DOES LUNG CONTUSION AFFECT BOTH THE TRAUMATIZED AND THE NONINJURED LUNG PARENCHYMA - A MORPHOLOGICAL AND MORPHOMETRIC STUDY IN THE PIG

Isolated unilateral lung contusion (LC) was induced in 12 pigs to dete rmine the pathophysiological role of LC in the high mortality after mu ltiple injury. The Horovitz quotient, pulmonary vascular resistance, m ean pulmonary artery pressure, mixed venous oxygen consumption, inspir atory pressure and compliance were significantly decreased in the LC g roup as compared to controls, The number of polymorphonuclear granuloc ytes, the microvascular permeabilty of albumine and the Wilhelmy balan ce as determined by bronchoalveolar lavage were significantly increase d after lung contusion. As indicators of a systemic reaction we found elevated plasma levels of the terminal complement complex and decrease d levels of the complement factor 3a after LC. The morphological asses sment revealed changes such as those encountered during the early phas e of adult respiratory distress syndrome, with granulocyte sticking, e ndothelial cell adhesion and transendothelial diapedesis. Morphometric analysis demonstrated a significant decrease in alveolar diameter in both the injured and the contralateral lung due to impaired surfactant surface activity. A distinct increase in septal diameter, related to edema and caused by increased microvascular permeability, was found in the injured lungs, These findings emphasize that LC leads to a genera lized impairment of the entire lung, which may lead to progressive lun g failure.