Table 2.
Mechanical ventilation variables and V̇/Q̇ measurement during the study period
| Variable | TLV, after induction | OLV, prior to intervention | OLV, after intervention | TLV, End of surgery | ||||
|---|---|---|---|---|---|---|---|---|
| PEEPINCREMENTAL | PEEPDECREMENTAL | PEEPINCREMENTAL | PEEPDECREMENTAL | PEEPINCREMENTAL | PEEPDECREMENTAL | PEEPINCREMENTAL | PEEPDECREMENTAL | |
| Mechanical ventilation | ||||||||
| Paw (cm H2O) | 20 [15–23] | 18 [14–20.5] | 23 [19.5–27.5] | 22 [20–26] | 25.5 [22.2–30] | 24 [23–29] | 24.5 [20.7–28.2] | 18 [14–20.5] |
| Plateau pressure (cm H2O) | 13 [10–15] | 13 [10–15] | 15 [14–19] | 15 [14–19] | 19 [17–22] | 17.5 [15–21] | 19 [16–22] | 18 [15–20] |
| Driving Pressure (cm H2O) | 13 [10–15] | 12 [10–16] | 15 [14–19] | 14 [13–19] | 10 [9–11] | 8 [7–11]#* | 10 [8–12] | 9 [7–12] |
| PEEP (cm H2O) | 0 | 0 | 0 | 0 | 8 [6–12] | 8 [8–10] | 8 [6–12] | 8 [8–10] |
| Tidal volume | 440 [385–500] | 440 [400–490] | 315 [270–350] | 310 [290–350] | 315 [270–350] | 310 [290–350] | 440 [390–500] | 440 [400–490] |
| Respiratory rate | 14 [14–15] | 14 [13–15] | 16 [14–16] | 16 [14–16] | 16 [14.2–17.5] | 16 [16–18] | 16 [14–16] | 16 [14–17] |
| Mechanical power (J/m) | 10.8 [8.6–12.4] | 9.5 [8.1–12.7] | 5.6 [4.5–6.8] | 5.8 [4.4–6.6] | 6.8 [5.4–8.8]* | 7.0 [5.9–8.6]* | 12.8 [10.0–16.1] | 13.3 [11.4–15.0] |
| V/Q̇ variables | ||||||||
| Shunt (%) | 26.2 [21.8–32.9] | 24.0 [16.1–33.1] | 49.8 [39.0–55.0] | 45.2 [37.5–58.1] | 34.9 [28.0–42.1]* | 33.1 [24.7–45.1]* | 18.6 [9.0–25.2] | 18.5 [9.8–22.6] |
| Low V̇/Q̇ (mmHg) | 39 [17–65] | 35 [23–71] | 86 [37–150] | 69 [23–144] | 55 [38–75] | 57 [34–101] | 28 [22–70] | 35 [24–72] |
| High V̇/Q̇ (mmHg) | 11 [6–15] | 11 [6–15] | 13 [10–16] | 11 [7–15] | 13 [11–18] | 13 [6.7–17] | 12 [10–16] | 12 [7–17] |
Paw Peak airway pressure, PEEP positive end-expiratory pressure; V̇/Q̇ = Ventilation/perfusion ratio
#p < 0.05 vs the other group, *p < 0.05 vs prior to intervention