Georgetown University - Department of Medicine

The Medstar Georgetown University Hopital Pulmonary Function Testing Laboratory offers comprehensive pulmonary function testing, cardiopulmonary exercise testing, and arterial blood gas assessment in a state-of-the-art laboratory.

What are pulmonary function tests?

Pulmonary function tests (PFTs) measure how well your lungs take in and exhale air and how efficiently they transfer oxygen into the blood. There are several different kinds of tests your healthcare provider may order:
Spirometry measures how well the lungs exhale (breathe out).
Lung volumes measure how well the lungs breathe in (inhale) and how much air they contain.
Diffusing Capacity for Carbon Monoxide (DLCO) shows how efficiently the lungs transfer oxygen from the air into the bloodstream.
Arterial Blood Gas analysis measures the amounts of oxygen and carbon dioxide and the pH of an arterial blood sample. Most often the blood sample is obtained in the laboratory via the radial artery (near the wrist).

Why are these pulmonary function tests done?

To determine the cause of shortness of breath
To aid in diagnosis of lung diseases, such as asthma, chronic bronchitis, and emphysema
To measure how much exposure to chemicals, coal dust, and other toxins affects your lung function
To measure the effectiveness of medications and other treatments for lung disease
PFTs may also help detect lung disease at an early stage before symptoms develop

Additional Specialized Pulmonary Function Tests:

Methacholine Challenge may be helpful in evaluating unexplained cough or possible asthma. A patient performs repeated spirometry tests following inhalation of the chemical methacholine. In some patients with hyperreactive airways, methacholine may cause a transient change in airways function which is detected by spirometry testing.
Cardiopulmonary Exercise Testing refers to any one of a family of tests in which measurements are made while a patient performs exercise.
- Desaturation Test- measurements of heart rate and oxygen saturation from pulse oximetry (finger probe) are recorded while the patient walks on a treadmill or in a hallway. This test is used primarily to detect and quantify the need for supplemental oxygen.
- Six Minute Walk Test- measures the maximal distance that a patient can walk in six minutes at his/ her own pace in a hallway. This test is used to measure exercise performance and assess response to treatments.
- Cardiopulmonary Exercise Testing with Gas Analysis- a more sophisticated form of exercise testing in which measurements of breathing, as well as heart rate and oxygen saturation are recorded while the patient pedals a stationary bicycle or walks on a treadmill. The test progresses with increasing resistance on the bicycle/treadmill until the patient fatigues. Heart function is monitored by electrocardiograph and blood pressure. The collection of exhaled gases permits calculation of the patient’s response to external work. The most important result is the maximal oxygen consumption (VO2 max), the amount of oxygen fuel consumed each minute. This test may be helpful in evaluating causes of shortness of breath or decreased exercise tolerance. It may also be helpful in distinguishing between cardiac and pulmonary limitations.