SPIROMETRY

The first and most commonly done lung function test. It measures how much and how quickly you can move air out of your lungs. For this test, you breathe into a mouthpiece attached to a recording device (spirometer).

 

Why the Spirometry Test?

• Diagnose lung diseases:     Ex 1: Asthma, Bronchitis, COPD and Emphysema (diseases that affect how fast you can breathe air out)                                                                                                      Ex 2: Pulmonary Fibrosis and Asbestosis (diseases that affect how much air you can breathe in).
• Find the cause of shortness of breath
• Measure whether exposure to contaminants at work affects lung function

• Assess the effect of medication
• Measure progress in lung disease treatment

Common lung function values measured with spirometry are:

• Forced vital capacity (FVC). The amount of air you can exhale with force after you inhale as deeply as possible.
• Forced expiratory volume (FEV). The amount of air you can exhale with force in one breath. The amount of air you exhale may be measured at 1 second (FEV1), 2 seconds (FEV2), or 3 seconds (FEV3). FEV1 divided by FVC can also be determined.
• Forced expiratory flow 25% to 75%. The air flow halfway through an exhale.
• Peak expiratory flow (PEF). How quickly you can exhale. (usually measured at the same time as (FVC).
• Maximum voluntary ventilation (MVV). The greatest amount of air you can breathe in and out during one minute.
• Slow vital capacity (SVC). The amount of air you can slowly exhale after you inhale as deeply as possible.
• Total lung capacity (TLC). The amount of air in your lungs after you inhale as deeply as possible.
• Functional residual capacity (FRC). The amount of air in your lungs at the end of a normal exhaled breath.
• Residual volume (RV). The amount of air in your lungs after you have exhaled completely. Done by breathing in helium or nitrogen gas and seeing how much is exhaled.
• Expiratory reserve volume (ERV). The difference between the amount of air in your lungs after a normal exhale (FRC) and the amount after you exhale with force (RV).

Normal values are based upon age, height, ethnicity, and sex. Normal results are expressed as a percentage and is considered abnormal if less than 80% of your predicted value.

VO2 MAX /AEROBIC CAPACITY

VO2 max is defined as "the highest rate of oxygen consumption attainable during maximal or exhaustive exercise." As exercise intensity increases so does oxygen consumption. However, a point is reached where exercise intensity can continue to increase without the associated rise in oxygen consumption.

The point at which oxygen consumption plateaus defines the VO2 max or an individual's maximal aerobic capacity. It is generally considered the best indicator of cardiorespiratory endurance and aerobic fitness.

Factors affecting VO2 Max

Aside from genetic factors, three other components have a large influence on VO2 max:

• Age - Although it varies greatly by individual and training programs, in general VO2 max is the highest at age 20 and decreases nearly 30 percent by age 65.
• Gender - Many elite female athletes have higher VO2 max values than most men. But because of differences in body size and composition, blood volume and hemoglobin content, a woman's VO2 max is in general about 20 percent lower than a man's VO2 max.
• Altitude - Because there is less oxygen at higher altitude an athlete will generally have 5 percent decrease in VO2 max results with a 5,000 feet gain in altitude.