What are they and why do I need them?

Chest x-rays and CT scans show if there are any abnormalities affecting the lungs. Pulmonary Function Tests indicate how the lungs are functioning; specifically, are the lungs able to bring enough oxygen into the air sacs and allow the oxygen to get into the blood for use by other vital organs? In order to measure how the lungs are working, the clinician may order Pulmonary Function Tests. These tests are usually performed in order to follow for the progression of lung disease and are also used preoperatively to determine if surgery is feasible. Pulmonary Function Tests consist of a battery of measurements, done in facilities called Pulmonary Function Laboratories, and are designed to measure the volumes and flow of air that enter and leave the lungs, as well as how efficiently the gases are able to pass from the air sacs into the blood.

Some of the most common Pulmonary Function Tests are:

1. Spirometry involves asking the patient to breathe in deeply and exhale as fully and forcibly as possible, so that the measurement of the lungs’ ventilatory function can be assessed.

2. Body plethysmography is a test that measures the gas volume of the lung, using changes of pressure that occur during breathing.

3. Diffusion capacity entails asking the patient to breathe in small amounts of carbon monoxide and measure how much of this gas gets into the blood; (this indicates the ability of the lung to allow oxygen into the blood).

4. Arterial blood gas measurements are performed by extracting a minute amount of blood from one of the small arteries in the body (usually in the wrist) in order to analyze the amount of oxygen and carbon dioxide in the blood.