Alveolar lavage, also known as bronchoalveolar lavage (BAL), is a medical procedure that gathers fluid samples from the lungs. It involves washing a specific area within the lung’s air sacs to collect cells and other substances. This technique serves as a diagnostic tool for investigating various lung conditions.
Understanding Alveolar Lavage
Alveolar lavage introduces a small amount of sterile fluid, typically saline, into a specific segment of the lung’s tiny air sacs, called alveoli. The fluid is then immediately suctioned back. This collected fluid contains cells and other components from the lung’s lower respiratory tract. Examining these components provides valuable information about lung health and helps identify underlying conditions.
Diagnostic Applications
Alveolar lavage is widely used to diagnose a range of lung conditions, particularly infections and inflammatory lung diseases. It helps identify pathogenic infections in the lower respiratory airways, such as bacterial, viral, fungal, and parasitic infections like Pneumocystis jirovecii pneumonia, especially in immunocompromised individuals. The procedure also aids in diagnosing inflammatory lung diseases, including sarcoidosis, hypersensitivity pneumonitis, and eosinophilic pneumonia. It can detect certain types of lung cancers and diffuse alveolar hemorrhage, a condition where small blood vessels in the lungs bleed. In some cases, alveolar lavage provides a more sensitive method for detecting pathogens, such as SARS-CoV-2, compared to nasal swabs.
The Procedure Explained
Alveolar lavage is performed during a bronchoscopy, which uses a thin, flexible tube called a bronchoscope. Before the procedure, patients are asked to fast. Local anesthesia is applied to the mouth and throat to minimize discomfort, and a sedative is administered for relaxation or sleep.
During the procedure, the bronchoscope is inserted through the mouth or nose and guided into the airways. A camera on the bronchoscope allows the healthcare provider to visualize the airways and lungs on a video screen. Once positioned in a lung subsegment, sterile saline is instilled through the scope, and after a brief dwell time, the fluid is suctioned back into collection traps. This process may be repeated several times. The entire bronchoscopy with lavage takes about 30 to 90 minutes, during which patients are monitored for oxygen saturation, heart rate, and blood pressure to ensure their safety and comfort.
What Lavage Fluid Reveals
The collected lavage fluid contains cellular and non-cellular components from the lung’s lower respiratory tract. Laboratory analysis of this fluid involves examining different types of cells, such as macrophages, lymphocytes, neutrophils, and eosinophils, and determining their proportions.
Beyond cells, the fluid is also analyzed for proteins, which can indicate inflammatory responses, and for the presence of microorganisms like bacteria, fungi, and viruses. Microscopic examination and cultures identify specific pathogens. The presence of certain substances or specific cell patterns can provide clear indications of particular lung diseases.
Risks and Recovery
While considered safe, alveolar lavage carries risks and side effects. Common, usually temporary, side effects include a cough, sore throat, or mild shortness of breath. Patients may also experience a transient fever.
Less common but more serious complications include bleeding in the airways, infection, or pneumothorax, which is a collapsed lung. Hypoxemia, or low oxygen levels, can also occur during or after the procedure. After the procedure, patients are monitored in a recovery area until the effects of sedation wear off. Post-procedure care includes resting and avoiding strenuous activities. Patients are advised to seek medical attention if they experience persistent or worsening symptoms like significant difficulty breathing, chest pain, or fever.