Multiply injured patients (an Injury Severity Score of 17 points or more) who were admitted to one of two level-I regional trauma centers between 1983 and 1994 because of a fracture of the femoral shaft with a thoracic injury (an Abbreviated Injury Scale score of 2 points or more) or without a thoracic injury were studied retrospectively. The patient populations and the protocols for the treatment of trauma were similar at the two centers; however, the centers differed with regard to the technique that was used for acute stabilization of the fracture of the femoral shaft. At Center I intramedullary nailing with reaming was used in 217 (95 per cent) of the 229 patients, whereas at Center II a plate was used in 206 (92 per cent) of the 224 patients. This difference was used to investigate the effect of acute femoral reaming on the occurrence of adult respiratory distress syndrome in multiply injured patients who had a chest injury.Three groups of patients were evaluated: those who had both a fracture of the femur and a thoracic injury, those who had a fracture of the femur but no thoracic injury, and those who had a thoracic injury without a fracture of the femur or the tibia. The third group was studied at each center to determine if there was a difference between the institutions with regard to the rate of adult respiratory distress syndrome. Patients who had diabetes, chronic obstructive pulmonary disease, asthma, hepatic or renal failure, or an immunosuppressive condition were excluded from the study.The records were abstracted to determine the Injury Severity Score, Abbreviated Injury Scale score, and Glasgow Coma Score for each patient. Requirements for fluid resuscitation were calculated for the first twenty-four hours; these included the number of units of packed red blood cells, fresh-frozen plasma, and platelets that were transfused and the volume of crystalloid that was used. The duration of intubation, the duration of hospitalization, and the occurence of adverse outcomes (death, multiple organ failure, adult respiratory distress syndrome, pneumonia, and pulmonary embolism) were determined for each patient. The groups of patients were analyzed as a whole and then were stratified into subgroups (according to whether or not they had a thoracic injury and whether the Injury Severity Score was less than 30 points or 30 points or more) to determine if the type of fixation of the femoral fracture affected the rate of adult respiratory distress syndrome or mortality. Logistic regression models were used to analyze the data.The over-all occurrence of adult respiratory distress syndrome in the 453 patients who had a femoral fracture was only 2 per cent (ten patients). The rates of adult respiratory distress syndrome for the patients who had a thoracic injury but no femoral fracture (eight [6 per cent] of 129 patients at Center I, compared with ten [8 per cent] of 125 patients at Center II) did not differ between centers, suggesting that the institutions were comparable in their treatment of multiply injured patients. The occurrence of adult respiratory distress syndrome in the patients who had a femoral fracture without a thoracic injury did not differ substantially according to whether the fracture had been treated with a nail (118 patients) or a plate (114 patients). Likewise, the frequency of adult respiratory distress syndrome, pneumonia, pulmonary embolism, failure of multiple organs, or death for the patients who had a femoral fracture and a thoracic injury was similar regardless of whether nailing with reaming (117 patients) or a plate (104 patients) had been used.The use of intramedullary nailing with reaming for acute stabilization of fractures of the femur in multiply injured patients who have a thoracic injury without a major comorbid disease does not appear to increase the occurrence of adult respiratory distress syndrome, pulmonary embolism, failure of multiple organs, pneumonia, or death.