Since first introduced in the early 1970s, flexible bronchoscopy has allowed clinicians to perform BAL on distal regions of the lung previously inaccessible.

Indications for rigid or flexible bronchoscopy are numerous.¹ For example, bronchoscopy may be used to investigate cough or hemoptysis; to seek an explanation for localized wheezing and bronchial obstruction; to locate or remove foreign bodies; to inspect the tracheobrachial tree; or to explore the severity, cause, and extent of inflammation. Preoperatively, assessment of lung abscess, carcinoma, tuberculosis, or bronchiectasis can be performed using bronchoscopy to direct the surgeon’s efforts. Other disorders where direct visualization or sampling of fluid or tissue may be helpful include suspicious or malignant cells in sputum, infiltrates of unknown etiology, and diaphragmatic paralysis.

Rigid bronchoscopy is primarily used in cases of massive hemoptysis, for biopsy of vascular tumors where excessive bleeding is suspected (bronchial adenoma), to resect tumors or granulation tissue, and for foreign-body extraction. Because of its design, the rigid bronchoscope’s use is limited to the larger, more proximal airways. About 40 years ago, Ikeda invented the flexible bronchofiberscope, which allowed positioning in (and image collection from) the distal airways. This extended the anatomic range of visualization from the larger proximal airways to the smaller distal airways. With the introduction of the fiber-optic bronchoscope, noninvasive direct visualization of and specimen sampling from the lung and surrounding tissues became reality. This innovation greatly extended the utility of bronchoscopy; through the application of newer technologies, the fiber-optic bronchoscope emerged as a safe, widely used instrument for:

• visualizing the proximal and distal airways,
• controlling alveolar hemorrhage,
• sampling fluids associated with infiltrative and other processes,
• collecting tissue using small biopsy forceps,
• identifying peripheral tumors using brushings or biopsies,
• exploring lesions in the upper lobe,
• investigating small hilar lesions,
• assessing mechanical difficulties with respiration,
• inspecting the nasopharynx and larynx, and
• removing foreign bodies (with some limitations).

Fiber-optic bronchoscopes are produced in a variety of sizes and configurations, with and without video capability, thereby extending the utility of bronchoscopy to patients from infancy through adulthood and providing sampling capabilities to investigate the inflammatory/immune-cell milieu of the human lung.

Fiber-optic bronchoscopy is an extremely safe procedure when certain precautions are observed.² Studies³ have reported mortality rates of 0.01% and a major complication rate of 0.08% in 24,521 procedures, while a separate study⁴ reports 0.02% mortality and a 0.3% major complication rate in a series of 48,000 procedures. A more recent investigation⁵ representing over 4,000 cases, with 2,000 lavages and 173 transbronchial biopsies, showed no deaths, with major and minor complication rates of 0.5% and 0.9%, respectively.

Lavage
Bronchoalveolar lavage (BAL) must be distinguished from bronchial lavage. In the latter, saline is instilled into the large airways or bronchial tubes and then aspirated for fluid analysis. During bronchial lavage, the regions of lung being washed are the larger airways; such sampling is used primarily to detect cytological abnormalities such as cancer or to identify infectious pathogens. In contrast, during BAL, the bronchoscope is directed into a smaller airway to minimize sampling from the large airways. By concentrating on the smaller airways and the distal alveolar surfaces, BAL gains access to different components of lung biology. BAL may be focused on specific regions of the lung, and multiple lavages may be performed during the same procedure, if desired, with each lavage sampling upwards of 3% of the lung’s total alveolar volume.

BAL has become a widely used diagnostic technique for a broad array of patients. BAL reveals specific information in disorders such as pulmonary alveolar proteinosis, Langerhans-cell histiocytosis, alveolar hemorrhage, malignant infiltration, hypersensitivity pneumonitis, pneumoconiosis, other infiltrative processes, sarcoidosis, asthma, chronic obstructive pulmonary disease (COPD), and exposure to dusts and chemicals. For these applications, BAL can often replace open lung biopsy.

BAL is a minimally invasive, first-line examination of the lung parenchyma. Cytology, Gram staining, and culturing can be performed on the fluids collected. Many other biomarkers can be analyzed from BAL fluids, and this can assist the clinician in establishing a diagnosis, in refining differential diagnosis, and in the clinical management of the patient.

Preparation, Recovery, and Expectations
Bronchoscopy is possible in patients who are very ill, even if they are intubated or in intensive care. The procedure can be done in fully awake individuals with only topical anesthesia of the airways using aerosolized lidocaine. Most bronchoscopies, however, are done under conscious-sedation anesthesia, as outpatient procedures. To reduce aspiration risk, bronchoscopies are done after the patient fasts overnight; ideally, the procedure is done after other medical problems, such as COPD, have been stabilized. If biopsies are anticipated, coagulation parameters should be optimized. Significant hemorrhage is an uncommon complication of bronchoscopy that is generally limited to biopsied patients in whom bleeding has existed prior to surgery. Similarly, pneumothorax is a complication of biopsied cases. The risks of BAL are defined by the bronchoscopy procedure itself, since BAL does not add any significant risk to the procedure.

Standard recovery procedures from conscious-sedation anesthesia are followed, when applicable, and most complications are recognized during the immediate preoperative period. The most frequently recognized risks include transient hypoxemia, cough, and dyspnea. Fever within 24 hours may be seen in as many as 20% of patients. It is standard to obtain a portable chest radiograph after bronchoscopy (to detect pneumothorax) only when biopsies have been obtained. Nearly all patients are able to go home following outpatient bronchoscopy.

BAL Techniques
BAL is a simple addition to flexible bronchoscopy. After inspection of the airways, and before any brushings or biopsies are taken, the bronchoscope is wedged into a smaller airway (a fourth-division or fifth-division subsegment of one of the lobar bronchi). Saline, in aliquots of 50 mL to 60 mL, is delivered via syringe into the distal airway through the suction channel of the bronchoscope. It is then quickly aspirated, under gentle suction, into a collection trap or syringe. Care and skill are required to retrieve a good percentage of the 100 to 200 mL given as the total lavage. Excessive suction will collapse the airway, occluding the suction channel and diminishing fluid recovery.

The single-cycle lavage technique consists of one instillation of about 100 mL to 120 mL of normal saline through a bronchoscope and into an identified lung segment. This is followed by immediate withdrawal of the fluid in a sequential fashion. In animal and human studies,^6,7 this technique has been demonstrated as efficacious for fluid collection where knowledge of the makeup of the epithelial lining fluid is deemed important. Further, the rapid, single-cycle wash facilitates the use of urea as a marker of dilution, thereby allowing the calculation of solute concentrations in the epithelial lining fluid. There is some evidence that fluid yield is enhanced by using the single-cycle technique for collection of cells, bacteria, and other evidence of infectious processes.

BAL is distinguished from segmental or whole lung lavage (WLL), a therapeutic procedure most often employed in pulmonary alveolar proteinosis to wash out the proteinaceous material occluding the airspaces. In WLL, both lungs are separately intubated under general anesthesia and one lung at a time is completely and repeatedly filled to total lung capacity with saline, then gravity drained, rinsing the lung free of occlusive material. In WLL, the primary risk of the procedure is that of drowning both lungs simultaneously, causing secondary hypoxemia. WLL is a procedure done only in a few tertiary care centers.

Summary
As a research tool, BAL has been used to characterize the effectiveness of intravenous drug delivery to the lungs and to improve understanding of lung biology in the distal lung. It is able to collect inflammatory cells and mediators for analysis. In that way, BAL has been invaluable to the understanding of disease states such as sarcoidosis and pulmonary fibrosis. For the physician, BAL has clinical utility as well. It allows the safe sampling of the distal lung for specific pathogens (for example, Mycobacterium tuberculosis) in patients unable to expectorate diagnostic sputum. BAL has become a simple, yet important, tool in the hands of chest physicians and scientists.

James Stocks, MD, is professor of pulmonary and critical care medicine, internal medicine, University of Texas Health Center at Tyler; James Williams, PhD, is associate professor, exercise physiology and physiology; and Rick Carter, PhD, MBA, is professor and chair, department of health, exercise, and sport sciences and physiology, Texas Tech University, Lubbock.

References
1. American Thoracic Society. Clinical role of bronchoalveolar lavage in adults with pulmonary disease. Am J Respir Crit Care Med. 1990;142:481-486.
2. Zavala D. Diagnostic fiberoptic bronchoscopy: techniques and results of biopsy in 600 patients. Chest. 1975;68:12-9.
3. Credle W, Smiddy J, Elliott R. Complication of fiberoptic bronchoscopy. Am Rev Respir Dis. 1974;109:67-72.
4. Suratt P, Smiddy J, Gruber B. Deaths and complications associated with fiberoptic bronchoscopy. Chest. 1976;69:747-751.
5. Pue C, Pacht E. Complications of fiberoptic bronchoscopy at a university hospital. Chest. 1995;107:430-432.
6. Peterson BT, Idell S, MacArthur C, Gray LD, Cohen AB. A modified bronchoalveolar lavage procedure that allows measurement of lung epithelial lining fluid volume. Am Rev Respir Dis. 1990;141:314-320.
7. Griffith D, Blevins W, Girard B, Carter R, Kurdowska A. Single-cycle lavage provides estimates of solute concentrations in the epithelial lining fluid of specific regions of the lungs. Eur Respir J. 2004;24(suppl 48):10s.