Division of the pulmonary ligament after upper lobectomy is less effective for the obliteration of dead space than leaving it intact.

PURPOSE: To investigate whether division of the pulmonary ligament after upper lobectomy obliterates dead space. METHODS: Thirty-five patients scheduled to undergo upper lobectomy (23 right, 12 left) were randomly assigned to two groups, according to whether the inferior pulmonary ligament was divided (11 right, 12 left) or preserved (6 right, 6 left). To assess upward movement of the nonoperated lobes, plain chest X-ray films (posterior-anterior) were done at end-inspiration preoperatively and 1 month postoperatively, and the ratio of dead space in the longitudinal axis was measured. To assess the change in the angle of the main bronchus, chest X-ray tomography films were done preoperatively and 1 month postoperatively. The angles formed by the main bronchus and the truncus intermedius on the right side, and by the main bronchus and the lower bronchus on the left side, were measured, and the postoperative changes were calculated. RESULTS: The dead space ratio did not differ significantly between the divided group and the preserved group (3.5% vs 5.5%) or between sides. The change in the angle of the main bronchus did not differ significantly between the two groups on either the right (36.4 degrees vs 36.3 degrees) or the left side (72.5 degrees vs 60.0 degrees). CONCLUSION: Division of the pulmonary ligament after upper lobectomy is less effective for the obliteration of dead space than leaving it intact.