Ventilation-perfusion relationships following experimental pulmonary contusion

Ventilation-perfusion changes after right-sided pulmonary contusion (PC) in swine were investigated by means of the multiple inert gas elimination technique (MIGET). Anesthetized swine (injury, n = 8; control, n = 6) sustained a right-chest PC by a captive-bolt apparatus. This was followed by a 12-ml/kg hemorrhage, resuscitation, and reinfusion of shed blood. MIGET and thoracic computed tomography (CT) were performed before and 6 h after injury. Three-dimensional CT scan reconstruction enabled determination of the combined fractional volume of poorly aerated and non-aerated lung tissue (VOL), and the mean gray-scale density (MGSD). Six hours after PC in injured animals, PaO2 decreased from 234.9 ± 5.1 to 113.9 ± 13.0 mmHg. Shunt (QS) increased (2.7 ± 0.4 to 12.3 ± 2.2%) at the expense of blood flow to normal ventilation/perfusion compartments (97.1 ± 0.4 to 87.4 ± 2.2%). Dead space ventilation (VD/VT) increased (58.7 ± 1.7% to 67.2 ± 1.2%). MGSD increased (−696.7 ± 6.1 to −565.0 ± 24.3 Hounsfield units), ...