Intramedullary femoral nailing in sheep: does severe injury predispose to pulmonary dysfunction?

OBJECTIVE

To find out if intramedullary nailing affects lung function and microvascular permeability whether or not the lung is already injured; if so whether a different method of fixation would diminish the effect; and are the pathogenetic changes related to mechanisms known to precipitate adult respiratory distress syndrome?

DESIGN

Experimental study.

SETTING

University hospital, Germany.

MATERIAL: 29 Adult female merino sheep.

INTERVENTIONS: Chronic lung lymph fistulas were created. Two of the three groups (1 and 3) underwent right sided lung contusion and haemorrhage to a mean blood pressure of 50 mm Hg for 2 hours. On day 3 groups 1 and 2 underwent intramedullary nailing, and group 3 had external fixators applied.

MAIN OUTCOME MEASURES: Pulmonary arterial pressure, concentrations of triglycerides, chemiluminescence of isolated polymorphonuclear leucocytes (PMN), lymph flow, microvascular pressure, filtration coefficient, and permeability.

RESULTS

Intramedullary nailing caused a transient significant increase in pulmonary arterial pressure and triglycerides in groups 1 and 2. Chemiluminescence of isolated PMN decreased in group 1 and increased in group 2. Lymph flow increased 2.5 times in group 1 while microvascular pressure decreased; in group 2 the increase was less but microvascular pressure increased. Filtration coefficient in group 1 was five times that of group 2 and there was a twofold increase in permeability. There were no changes in group 3.

CONCLUSION

Intramedullary nailing causes additional damage to lungs after lung damage and haemorrhagic shock in sheep. This can be avoided if (in the presence of additional injuries) alternative methods are used.