Pulmonary Function Tests
Pulmonary function tests measure how well air moves in and out of your lungs and how well oxygen enters your bloodstream. The most commonly ordered pulmonary function tests are spirometry, lung volumes, and diffusion capacity. These tests simply involve breathing through a mouthpiece into a tube connected to a machine (spirometer). The tests do not hurt and there are no needles or x-rays involved.
Spirometry helps to determine if the bronchial tubes are constricted, such as in conditions like asthma or emphysema. The spirometer measures how much air you can breathe into your lungs and how much air you can quickly blow out of your lungs. The test is often repeated after a certain medication (bronchodilator) is administered to find out how much better you might breathe with this type of medicine.
Lung volumes measure the size of the lungs. Lung volume can be diminished in conditions such as pulmonary fibrosis. Measuring the total amount of air your lungs can hold and the amount of air left in your lungs after you breathe out gives us information about how well your lungs are working.
Diffusion tests measures how well oxygen transfers from your lungs into your bloodstream.
Methacholine Challenge Test
Challenge studies are types of tests that measure whether your lung function changes after you inhale specific chemicals. In the United States, the most common chemical used is methacholine.
The challenge study is designed to see if your airways tighten after you have inhaled a small dosage of methacholine. If your airways do tighten during the test, you may have symptoms of an “asthma attack.” You may cough, wheeze, feel chest tightness or be short of breath. If the test results show that your airways are tightening, you will be given a bronchodilator to relieve your symptoms and re-open your airways. Often, the person administering the test will know that your airways are tightening before you do because of the spiromery test you will be asked to perform before and following each step of the test.
Bronchoscopy is a procedure that enables physicians to examine the upper and lower airway passages. The procedure is indicated when it is necessary to see inside the airways of your lungs, or obtain samples of mucus or tissue from the lungs. Bronchoscopy involves placing a thin tube-like instrument called a bronchoscope through the nose or mouth and down into the airways of the lungs. The tube has a mini-camera at its tip, and is able to carry pictures back to a video screen or camera.
A lung biopsy is often performed to evaluate any abnormalities seen on other tests such as a chest x-ray or CT scan. Through this procedure, cells from a suspicious area within the lung tissue can be removed and examined under a microscope to determine the diagnosis.
Thoracentesis is a procedure that is done to remove a sample of fluid from around the lung. The lung is covered with a tissue called the pleura. The inside of the chest is also lined with pleura. The space between these two areas is called the pleural space. This space normally contains just a thin layer of fluid, however, some conditions such as pneumonia, cancer, or congestive heart failure may cause excessive fluid to develop.
Thoracentesis involves placing a thin needle or tube into the pleural space to remove some of the fluid. The needle or tube is inserted through the skin, between the ribs and into the chest. This procedure may be done to remove fluid for diagnostic testing or for treatment.