Pulmonology is a sub-specialty of Internal Medicine. Pulmonologists specialize in diseases of the lungs and respiratory tract. Common signs or symptoms of respiratory disease which might prompt evaluation by a lung doctor include an abnormal CXR or CT scan, chronic cough, shortness of breath, chest pain, or recurrent lung infections.
Pulmonologists diagnose and treat many different types of lung diseases:
- Acute and chronic pulmonary infections
- Chronic bronchitis
- Lung cancer
- Pulmonary embolism
- Pleural effusions
- Pulmonary hypertension
- Pulmonary Fibrosis
- Occupational lung diseases such as asbestosis or silicosis
Pulmonologists use many different diagnostic tools to evaluate the structure and function of the lungs. Commonly, patients are asked to have a chest x-ray and basic breathing tests, called spirometry, on the initial visit. A description of these and other common diagnostic tests is briefly mentioned below.
Chest x-rays provide the treating physician with a 2-dimensional image of the structure of the lungs. Many common diseases can be visualized, or ruled out, by examination of these images. Examples of diseases in which chest x-rays are helpful include pneumonia, congestive heart failure, fluid collections outside the lungs but in the chest cavity, tumors, and diseases of the lining of the lung.
Your physician will review your chest x-ray results with you in detail.
A CT scan is a more advanced imaging study as compared to an x-ray. Whereas a chest x-ray provides a flat, 2-dimensional image of the chest, the CT scan uses computers to render a 3-dimensional image of the chest and its internal structures, including the lungs, major blood vessels, lymph nodes, and other important structures in the chest. The CT scan creates images that are thin slices of the chest, analogous to slicing a loaf of bread.
A CT scan may be ordered to evaluate a variety of different pulmonary diseases. Some, but not all, CT scans require the use of intravenous contrast to delineate specific structures in the chest. You should tell your doctor if you take the diabetes medicine Glucophage (Metformin), if you have kidney disease, or if you have an allergy to iodine before undergoing a contrasted CT evaluation.
VENTILATION – PERFUSION SCAN
The Ventilation-Perfusion scan is a test performed in the hospital as an outpatient by Nuclear Medicine. This test compares the distribution of air in the lungs to the distribution of blood flow to the lungs. It is commonly ordered to evaluate for the possibility of pulmonary embolism, or blood clot that has migrated to the lung and occluded one of the blood vessels in the lung. In this case, the study would indicate normal air flow, but impaired blood flow, to a region of lung tissue.
PULMONARY FUNCTION TESTING
Pulmonary Function Testing is another basic test in pulmonary medicine. Pulmonologists use these tests to broadly classify lung diseases into one of a few basic categories, such as obstructive lung diseases (COPD, bronchiectasis, etc.) or restrictive lung disease (obesity, pulmonary fibrosis, etc.).
Full pulmonary function testing also quantitatively assesses the lungs ability to absorb oxygen properly by assessing a property called the diffusion capacity. The diffusion capacity, or ability of the lung to move oxygen from the air to the blood, can be impaired by many diseases, such as smoking related lung injury.
A bronchodilator assessment looks for the presence of airway hyper-reactivity, a feature of asthma. This test involves performing some breathing maneuvers, taking an inhaler, and then repeating the breathing maneuvers.
METHACHOLINE CHALLENGE TESTING
Methacholine challenge testing is the gold standard for the diagnosis of asthma. In this test, the patient inhales a medication and then performs a breathing maneuver. This procedure is repeated 6 times with increasing doses of medication. A patient without asthma will not have a significant change in lung function. A patient with asthma will have a measurable difference in lung function.
ARTERIAL BLOOD GAS
Arterial blood gas analysis give the Pulmonologist a lot of information about how well the lungs absorb oxygen and expel the waste gas carbon dioxide. In the outpatient setting this test is helpful in pre-operative risk assessments in patients with chronic lung diseases.
6 MINUTE WALK TIME
The six minute walk test is a standardized test in pulmonary medicine that affords the physician insight into how a lung disease might be impacting you functionally. As the name suggests, the test involves the patient walking for six minutes; the distance walked is recorded, “along with various PATIENT vital signs. Following the six minute walk time longitudinally offer prognostic information about the progression of lung diseases.
This non-invasive test typically involves placing a finger probe on the patient to check the blood oxygen level. Then, the patient is walked briefly to assess whether the oxygen level falls with exercise. This test is useful to help determine which patients need supplemental oxygen administration.
CARDIOPULMONARY EXERCISE TESTING
Cardiopulmonary exercise testing is often used by pulmonologists and cardiologists (heart doctors) to help determine the cause of shortness of breath. Shortness of breath can be secondary to many factors, including chronic lung disease or chronic heart disease. For this test, the patient is exercised, typically on a bicycle, and various heart and lung parameters are monitored continuously. Interpretation of the test can help physicians learn whether a patient’s shortness of breath is more likely to be caused by cardiac or pulmonary limitations.
Bronchoscopy is a procedure performed in the hospital as an outpatient. The patient is sedated with IV medications, and a camera on a thin scope is introduced into the lungs, typically via the nose. Because the patient is sedated, it is not a typically uncomfortable procedure. Bronchoscopy can be used to inspect the air pipes for abnormalities. Bronchoscopy can also be used to sample lung tissue in the evaluation of various diseases. Two common types of samples include bronchoalveolar lavage and transbronchial biopsy.
Bronchoalveolar lavage consists of washing an area of lung with water from the inside; the water mixes with cells in the region of diseased; then the water is sucked back through the scope where it is collected and sent to the laboratory for analysis. This procedure is helpful in diagnosing many different types of lung diseases, including infections, inflammatory disorders, and some cancers.
Endobronchial Ultrasound-guided Biopsy (or EBUS). EBUS is a technique used to biopsy masses, enlarged lymph nodes, or tumors that abut the major air pipes in the lungs. Like bronchoscopy (described above) this procedure is performed on a sedated patient. With EBUS, the bronchoscope has an ultrasound probe and biopsy needle on the end. The ultrasound probe uses sound waves to create a visual map of structures abutting the air pipes, allowing the pulmonologist to exactly identify the location of the abnormality in question. After identification, the biopsy needle can be used to obtain cells from the tissue in question.
Thoracentesis is a common procedure, performed as an outpatient in a procedure room or at the bedside in an inpatient, to drain fluid out of the pleural space. This procedure is performed with local anesthesia, also known as a numbing shot. The pleural space is a potential space between the chest wall and the lungs; fluid can accumulate in this space in a variety of diseases, including heart failure, after a trauma, or with infection. This procedure is often performed under ultrasound guidance, allowing the pulmonologist to visualize the pocket of fluid before sampling it and enhancing safety.