Diagnostic properties of transbronchial biopsy in lung transplant recipients who require mechanical ventilation. (2003)

Comments: This retrospective study was designed to determine the sensitivity, specificity, and positive and negative predictive values of bronchoscopic lung biopsy (BLB) compared with surgical lung biopsy (SLB). The study group included 41 mechanically ventilated patients with respiratory failure in whom 42 BLBs were followed within a 10-day period by SLB. There were 16 men and 25 women with a mean age of 42.5 ± 12.5 years. Indications for transplantation included emphysema (13 of 41), cystic fibrosis (8 of 41), Eisenmenger's syndrome (7 of 41), idiopathic pulmonary fibrosis (4 of 41), primary pulmonary hypertension (3 of 41), bronchiectasis (3 of 41), and isolated cases of lymphangioleiomyomatosis, crest syndrome and sarcoidosis. Fifteen patients underwent double-lung transplantation, whereas 20 patients underwent single-lung transplantation, and 6 patients underwent heart-lung transplantation. The following were the criteria for inclusion in the study: 1.) mechanical ventilation at the time of BLB, 2.) progressive radiographic abnormalities or clinical deterioration, and 3.) SLB performed within 10 days of BLB. The authors reviewed the indication for diagnostic intervention, radiographic appearance at the time of BLB, type of SLB (open vs. video-assisted thoracoscopic), complications of BLB or SLB, histopathologic results of BLB and SLB specimens, and changes in management after performing SLB. All lung transplant recipients received maintenance immunosuppression with tacrolimus or cyclosporine, prednisone, and either azathioprine or mycophenolate mofetil. Acute rejection and obliterative bronchiolitis were treated with methylprednisolone or cytolytic therapy that included rabbit antithymocyte globulin or OKT3. BLB was performed under general anesthesia in the operating room or in the bronchoscopy suite. Six 2-mm BLB specimens were obtained from the area of greatest radiographic abnormality, or from at least three basilar segments of the lower lobe of the allograft in the absence of radiographic opacities. SLB was performed when there was persistent radiographic or clinical compromise. SLB included either the open approach or a video-assisted thoracoscopic approach. The sensitivity, specificity, and positive and negative predictive values of BLB for all episodes of acute rejection and for significant episodes of acute cellular rejection were 53% and 36%, 92% and 94%, 94% and 90%, 44% and 50% respectively. A significantly higher histologic grade was noted on SLB compared with BLB specimens obtained within a 10-day period (2.39 ± 1.02 vs 0.97 ± 0.11, p ≤ 0.0001). Performing SLB in this setting increased histopathologic diagnoses by 33% and resulted in treatment changes in 15 of 41 patients (37%). Based on these findings, the authors concluded that BLB has low sensitivity, high specificity, and a high positive predictive value for diagnosing acute rejection. They also found a significant tendency for BLB to underestimate the presence and severity of clinically significant grades of rejection while simultaneously overestimating the presence of clinically insignificant rejection. The authors infer that adding SLB is valuable in lung transplant recipients with respiratory failure who require mechanical ventilation. The main problem with BLB is that it obtains smaller fragments of lung tissue, in contrast to SLB, which obtains ample specimen for pathologic analysis. However, few patients require SLB for the detection of allograft rejection and opportunistic infections, because these can be diagnosed in most patients by the use of BAL and BLB. The publication by Burns et al. looks at the special group of lung transplant recipients—namely, those who develop respiratory failure necessitating mechanical ventilation. Some studies have reported that SLB is helpful in lung transplant recipients when performed during the late postoperative period because the procedure resulted in new diagnoses in as many as 33% of patients. The results by Burns et al. show that SLB in this group of patients increased histopathologic diagnoses by 33% and resulted in changes in treatment of 37% of patients.