Use of the flow-volume loop in the diagnosis of bronchial stenosis after single lung transplantation

Bronchial complications, including stricture, stenosis, and/or anastomotic dehiscence, are a major cause of morbidity following single lung transplantation. This report describes a 19-year-old man with a diagnosis of end-stage pulmonary fibrosis secondary to prior chemotherapy for non-Hodgkins lymphoma who underwent single lung transplantation. The immunosuppressive regimen included cyclosporine, azathioprine, and methylprednisolone sodium succinate (Solu-Medrol) intravenously for six doses during the first 3 days postoperatively followed by oral prednisone. Sixteen weeks following transplantation, the patient complained of dyspnea. Spirometry revealed a decrease in FEF25-75 and the flow-volume curve demonstrated a bioconcave appearance. The flow-volume loop showed a relatively high initial flow phase occurring over the first 2 to 3 s followed by a low-flow phase. The expiratory phase also showed the same characteristics. Bronchoscopy revealed 75 percent stenosis of the bronchial lumen to the transplanted lung. A transbronchial biopsy specimen obtained at that time was consistent with acute rejection. The patient was treated with a methylprednisolone bolus. A repeated bronchoscopy showed the persistence of stenosis distal to the anastomosis. The patient underwent several bronchoplastic balloon dilatations without complete resolution of the stenosis and a stainless steel mesh stent was placed. Repeated spirometry showed marked improvement of the FEF25-75 and normalization of the flow-volume loop. We conclude that the flow-volume loop curve is a noninvasive procedure that may help monitor the patency of the bronchial anastomoses following single lung transplantation.