In multiple trauma patients with lung contusion, pulmonary complications have been reported that were attributed to intramedullary stabilization of the femur. The reaming procedure of the medullary canal is thought to play a major role. We investigated whether different types of reamers might exert different amounts of fat mobilization into the vascular system and different degrees of pulmonary dysfunction. Adult female Merino sheep were submitted to hemorrhagic shock (2 h, 50 mm Hg) and a unilateral lung contusion; in addition, a lung lymph fistula was created. Pulmonary capillary permeability, central venous triglyceride levels, 11-dehydro-thromboxane B2 (dh-TXB2) levels, and pulmonary artery pressure were determined. After recovery, animals were randomly assigned to intramedullary femoral nailing using several types of reamers: group A, AO reamer (n = 8); group B, Biomet reamer (n = 7); group H, Howmedica reamer (n = 6); group C, controls, no reaming (n = 4). Intramedullary reaming caused a significant (p < 0.05) increase in pulmonary artery pressure in groups A and B; dh-TXB2 levels increased in all groups. Statistically significant (p < 0.05) pulmonary capillary permeability damage was measured in group A only. Intramedullary femoral nailing can cause transient pulmonary hemodynamic and mediator effects as well as increased pulmonary capillary permeability. In the present study, this effect was evident in group A reamer systems only, which may be due to reamer construction.