PERSISTENT HYPERINFLATION AFTER HEART-LUNG TRANSPLANTATION FOR CYSTIC-FIBROSIS

We have measured static lung volumes after heart-lung transplantation (HLT) in seven patients with cystic fibrosis (CF) (Group 1), three pat ients with chronic hyperinflation due to diseases other than CF (Group 2), and six patients with primary pulmonary hypertension (PPH) (Group 3). Total lung capacity was within normal limits at 1 yr after surger y in all patients. Similarly, FRC was within the normal range in Group s 2 and 3. On the other hand, patients with CF showed a persistent inc rease in FRC; at 1 yr after HLT, FRC averaged 4.13 +/- 0.52 L compared with a predicted value of 3.20 +/- 0.23 L (p < 0.01). The postoperati ve static pressure-volume curve of the lung in the patients with CF wa s superimposed on the predicted one, suggesting that the increased FRC originated in the chest wall. Additional studies with computerized to mographic scans demonstrated that the rib cage anteroposterior diamete r at FRC averaged 12.1 +/- 1.6 cm in patients with CF, 9.5 +/- 1.2 cm in patients with PPH, and 9.4 +/- 0.7 cm in a group of healthy subject s matched with the patients with CF (p < 0.01). We conclude that after HLT, patients with CF show persistent hyperinflation due to rib cage expansion along the anteroposterior dimension. This shape change may r epresent a structural adaptation that occurs in response to chronic pu lmonary hyperinflation acquired during rib cage growth.