Acute lung injury in lung allografts

Background: Acute alveolar injury is a pathologic description of a nonspecific response of the lung to an acute injury. It has been our experience that acute alveolar injury may be seen in transbronchial biopsy and open lung biopsy specimens from patients who have successfully undergone lung transplantation. Because no studies of the clinical significance of acute alveolar injury in lung transplant recipients are available in the literature, we reviewed the impact of this pathologic finding in patients who underwent transplantation in the Toronto Lung Transplant Program. Methods: From November 1983 through December 1992, we retrospectively reviewed all transbronchial biopsies and open lung biopsies performed in lung transplant recipients. Results: Of the 137 transplantations performed (53 single and 84 double) acute alveolar injury was observed in 21 single (34 of 173 transbronchial biopsy and 10 of 24 open lung biopsy) and 22 double (38 of 415 transbronchial biopsy and 3 of 11 open lung biopsy) lung transplantations. We sought to explain this finding on the basis of the concurrent clinical scenario. Acute alveolar injury occurred most commonly in association with infection (52%) followed by postoperative period (19%) and acute (16%) rejection. Acute alveolar injury occurred as an isolated finding in 7% of patients. It occurred within the first 4 months after transplantation in 80% of cases. In 10 of 21 single lung transplantations and 12 of 22 double lung transplantations, acute alveolar injury was seen at least twice. However, no difference was found in mortality between such patients (6 of 10 single and 6 of 12 double lung transplantations) and patients with only one episode of acute alveolar injury. Conclusion: Acute alveolar injury is a relatively common finding in histologic specimens from patients with lung transplantation and is most commonly associated with infection.