Bronchoalveolar lavage in interstitial lung diseases: does the recovery rate affect the results?

Bronchoalveolar lavage (BAL) is an established diagnostic tool in interstitial lung diseases. BAL frequently yields findings of diagnostic value and at times even confirmatory diagnostic results.

The present study has been designed to investigate whether the recovery rate affects BAL results relative to the instilled volume.

Six hundred and eighteen patients with the following diagnoses were included into the study: 236 with sarcoidosis, 85 with idiopathic pulmonary fibrosis, 83 with cryptogenic organizing pneumonitis, 64 with connective tissue disease affecting the lungs, 54 with respiratory bronchiolitis with interstitial lung disease, 51 with extrinsic allergic alveolitis and 45 control patients. BAL was performed during flexible bronchoscopy with an irrigation volume of 100 ml 0.9% saline solution in 5 aliquots of 20 ml each. Only patients with a recovery of at least 30 ml were evaluated. Initially, the entire patient population was analysed, followed by an analysis within the different diagnostic groups and a comparison between patients with a high (>50 ml) and low (< or =50 ml) recovery rate.

The recovery rate varied between the diagnostic groups (p < 0.001) and was negatively correlated with age (r = -0.21, p < 0.001) and smoking history (r = -0.11, p < 0.035). There were no correlations with inspiratory vital capacity (%pred.; p = 0.26) and forced expiratory volume in 1 s (%pred.; p = 0.15), but a positive correlation with the index (forced expiratory volume in 1 s/inspiratory vital capacity) x 100 (r = 0.23, p < 0.001). The cellular and non-cellular constituents of BAL were not affected by the recovery: cells/millilitre BAL (p = 0.71), relative proportion of macrophages (p = 0.92), lymphocytes (0 = 0.33), neutrophils (p = 0.14) and eosinophils (p = 0.11), albumin concentration (p = 0.13), and proportion of albumin in total protein (p = 0.06). The same applied for the lymphocyte surface markers CD4 (p = 0.72) and CD8 (p = 0.53). In the group with a high recovery rate, patients with sarcoidosis had a lower proportion of eosinophils (p = 0.04) and patients with cryptogenic organizing pneumonitis a higher concentration of albumin (p = 0.02) and lymphocytes (p = 0.007). Otherwise, no further differences were detected.

The recovery rate hardly affected the cellular and non-cellular constituents of BAL at a lower limit of 30% of the instilled volume.