UTILITY OF TRANSBRONCHIAL BIOPSY IN PATIENTS WITH ACUTE RESPIRATORY-FAILURE - A POSTMORTEM STUDY

Study objective: To determine the diagnostic yield of histologic speci mens obtained by postmortem transbronchial biopsy (TBB) in patients wi th acute respiratory failure requiring mechanical ventilation. Design: Standard postmortem histologic examination of lung tissue specimens. Setting: An urban university-affiliated hospital. Patients or particip ants: Thirty patients with diffuse pulmonary infiltrates and acute res piratory failure, who underwent postmortem examination. Interventions: Following removal of the lungs from the thorax. TBBs were obtained fr om the lower lobe of each deflated lung and comparison was made to a 1 -cm(3) tissue block obtained from the ipsilateral lower lobe. Measurem ents and results: Standard postmortem histologic examination provided a specific diagnosis in 85% of the 60 lungs examined, and histologic e vidence of acute pneumonia was present in 30% of the lungs. The overal l yield of TBB was 48% for establishing a specific histologic diagnosi s and 15% for the diagnosis of acute pneumonia, Using standard postmor tem histologic examination as the gold standard, the sensitivity and s pecificity of TBB for making a specific diagnosis were 57% and 100% re spectively, with corresponding positive and negative predictive values of 100% and 29%. for the histologic diagnosis of acute pneumonia, the sensitivity of TBB was 50%, the specificity was 100%, and the positiv e and negative predictive values were 100% and 82%, respectively. The kappa statistic for the agreement between the two diagnostic methods w as 0.28 for establishing a specific diagnosis and 0.58 for the diagnos is of acute pneumonia. Obtaining 12 TBBs rather than six TBBs did not increase the diagnostic yield for TBB. Conclusions: These findings sug gest poor overall agreement between standard postmortem histologic exa mination and TBB specimens. Although not performed in a clinical setti ng, this postmortem investigation suggests that TBB may be of limited value in mechanically ventilated patients with acute respiratory failu re because of its low sensitivity.