Pulmonary Function Laboratory: Minute Volume Ventilation Body Box -The body box test (also known as plethysmography) is done sitting in an enclosed clear chamber. You will be asked to perform a series of very small panting breaths. If you are claustrophobic, you may be uncomfortable doing this test. Let the technologist know if you are having problems. Lung Volumes - Lung volumes measure different parts of the breath to determine how much air you can breathe in and out. Some of the volumes are: total lung capacity (maximum amount of air in you lungs after a deep inspiration), vital capacity (maximum amount of air that can be exhaled normally after a maximum inhalation), functional residual capacity (amount of air in your lungs at the end of a normal exhalation), and residual volume (amount of air remaining in the lungs after a maximum exhalation). Diffusing Capacity - The diffusing capacity of the lungs (DLCO) measures how well gases such as oxygen move from the lungs into the blood. The most common way to measure the DLCO is the ten-second single-breath-hold technique. If you cannot hold your breath for 10 seconds, it will be difficult for you to perform the test.