OptiPEEP – Supplemental tables

(1)

1

OptiPEEP – Supplemental tables

Supplemental Table 1 (ST1): Lung Ultrasound Score Criteria

Aeration Characteristic on ultrasound Score

Normal aeration 0 - 2 B-lines 0

Small loss of aeration ≥ 3 B-lines 1

Moderate loss of aeration Multiple coalescent B-lines 2

Severe loss of aeration Consolidation 3

(2)

2

Supplemental Table 2 (ST2) Atelectasis, lung stress, dead space, ventilation and hemodynamics at each level of PEEP

PEEP 15 PEEP 10 PEEP 5 p

Atelectasis

Lung ultrasound score (% maximal score) 11 [0–22] 27 [11–39] 53 [42–61] < 0.001 End-expiratory transpulmonary pressure

(cmH2O) 0.9 [-0.6–1.7] -0.3 [-2.0–0.7] -1.9 [-4.6 – -0.9] < 0.001

PaO2/FIO2 ratio (mmHg) * 471 [435–538] 458 [410–537] 431 [358–492] < 0.001 Mean airway pressure (cmH2O) 18.8 [18.6–19.2] 14.0 [13.8–14.5] 9.4 [9.2–10.2] < 0.001 Plateau airway pressure (cmH2O) 23.3 [22.4–24.6] 19.4 [18.5–21.1] 16.1 [15.4–17.4] < 0.001 Dynamic respiratory system compliance

(ml.cmH2O^-1) 32 [26–36] 30 [25–34] 27 [22–30] < 0.001

Lung stress

Airway driving pressure (cmH2O) 8.2 [7.5–9.5] 9.3 [8.5–11.1] 11.0 [10.3–12.2] < 0.001 Transpulmonary driving pressure (cmH2O) 4.7 [4.1–5.1] 5.2 [4.6–6.6] 6.0 [5.1–8.0] < 0.001 Dead space

VDalv / VTalv (%) † 10 [9–12] 10 [9–12] 9 [8–12] 0.225

(3)

3

Anatomical dead space (ml) † 112 [102–154] 107 [99–145] 104 [96–143] < 0.001 Dynamic intrinsic PEEP (cmH2O) 0.50 [0.48–0.55] 0.80 [0.50–0.90] 0.80 [0.45–1.15] 0.153 Ventilation

Respiratory rate (min^-1) 16 [15–16] 16 [15–17] 16 [15–17] 0.074

Tidal volume (ml) 355 [308–400] 360 [310–401] 362 [312–402] 0.036

Minute volume (l.min^-1) 5.3 [4.6–5.8] 5.4 [4.7–6.1] 5.4 [4.8–6.2] < 0.001

End-tidal CO2 (mmHg) 39 [39–41] 40 [39–41] 40 [38–42] 0.484

PaCO2 (mmHg) * 40 [38–41] 40 [39–41] 40 [38–42] 0.230

Hemodynamics

Mean arterial pressure (mmHg) 105 [98–111] 101 [92–106] 98 [88–104] < 0.001

Data are presented as median [25^th percentile – 75^th percentile]. The Friedman test was used. Overall n = 19; † n = 15; * n = 18

PaO2/FIO2 ratio: ratio of partial pressure of arterial oxygen to inspired fraction of oxygen; PaCO2: partial pressure of arterial carbon dioxide; PEEP:

positive end-expiratory pressure; VDalv: alveolar dead space volume; VTalv: alveolar tidal volume