Effect of Lung Contusion on Pulmonary

slope was less pronounced. In both groups shunt fraction did not rise above 0.31. In the nonreactors, PVRI remained normal while shunt fraction increased with the extent of injury (r = 0.95). These results indicate that pulmonary vasoconstriction often occurs after pulmonary contusion. The vasoconstriction most probably represents a compensatory mechanism to limit perfusion of traumatized parenchyma, thereby minimizing increases in shunt fraction. Some patients (nonreactors) not demonstrating this response have unchecked increases in shunt fraction. This insight into the hemodynamic sequelae of pulmonary contusions may enhance our ability to provide optimal care for patients suffering from this injury. (Ann Thoruc Surg 1992;52:52-8)