Background
Methods
Study population
Study protocol
Data collection
Gas exchange, respiratory mechanics and lung CT data
Statistical analysis
Results
Response to 5–15 cmH 2 O of PEEP on partitioned respiratory mechanics, gas exchange and dead space
Variables | PEEP 5 61 patients | PEEP 15 61 patients | p |
---|---|---|---|
Plateau pressure, cmH2O | 17 ± 3 | 28 ± 3 | < 0.001 |
Driving pressure, cmH2O | 12 ± 3 | 13 ± 3 | 0.071 |
Respiratory system elastance, cmH2O/L | 23 [19–27] | 24 [21–31] | 0.093 |
Lung elastance, cmH2O/L | 18 [15–22] | 19 [17–25] | 0.049 |
Chest wall elastance, cmH2O/L | 5 [3–6] | 4 [3–6] | 0.845 |
Lung stress, cmH2O | 13.1 ± 3.1 | 22.3 ± 4.0 | < 0.001 |
Mechanical power, J/min | 16.7 ± 5.7 | 26.1 ± 6.4 | < 0.001 |
Mechanical Power_Compliancers, J/min/(mL/cmH2O) | 0.36 [0.27–0.50] | 0.61 [0.51–0.77] | < 0.001 |
PaO2, mmHg | 63 [55–76] | 84 [74–99] | < 0.001 |
PaO2/FiO2, mmHg | 82 [66–138] | 127 [90–184] | < 0.001 |
Right-to-left shunt, % | 47 ± 15 | 35 ± 12 | < 0.001 |
PvO2, mmHg | 42 ± 7 | 47 ± 7 | < 0.001 |
ScvO2, % | 74 ± 8 | 79 ± 6 | < 0.001 |
Ca-vO2, mL | 2.8 [2.3–3.2] | 3.0 [2.4–3.4] | 0.024 |
PaCO2, mmHg | 48 ± 9 | 50 ± 9 | < 0.001 |
Ventilatory ratio | 1.66 ± 0.39 | 1.74 ± 0.37 | 0.002 |
Estimated physiological dead space | 0.50 [0.43–0.58] | 0.52 [0.42–0.60] | < 0.001 |
Response to 5–15 cmH 2 O of PEEP according to the compliance of respiratory system and severity of hypoxemia
Variables | Low Crs < 44 mL/cmH2O 30 patients | High Crs ≥ 44 mL/cmH2O 31 patients | p |
---|---|---|---|
Δ15-5 Plateau pressure, cmH2O | 10 [7–12] | 11 [10–13] | 0.042 |
Δ15-5 Driving pressure, cmH2O | 0 [− 3 to 2] | 1 [0–3] | 0.042 |
Δ15-5 Respiratory system elastance, cmH2O/L | − 1 [− 5 to 4] | 2 [0–6] | 0.057 |
Δ15-5 Lung elastance, cmH2O/L | 2 [− 2 to 5] | 2 [0–5] | 0.286 |
Δ15-5 Chest wall elastance, cmH2O/L | 0 [− 2 to 2] | 0 [− 1 to 0] | 0.305 |
Δ15-5 Lung stress, cmH2O | 9 [6–11] | 9 [8–12] | 0.256 |
Δ15-5 Mechanical power, J/min | 9 [8–12] | 9 [8–11] | 0.866 |
Δ15-5 Mechanical Power_Compliancers, J/min/(mL/cmH2O) | 0.26 [0.12–0.40] | 0.23 [0.16–0.35] | 0.656 |
Δ15-5 PaO2, mmHg | 20 [13–38] | 20 [6–30] | 0.336 |
Δ15-5 PaO2/FiO2, mmHg | 28 [16–51] | 30 [10–50] | 0.657 |
Δ15-5 Right-to-left shunt, % | − 12 [− 23 to − 1] | − 9 [− 18 to − 5] | 0.710 |
Δ15-5 PvO2, mmHg | 4.0 [2.3–8.8] | 2.0 [1.0–8.1] | 0.219 |
Δ15-5 ScvO2, % | 5.5 [1.0–10.8] | 2.5 [0.0–8.1] | 0.184 |
Δ15-5 Ca-vO2, mL | 1.0 [0.3–1.7] | 0.6 [0.2–1.3] | 0.331 |
Δ15-5 PaCO2, mmHg | 1 [− 1 to 3] | 2 [1–4] | 0.226 |
Δ15-5 Ventilatory ratio | 0.04 [− 0.10 to 0.10] | 0.08 [0.02–0.20] | 0.119 |
Δ15-5 Estimated physiological dead space | 0.01 [− 0.01 to 0.03] | 0.02 [0.01–0.05] | 0.119 |
Variables | Low PaO2/FiO2 < 81.8 31 patients | High PaO2/FiO2 ≥ 81.8 30 patients | p |
---|---|---|---|
Δ15-5 Plateau pressure, cmH2O | 8 [10–11] | 11 [10–13] | 0.147 |
Δ15-5 Driving pressure, cmH2O | 0 [− 2 to 1] | 1 [0–3] | 0.147 |
Δ15-5 Respiratory system elastance, cmH2O/L | 0 [− 3 to 3] | 3 [0–6] | 0.126 |
Δ15-5 Lung elastance, cmH2O/L | 2 [− 2 to 4] | 3 [1–7] | 0.257 |
Δ15-5 Chest wall elastance, cmH2O/L | 0 [− 2 to 1] | 0 [− 2 to 2] | 0.373 |
Δ15-5 Lung stress, cmH2O | 9 [7–11] | 9 [8–13] | 0.534 |
Δ15-5 Mechanical power, J/min | 9 [8–11] | 10 [9–11] | 0.351 |
Δ15-5 Mechanical Power_Compliancers, J/min/(mL/cmH2O) | 0.21 [0.12–0.34] | 0.30 [0.17–0.37] | 0.436 |
Δ15-5 PaO2, mmHg | 26 [16–38] | 16 [4–23] | 0.012 |
Δ15-5 PaO2/FiO2, mmHg | 31 [16–55] | 28 [9–42] | 0.212 |
Δ15-5 Right-to-left shunt, % | − 16 [− 26 to − 10] | 0 [− 11 to 0] | < 0.001 |
Δ15-5 PvO2, mmHg | 3 [2–11] | 1 [0–2] | < 0.001 |
Δ15-5 ScvO2, % | 8.5 [4.4–13.4] | 0.6 [− 1 to 3] | < 0.001 |
Δ15-5 Ca-vO2, mL | 1.3 [0.9–1.8] | 0.4 [0.0–0.6] | < 0.001 |
Δ15-5 PaCO2, mmHg | 1 [− 2 to 3] | 2 [1–5] | 0.110 |
Δ15-5 Ventilatory ratio | 0.04 [− 0.09 to 0.10] | 0.08 [− 0.02 to 0.19] | 0.065 |
Δ15-5 Estimated physiological dead space | 0.01 [− 0.02 to 0.03] | 0.02 [0.01–0.05] | 0.070 |