Bronchoalveolar Lavage


Article Author:
Pujan Patel
Marsha Antoine


Article Editor:
Saad Ullah


Editors In Chief:
Yvonne Carter
Jason Wallen


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Kyle Blair
Trevor Nezwek
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Daniyal Ameen
Altif Muneeb
Beenish Sohail
Nazia Sadiq
Hajira Basit
Phillip Hynes
Komal Shaheen
Sandeep Sekhon


Updated:
6/28/2019 8:31:51 PM

Introduction

Bronchoalveolar Lavage or BAL is a minimally invasive procedure that involves instillation of sterile normal saline into a subsegment of the lung, followed by suction and collection of the instillation for analysis. This procedure is typically facilitated by the introduction of a flexible bronchoscope into a sub-segment of the lung. The procedure was popularized in 1974 by the work of American physicians, Reynolds and Newball, in Maryland. Today, it serves predominantly as a diagnostic tool for the evaluation of lower respiratory tract pathology and in some uncommon conditions, it also has therapeutic utility.[1][2]

Etiology

A significant portion of pathological disease within the lungs occurs at the alveolar level. BAL allows for the collection of the alveolar milieu and further analysis of its composition. Common scenarios for the use of BAL include work up for opportunistic and atypical respiratory infections in immunocompromised patients, unexplained radiographic pulmonary infiltrates or hypoxemia. BAL can also provide clues to support the diagnosis of some noninfectious conditions such as Diffuse Alveolar Hemorrhage (DAH), Pulmonary Alveolar Proteinosis (PAP), Eosinophilic Pneumonia, Hypersensitivity Pneumonitis (HP), Interstitial Lung Diseases (ILDs), chronic berylliosis, the presence of malignant cells and Asbestos exposure.

Pathophysiology

Although societies such as American Thoracic Society and British Thoracic Society have published guidelines on the performance of BAL, there remains some variability in its performance. BAL is typically performed after introduction of the bronchoscope into the tracheobronchial tree and inspection of the airways but before any biopsies or brushings are collected. This minimizes the potential introduction of bronchial wall debris and additional red blood cells (RBCs) into the most distal airways, which could alter the composition of the lavage fluid. The outer diameter of adult flexible bronchoscope tips range between approximately 3mm-6mm, and the scope is guided into the subsegment of the lung that is to undergo BAL and advanced until the tip is wedged into a bronchiole.

Depending on local practice, anywhere from between 20 - 60 ml of room temperature, sterile normal saline is injected via handheld syringe and then gradually withdrawn back into the syringe. This is repeated 3-5 times, and a total of up to 300 ml is instilled. If only 5% of each aliquot injected returns - indicating that most of the injected fluid is being retained, the procedure should be aborted. A return sample yield of 30% or more of the instillate is considered an adequate return, of which at least 10 ml - 20 ml is required for cellular and infectious workup.

If a localized disease process predominates, usually identified on radiological imaging (e.g., hence a Chest X-ray or Computed Tomography (CT) of the Chest), then the bronchoscope is guided to that specific region and wedged into the subsegment with visualization of the distal airway ideally in the center of the image. If diffuse, (the heterogeneous disease is present on imaging), the most commonly preferred locations for lavage would be the right middle lobe or lingula. As bronchoscopy is usually performed with the patient lying supine, the anteriorly projected location of these segments allows gravity to assist with maximal BAL. Hence we prefer these sites. If these segments are not accessible, the superior or anterior segment of either lower lobe may also be used. In theory, this process enables lavage of up to 1 million alveoli.[3][4]

Histopathology

Even though the collection of BAL samples is not standardized, experts suggest following a protocol to minimize contamination and artifacts. The recovered lavage fluid should be pooled, mixed, and the volume recorded. The fluid should be sent to the laboratory while stored on ice if the transportation is going to be delayed by more than 1 hour. Studies show that cells in BAL fluid can remain viable for 4 hours at room temperature. The fluid is usually analyzed for white and red cells. To distinguish immature macrophages from large lymphocytes, esterase staining is employed. Other stains may evaluate for the presence of iron, malignant cells, inorganic dust, and microorganism. In general, if the BAL specimen contain less than 2 million total cells or has fewer than ten alveolar macrophages per high-power field, or contains a high number of red cells (due to trauma) or there are degenerative changes, the specimen should not be relied upon to make any valid diagnosis. Of note, the average number of cells recovered from BAL fluid in healthy nonsmoking adults varies from 100-150,000/ml. Smoking increases the number of cells by 4-6 fold, of which most are macrophages.[5][6]

Toxicokinetics

Similar to any flexible bronchoscopy, awareness of toxicity and side effects of medications given for conscious sedation (e.g. midazolam, propofol, fentanyl, etc.) and cough suppression (topical lidocaine) is necessary.

History and Physical

When taking the history, ensure that there are no contraindications to bronchoscopy for the purpose of BAL, such as myocardial infarction within the past four weeks or unstable angina, hemodynamic instability, uncontrolled arrhythmias and refractory hypoxemia.

Taking note of smoking status and exposure history is also important to give the substantial effect smoking has on the cellular composition of BAL, namely many more neutrophils and macrophages than in nonsmokers.

Evaluation

The paucity of good evidence to support specific values for a normal BAL, leaves us to pay attention to the specific cell line cut offs that certain support diagnoses such as:

  • Increased Neutrophils (>5%)
    • Idiopathic Pulmonary Fibrosis (IPF), Acute Respiratory Distress Syndrome (ARDS), infection, connective tissue disorders.
  • Eosinophilia
    • >25%: suggesting eosinophilic lung diseases such as acute eosinophilic pneumonia, chronic eosinophilic pneumonia, and Churg-Strauss syndrome
  • Lymphocytosis
    • > 50% : Hypersensitivity Pneumonitis
    • When greater than or equal to 15% Lymphocytes are present, CD4/CD8 ratios can be assessed.
      • Elevated CD4/CD8: hypersensitivity pneumonitis (chronic or smoker), sarcoidosis, berylliosis, asbestosis, Crohn disease, connective tissue disorders
      • Normal CD4/CD8: Tuberculosis, malignancies
      • Low CD4/CD8: acute hypersensitivity pneumonitis, silicosis, drug-induced lung disease, HIV infection, BOOP (COP)

Progressively darkening aliquots of bloody BAL fluid is highly suggestive of DAH. Hemosiderin-laden macrophages can also be evident on BAL analysis.

If chronic berylliosis is suspected, a positive lymphocyte proliferation test will be positive.

Treatment / Management

BAL is an excellent method of obtaining specimens to rule out opportunistic infections in immunocompromised individuals. It is important to combine culture results with cytology which may show viral intranuclear or intracytoplasmic inclusion bodies on examination of pulmonary epithelial cells. this may help identify viruses like herpes simplex and CMV. BAL is also very useful for detection of fungi and mycobacteria which may not always be identified in blood. The one big disadvantage of BAL is that many potentially pathogenic microorganism may have colonized the airways in the absence of any clinical disease and hence their recovery may not be meaningful.[7][8]

The use of BAL has been extensively studies in patients with interstitial lung disorders like hypersensitivity pneumonitis, sarcoidosis and idiopathic pulmonary fibrosis. Unfortunately, the findings of BAL are frequently not specific for these lung disorders and thus, the physician must also incorporate the clinical and imaging findings before making the diagnosis. In some disorders like acute eosinophilic pneumonia, BAL has saved the patient an unnecessary lung biopsy

BAL is also proving to be useful in evaluating individuals with occupational exposures to asbestos and other silicates. These macrophage-ingested occupational dust particles is usually visible in the fluid under polarized light.  BAL cytology is also useful for evaluating patients with malignancies of the airways.

 For the most part, BAL is performed for diagnostic purposes. However, BAL is uniquely used for the treatment of pulmonary alveolar proteinosis. This involves instilling 30 to 50 liters of sterile saline through a double lumen endotracheal tube while the patient is under general anesthesia.

Complications

The most common risks of the procedure are similar to those seen in flexible bronchoscopy. They include transient hypoxemia, post-BAL fever (seen in up to 30% of patients), bronchospasm, and very rarely pneumothorax. Given the low incidence, routine chest x-ray after the procedure is not performed unless clinically indicated.

Enhancing Healthcare Team Outcomes

Both the primary caregiver and nurse practitioner should be familiar with BAL. The technique involves instillation of sterile normal saline into a subsegment of the lung, followed by suction and collection of the instillation for analysis. This procedure is typically facilitated by the introduction of a flexible bronchoscope into a sub-segment of the lung. The procedure as we know it today was popularized in 1974 by the work of American physicians, Reynolds and Newball, in Maryland. Today, it serves predominantly as a diagnostic tool for the evaluation of lower respiratory tract pathology and in some uncommon conditions, also has therapeutic utility. While any health professional can perform BAL, the procedure is best performed by a pulmonologist or thoracic surgeon for optimal results.  


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Bronchoalveolar Lavage - Questions

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You are performing bronchoalveolar lavage in a patient in the intensive care unit who has had a fever for the past two weeks. All the other workup has been negative. You introduce the bronchoscope and instill 60 ml of normal saline into the right lower lobe. Upon suctioning, you only have a return of 5 ml. You repeat the process with another 60 ml of saline and again only get back 5 ml. What is the next step?



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A patient has been in the intensive care unit for over a month. He has had multiple problems and now has a fever and a diffuse infiltrative process in both lungs. Sputum, urine, and blood cultures are all negative and it is decided to perform a bronchoalveolar lavage. From which lobe of the lung will you try and perform the lavage in such a case?



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A 70-year-old farmer presents to the emergency department with a nonproductive exertional cough and easy fatiguability for the past 6 months. He also reports experiencing low-grade fever, weight loss, occasional shortness of breath, joint pain, and flu-like symptoms. He is a non-smoker and drinks alcohol socially. He has a history of diabetes mellitus for which he takes metformin daily. Auscultation of the chest reveals a vesicular murmur and bilateral crackles. A CT scan shows ill-defined centrilobular nodules most prominent in the upper lobes of both lungs. Bronchoalveolar lavage is planned. Which of the following bronchoalveolar lavage findings will be indicative of the condition causing this patient's symptoms?



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A 32-year-old female with a history of HIV infection is admitted with intermittent fever, dyspnea, and cough. She undergoes a bronchoalveolar lavage during which she receives 10 mL of 2% lidocaine solution instilled into the trachea as well as 2 sprays of 2% lidocaine solution. Benzodiazepines are given for moderate sedation. Shortly after the procedure the patient develops respiratory distress and was visibly cyanotic. Her vitals immediately after the procedure are the following: blood pressure is 180/72 mmHg, the pulse is 140/min, and oxygen saturation is 90% with satisfactory waveform. Which of the following diagnostic tests would be most helpful in identifying the underlying problem?



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Bronchoalveolar Lavage - References

References

Gibelin A,Parrot A,Fartoukh M,de Prost N, Rare respiratory diseases in the ICU: when to suspect them and specific approaches. Current opinion in critical care. 2019 Feb;     [PubMed]
Lachant DJ,Croft DP,McGrane Minton H,Hardy DJ,Prasad P,Kottmann RM, The clinical impact of pneumocystis and viral PCR testing on bronchoalveolar lavage in immunosuppressed patients. Respiratory medicine. 2018 Dec;     [PubMed]
Jain K,Wainwright C,Smyth AR, Bronchoscopy-guided antimicrobial therapy for cystic fibrosis. The Cochrane database of systematic reviews. 2018 Sep 17;     [PubMed]
Gharsalli H,Mlika M,Sahnoun I,Maalej S,Douik El Gharbi L,Mezni FE, The utility of bronchoalveolar lavage in the evaluation of interstitial lung diseases: A clinicopathological perspective. Seminars in diagnostic pathology. 2018 Sep;     [PubMed]
Lehrnbecher T,Hassler A,Groll AH,Bochennek K, Diagnostic Approaches for Invasive Aspergillosis-Specific Considerations in the Pediatric Population. Frontiers in microbiology. 2018;     [PubMed]
Pennington K,Wilson J,Limper AH,Escalante P, Positive {i}Pneumocystis jirovecii{/i} Sputum PCR Results with Negative Bronchoscopic PCR Results in Suspected Pneumocystis Pneumonia. Canadian respiratory journal. 2018;     [PubMed]
Salzer HJF,Schäfer G,Hoenigl M,Günther G,Hoffmann C,Kalsdorf B,Alanio A,Lange C, Clinical, Diagnostic, and Treatment Disparities between HIV-Infected and Non-HIV-Infected Immunocompromised Patients with Pneumocystis jirovecii Pneumonia. Respiration; international review of thoracic diseases. 2018;     [PubMed]
Sizar O,Talati R, Berylliosis (Chronic Beryllium Disease) 2018 Jan;     [PubMed]

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