Comparison of Procedural Yield of Bronchoalveolar Lavage Using Three Different Techniques in Subjects Undergoing Flexible Bronchoscopy

Overview

Bronchoalveolar lavage (BAL) via flexible bronchoscopy is a method used to sample the cellular and microbiological components of the alveolar space. It is a procedure in which 2-3 measured aliquots of sterile normal saline are instilled after wedging the scope to the suitable segmental bronchus. BAL is performed from the segments/ lobes showing ground-glass opacities (GGO), tree-in-bud lesions or focal consolidations guided by HRCT. In diffuse lung involvement, BAL is performed either from RML or the lingula.\[3\] It is recovered through the bronchoscope via different suction methods so as to get a sample of epithelial lining fluid of small airways and alveoli. Either manual suction or wall suction can be used for aspiration of fluid during BAL. The fluid recovered is then sent for cytology and microbiology examination studies including AFB, MGIT, GeneXpert, Galactomannan, fungal cultures to diagnose various conditions like PAP, eosinophilic pneumonia, bacterial or fungal infections, specific forms of ILD. Three techniques have been described to perform BAL. To the best of our knowledge no previous study has compared the three methods of obtaining the BAL in the same cohort of subjects.The authors believe that the procedural yield of BAL will be best by manual suction using rubber tubing compared to manual suction without rubber tubing or wall suction. Herein, the investigators compare the three methods of obtaining BAL in subjects undergoing BAL for various respiratory diseases

Bronchoalveolar lavage (BAL) via flexible bronchoscopy is a method used to sample the cellular and microbiological components of the alveolar space. It is a procedure in which 2-3 measured aliquots of sterile normal saline are instilled after wedging the scope to the suitable segmental bronchus. BAL is performed from the segments/ lobes showing ground-glass opacities (GGO), tree-in-bud lesions or focal consolidations guided by HRCT. In diffuse lung involvement, BAL is performed either from RML or the lingula.\[3\] It is recovered through the bronchoscope via different suction methods so as to get a sample of epithelial lining fluid of small airways and alveoli. Either manual suction or wall suction can be used for aspiration of fluid during BAL. The fluid recovered is then sent for cytology and microbiology examination studies including AFB, MGIT, GeneXpert, Galactomannan, fungal cultures to diagnose various conditions like PAP, eosinophilic pneumonia, bacterial or fungal infections, specific forms of ILD Normal BAL cellular components are specified as: Alveolar macrophages (AM) 85%, Lymphocytes 5-15%, Neutrophils \<= 3%, eosinophils \<1%. The presence of squamous epithelial cells indicates contamination by oropharyngeal secretions. \[4\] Additionally, BAL can be a tool for pulmonary toilet in rare diseases such as pulmonary alveolar proteinosis by helping to remove the abnormal surfactant material that accumulates with this disease. Manual suction: It can be done using the same syringe used for instillation of the normal saline. At least 100 ml normal saline should be instilled while performing BAL and should not exceed 200 ml. According to the studies, Modification of the manual suctioning technique (by connecting small tubing attached to syringe) provides higher percentage of BAL fluid \[5\]. Wall suction: During suctioning the instilled fluid, negative pressure is applied using continuous wall suction. The pressure should be \<100mmHg or should be adjusted to prevent airway collapse.\[6\] In a study conducted by Aruna D. Herath\[7\], 73 pediatric patients were enrolled for a RCT undergoing flexible bronchoscopy and BAL. Two different suctioning techniques were compared for % of BAL fluid recovery. Sterile normal saline according to 1ml/kg was instilled and 100-150mmHg of negative pressure was applied for wall suction method. Thus it concluded that wall suction had better BAL fluid recovery than handheld syringe suction. Diagnostic yield was the same for both techniques. Luis M. Seijo\[8\], conducted a prospective randomized study of total 220 patients undergoing BAL. Study comparing manual and wall suction in performance of BAL resulted that manual aspiration is superior to wall suction yielding larger quantity of BAL. Additionally, extra tubing with 50 ml syringe was added in manual suction technique and 50mmHg negative pressure was used in wall suction method. A prospective clinical study of 66 patients by Naghmeh Radhakrishna\[9\], comparing techniques for optimal BAL performance used 100ml NS (with 4 aliquots) resulted in no significant difference between both techniques. Another study to compare two aspiration techniques of BAL in children was conducted by Christian Rosas-Salazar\[10\] on approximately 540 procedures. Their results suggested that handheld syringe suction provide higher % of fluid return when compared to continuous wall suction. K.S Woods\[11\], did a randomized, blinded prospective clinical trial on 18 dogs comparing manual and suction pump aspiration techniques for BAL. 35 ml syringe was used to instill 2ml/kg volumes per site for manual aspiration. Negative pressure of maximum 50mmHg was applied for SPA. Thus, concluded the study showing higher % of BALF return by SPA than manual suction with or without tubing. There was no significant difference in diagnostic yield. One more multicenter randomized study by Antoni Rosell\[12\] was conducted to recover BAL fluid comparing only syringe and syringe with attached plastic tube (40cm), for more fluid return. Thus, it resulted in 8% more fluid recovery, more yield and less complications with syringe with tubing suction technique. To the best of author's knowledge no previous study has compared the three methods of obtaining the BAL in the same cohort of subjects. The investigators believe that the procedural yield of BAL will be best by manual suction using rubber tubing compared to manual suction without rubber tubing or wall suction. Herein, the investigators compare the three methods of obtaining BAL in subjects undergoing BAL for various respiratory diseases. Study question: Is the procedural yield of BAL different between manual suction using rubber tubing compared to manual suction without rubber tubing or wall suction?