Bronchoalveolar lavage (BAL) (also known as bronchoalveolar washing) is a diagnostic method of the lower respiratory system in which a

bronchoscope Bronchoscopy is an endoscopic technique of visualizing the inside of the airways for diagnostic and therapeutic purposes. An instrument (bronchoscope) is inserted into the airways, usually through the nose or mouth, or occasionally through a trac ...

is passed through the mouth or nose into an appropriate airway in the

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

s, with a measured amount of fluid introduced and then collected for examination. This method is typically performed to

diagnose Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine "cause and effect". In systems engineer ...

pathogenic

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...

s of the lower respiratory airways (leading to, for example

pneumonia Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severit ...

and COVID-19), though it also has been shown to have utility in diagnosing

interstitial lung disease Interstitial lung disease (ILD), or diffuse parenchymal lung disease (DPLD), is a group of respiratory diseases affecting the interstitium (the tissue and space around the alveoli (air sacs)) of the lungs. It concerns alveolar epithelium, pulm ...

. Bronchoalveolar lavage can be a more sensitive method of detection than nasal swabs in respiratory molecular diagnostics, as has been the case with SARS-CoV-2 where bronchoalveolar lavage samples detect copies of viral RNA after negative nasal swab testing. In particular, bronchoalveolar lavage is commonly used to diagnose infections in people with immune system problems,

in people on

ventilators A ventilator is a piece of medical technology that provides mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to breathe, or breathing insufficiently. Ventilators ...

, and

acute respiratory distress syndrome Acute respiratory distress syndrome (ARDS) is a type of respiratory failure characterized by rapid onset of widespread inflammation in the lungs. Symptoms include shortness of breath (dyspnea), rapid breathing (tachypnea), and bluish skin colo ...

(ARDS). It is the most common method used to sample the epithelial lining fluid (ELF) and to determine the protein composition of the pulmonary airways. BAL has even been used therapeutically to remove mucus, improve airway ventilation, and reduce airway inflammation in conditions such as

chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce m ...

(COPD) and

pulmonary alveolar proteinosis Pulmonary alveolar proteinosis (PAP) is a rare lung disorder characterized by an abnormal accumulation of surfactant-derived lipoprotein compounds within the alveoli of the lung. The accumulated substances interfere with the normal gas exchange a ...

(PAP).

Equipment and procedure

The primary equipment used in BAL includes a fiber-optic bronchoscope, sterile collection traps for collecting test specimens, a sterile saline source, a suction device, and suction tubing. Essentially, the saline source is connected to sterile bronchoscope, as is the specimen collection trap, and then suction tubing is connected to the trap and the suction source. If the bronchoscope is not sterile, saline should initially be used to flush it clean. With the patient under some sort of anesthesia (depending on the rigidity of the scope), the fiber-optic cable is lowered into the correct area of the lower lungs (

tracheobronchial tree The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa. Air is breathed in through the nose to th ...

), wedged into place, and saline applied. Once the saline is fully applied, then either suction is applied to collect the fluids, or the fluids are collected with a sterile syringe through the irrigation channel. The collection trap is then appropriately labeled and sent off for testing.

References

{{DEFAULTSORT:Bronchoalveolar Lavage Diagnostic pulmonology Respiratory system procedures

Equipment and procedure

See also

References