Ipsilateral Diaphragmatic Motion and Lung Function in Long-Term Pneumonectomy Patients

Background The physiologic advantages of preserving phrenic nerve integrity and normal diaphragmatic motion (DM) during the course of pnemonectomy are incompletely understood. This study was conducted to investigate potential benefits of this strategy on postoperative lung function. Methods Among 523 consecutive patients who underwent pneumonectomy for lung cancer between January 1992 and September 2001, 117 were alive at the time of study (March to December 2006) and thus had 5 yearsʹ minimum follow-up. Of those, 17 were excluded and 12 could not have magnetic resonance imaging (MRI), leaving 88 patients available for study. Diaphragmatic motion was assessed by MRI during deep breathing, and patients were classified as having normal and synchronous diaphragmatic motion (n = 44) or abnormal diaphragmatic motion (immobile or paradoxical, n = 44). These findings were correlated with expiratory volume measurements, gas exchange (arterial blood gases), and exercise tolerance (6-minute walk test). Results The mean follow-up time was 9.3 years. Patients with abnormal DM were younger than patients with normal DM and were more likely to have had a right or an extended pneumonectomy (p < 0.01). Despite comparable preoperative lung function, patients with abnormal DM had significantly worse postoperative lung volumes (forced expiratory voume in 1 second, forced vital capacity, lung diffusion capacity for carbon monoxide; p < 0.01) and exercise capacity (6-minute walk test, percent predicted, p < 0.05) than patients with normal DM. Conclusions Because the long-term effects of a paralyzed hemidiaphragm in pneumonectomy patients are characterized by significant alterations in lung function, all surgeons doing this type of work should take every precaution to avoid technical errors that could lead to phrenic nerve injury or interruption.