68.6 ± 12.1 | 0.053 | 76.1 ± 14.5 | 69.3 ± 13.3 | 0.009 |
Mean arterial pressure (mmHg) | 87.4 ± 14.7 | 84.2 ± 13.4 | 0.194 | 92.8 ± 14.9 | 87.1 ± 13.6 | 0.032 |
Study Outcomes
Main outcome variables | APRV (n = 71) b
| LTV (n = 67) b
|
P value |
---|---|---|---|
No. of days of ventilation | 8 [5–14] | 15 [7–22] | 0.001 |
No. of ventilator-free days at 28 days | 19 [8–22] | 2 [0–15] | <0.001 |
Successful extubation | 47 (66.2%) | 26 (38.8%) | 0.001 |
Tracheostomy | 9 (12.7%) | 20 (29.9%) | 0.013 |
Length of ICU stay (days) | 15 [8–21] | 20 [10–32] | 0.015 |
Pneumothorax between day 1 and day 28a
| 3 (4.2%) | 7 (10.4%) | 0.199 |
Death during the ICU stay | 14 (19.7%) | 23 (34.3%) | 0.053 |
Length of hospital stay (days) | 21 [14–30] | 27 [18–41] | 0.055 |
Death during the hospital stay | 17 (23.9%) | 25 (37.3%) | 0.088 |
Other supportive therapies | |||
Neuromuscular blocker | 2 (2.8%) | 9 (13.4%) | 0.021 |
Recruitment maneuvers | 4 (5.6%) | 11 (16.4%) | 0.042 |
Prone position | 2 (2.8%) | 10 (14.9%) | 0.012 |
Inhaled nitric oxide | 1 (1.4%) | 1 (1.5%) | 1.000 |
High-frequency oscillatory ventilation | 1 (1.4%) | 3 (4.5%) | 0.355 |