Parameter | Low VT strategy | High VT strategy | Low vs. high TV | |||
---|---|---|---|---|---|---|
 | Baseline | Final | Baseline | Final | Difference P value |  |
Tidal volume (L) | 0.49 (0.1) | 0.42 (0.07) | 0.50 (0.1) | 0.72 (0.18) | -0.30 | <0.001 |
Tidal volume/ideal body weight (mL/kg) | 8 (2) | 7 (1) | 8 (2) | 12 (3) | -5 | <0.001 |
Respiratory rate (1/min) | 22 (3) | 25 (5) | 22 (5) | 15 (5) | 10 | <0.001 |
Minute ventilation (L) | 10.9 (2.2) | 10.7 (2.3) | 10.7 (2.2) | 10.2 (2.3) | 0.5 | 0.262 |
Peak airway pressure (cmH2O) | 27 (4) | 26 (4) | 28 (7) | 35 (7) | -9 | <0.001 |
Mean airway pressure (cmH2O) | 19 (4) | 18 (4) | 20 (4) | 22 (5) | -3 | 0.021 |
Dead space/tidal volume ratio | 0.61 (0.14) | 0.62 (0.14) | 0.58 (0.15) | 0.52 (0.14) | 0.10 | 0.001 |
pH | 7.37 (0.12) | 7.37 (0.14) | 7.38 (0.13) | 7.41 (0.12) | -0.04 | 0.001 |
PaCO2 (mmHg) | 47 (13) | 49 (15) | 48 (14) | 43 (12) | 6 | 0.002 |
PaO2 (mmHg) | 124 (49) | 131 (58) | 120 (38) | 117 (47) | 14 | 0.020 a |
Heart rate (1/min) | 92 (16) | 92 (15) | 91 (17) | 93 (19) | -1 | 0.521 |
Mean arterial pressure (mmHg) | 78 (10) | 75 (13) | 78 (14) | 77 (12) | -2 | 0.514 |
Cardiac index (L.min-1.m-2) | 3.8 (1.3) | 3.9 (1.2) | 3.9 (1.2) | 3.5 (1.1) | 0.4 | 0.012 |
Central venous pressure (mmHg) | 12 (5) | 11 (5) | 12 (4) | 12 (5) | -1 | 0.176 |
Systemic vascular resistance index (dyne.sec.cm-5.m-2) | 1494 (500) | 1374 (312) | 1455(432) | 1572 (469) | -198 | 0.008 |
Oxygen delivery index (mL.min-1.m-2) | 506 (181) | 521 (187) | 509 (145) | 463 (146) | 58 | 0.002 |
Oxygen consumption index (mL.min-1.m-2) | 171 (55) | 172 (43) | 182 (50) | 186 (43) | -14 | 0.239 |
Carbon dioxide production index (mL.min-1.m-2) | 115 (24) | 110 (24) | 120 (24) | 122 (24) | -12 | 0.002 |
Oxygen extraction ratio | 0.37 (0.13) | 0.36 (0.08) | 0.37 (11) | 0.44 (0.11) | -0.07 | 0.027 |
Central venous saturation (%) | 77 (9) | 77 (8) | 78 (8) | 74 (9) | 2 | 0.120 |
Arterial lactate (mmol/L) | 1.6 (0.9) | 1.5 (0.8) | 1.5 (0.8) | 1.6 (0.9) | -0.1 | 0.028 |