Complement activation following multiple injuries.

Complement activation was evaluated by assay of plasma C3dg and the terminal complement complex (TCC) in 19 patients with multiple injuries. In the nine patients with thoracic involvement, statistically significant increase of plasma TCC was found at first sampling (average 90 min post-trauma), and of C3dg after 24 hours. Such increase was not found in the ten patients without thoracic involvement. Heightened granulocyte elastase activity was found in bronchial lavage fluid 90 min after the trauma in three patients with thoracic injury. Pulmonary insufficiency (pO2/FiO2 less than 16 kPa on intermittent positive-pressure ventilation) arose in four patients. All four had raised plasma levels of TCC or C3dg on arrival at the hospital. Six patients with complement activation did not show pulmonary insufficiency. Although the series was relatively small, the results indicate that thoracic injury is particularly associated with complement activation, and that complement activation alone does not suffice to produce post-traumatic pulmonary insufficiency.