Pulmonary Function Testing

Cough, shortness of breath, and wheezing are very common symptoms. There are several tests that can help determine the exact cause of these symptoms. Coupled with a detailed medical history and a physical examination, these tests help us determine the root cause of your symptoms and guide the selection of the most effective treatments.

Lung function tests, also called pulmonary function tests or PFTs, check how well your lungs are functioning. These tests determine how much air your lungs can hold and how quickly you can move air in and out of your lungs. It can detect airway obstruction, a common feature of asthma, and whether such obstruction resolves after inhaling asthma medications, called bronchodilators (such as albuterol).

In cases where spirometry test results are inconclusive, a methacholine or mannitol challenge test may also be recommended by your asthma specialist. During a methacholine or mannitol challenge, you inhale increasing amounts of either methacholine or mannitol. After each dose, breathing tests will be performed to measure any resulting changes in your lung function. People with asthma are more sensitive to the agents and a positive test confirms the diagnosis of asthma.

In some cases, more detailed pulmonary function tests are needed. Such tests, commonly called ‘complete PFTs’ require specialized equipment and may require a referral to a local resource.

While allergic airway inflammation is known to be the major underlying cause of asthma, there are few methods of measuring it. Patients with allergic airway inflammation generally have higher than normal levels of nitric oxide (NO) in their exhaled breath. By measuring the concentration of NO in an exhaled breath (fractional exhaled nitric oxide or FeNO), we can evaluate allergic airway inflammation in patients with underlying asthma.

While various breathing tests are important ways in determining the cause of cough, wheeze, and shortness of breath they are also very valuable tools to track your condition over time and ensure that the treatments you are using are delivering the results you expect.