Bronchiolitis Obliterans After Lung Transplantation: Discussion

In: Bronchiolitis

5 Apr 2014

Bronchiolitis Obliterans After Lung Transplantation: DiscussionAs defined by the Working Formulation, BOS is a clinical diagnosis that refers to deterioration of graft function after lung transplantation secondary to a progressive airway disease that is otherwise unexplained by factors such as infection, acute rejection, or anastomotic complications; the term BO is reserved for a pathologically proved diagnosis. Pulmonary function testing is used as a sensitive and noninvasive screening procedure for BOS. Using criteria set by the ISHLT, the diagnosis of BOS is currently established on the basis of a >20% decline ofFEVi from baseline; as the earliest changes of BO consist of decreases in effort-independent flow rates, a decline in FEF25_75 to <70% has been proposed as a more sensitive criterion to define the onset of disease. In our study, 9 of the 11 (82%) patients with pathologically proved BO had BOS as defined by ISHLT criteria; 4 patients had had BOS diagnosed within 4 months of time of CT assessment. Of the two remaining patients with BO who did not fulfill ISHLT criteria for BOS, one developed an FEF25_75 <70% of baseline 10 days prior to CT assessment, and the second had no measurable signs of airway obstruction. COPD
In the lung transplant population, bronchoscopy with BAL and transbronchial biopsy specimens have been used as a sensitive and specific method for diagnosis of common pulmonary complications such as acute rejection and infection; however, detection of BO by transbronchial biopsy specimens may be problematic.2 Because of the patchy distribution of lesions of BO and the difficulty in obtaining adequate samples of alveolated lung containing bronchioles, the sensitivity of transbronchial biopsy specimens in detection of BO varies with the number of specimens taken per procedure. Since July 1992, our bronchoscopy protocol has consisted of 8 to 10 transbronchial biopsy specimens obtained from different lobes. In our institution, 70% of lung transplant recipients diagnosed as having BOS have had at least one abnormal transbronchial biopsy specimen documenting the presence of BO Although open lung biopsy remains a diagnostic option, it is seldom performed as the benefits of achieving a definite diagnosis of BO likely do not justify the attendant risks of the surgical procedure as well as the increased risk associated with future re transplantation, the current therapeutic option for patients with end-stage BO.

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