THE EFFECTS OF FEMORAL INTRAMEDULLARY REAMING ON PULMONARY-FUNCTION IN A SHEEP LUNG MODEL

Two methods of intramedullary fixation of fractures of the middle of t he femoral shaft were evaluated in a sheep model to determine the effe ct of femoral reaming on pulmonary function. The effect of a modified reamer was also studied. A second experiment with the same model was p erformed to evaluate the relationship between embolization and pulmona ry dysfunction. This Experiment involved two groups of sheep - those w ith normal lungs and those with contused lungs - divided into subgroup s - those that had nailing with reaming and those that had nailing wit hout seaming, Intracardiac ultrasound was used to measure the magnitud e and duration of transvenous particulate embolization during the oper ations, Both experiments involved hemodynamic monitoring during and af ter the nailing. The pulmonary tissue was examined histologically afte r the animals were killed. The hemodynamic monitoring revealed only a transient increase in pulmonary vascular resistance in the animals tha t had femoral nailing with reaming in both experiments, The modified r eamer had no effect on the pulmonary response. Histological analysis o f pulmonary tissue demonstrated a significant increase in the number o f fat emboli in both the animals that had nailing with reaming and the animals that had nailing without reaming compared with the control an imals. Intravascular ultrasound revealed that tile operative maneuver associated with the greatest number of emboli was opening of the intra medullary canal with the awl. The first two passes of the reamer produ ced more emboli and embolism of longer duration than did the later pas ses. Pulmonary contusion did not increase the risk of pulmonary dysfun ction due to intramedullary nailing in this model. CLINICAL RELEVANCE: Pulmonary dysfunction as a result of intramedullary nailing was minim um in our fracture model. There was no significant difference, between the animals that had reaming and those that did not have reaming, wit h regard to the adverse effects on pulmonary function, Beaming had a m inor transient effect on pulmonary vascular resistance that was not se en in the animals that did not have reaming, The minor pulmonary effec ts in the two groups were not worsened by the presence of a pulmonary contusion. We concluded that, with regard to their effects on pulmonar y function, there was no distinct advantage either to nailing with rea ming or to nailing without reaming for fractures of the femoral shaft.