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Tell me about Allergies!



1. What is spirometry?

2. When should Spirometry testing be done?

3. What does Spirometry measure?

4. How is Spirometry done?

5. What information does it give my doctor?




What is Spirometry?


Spirometry is also known as Pulmonary Function Testing. It is a painless, noninvasive test that evaluates and measures how easily air moves in and out of your lungs. It takes about 10 minutes to perform, and provides immediate results that can help to detect lung disease. 

Exposure to certain irritants or allergens such as animals, smoke, weeds, grasses, trees or chemicals can cause the muscles surrounding the airway to spasm and cause narrowing of the bronchi or airways. This narrowing makes it hard to breathe air in and out. 





When should Spirometry testing be done?


Spirometry should be done on patients who have symptoms of:

  • shortness of breath
  • chest tightness
  • wheezing
  • chest pain
  • Who are > 45years old, currently smoke or have quit in the last year.
  • To assess therapeutic interventions (e.g., bronchodilator therapy, steroid treatment, management of CHF, etc.)
  • To assess preoperative risk.
  • To screen individuals at risk of having pulmonary diseases (e.g., smokers, occupational exposure)
  • To assess health status before enrollment in strenuous physical activity programs.
  • To assess patients as part of a rehabilitation program.
  • To assess risks as part of an insurance evaluation.



What does Spirometry measure?

Spirometry measures:

FEV1 - forced expiratory volume in 1 second (the amount of air that can be forcibly exhaled during the first second of the test. Normal is about 80-100% of predicted.

FVC – forced vital capacity, how much air the lungs are able to hold. Normal is about 80-100% of predicted. A decrease in the FVC may indicate lung disease.

FEV1 / FVC - forced expiratory volume in 1 second divided by the forced vital capacity. This yields a ratio.  Normal is above 75% and decreases with age. A decrease in this ratio indicated obstructive lung disease. Examples of obstructive lung disease are: reactive airway disease, asthma, bronchitis and emphysema. 

FEF 25-75% - Forced Expiratory Mid-Flow. This measures how fast the air was coming out of your lungs during the middle two parts of your breathe. Normal is greater than 80% of predicted.


How is Spirmoetry done?


You will be asked to hold a plastic disposable Spirometer sensor tube in your mouth. You may have a clip placed on your nose or asked to pinch your nose closed. You will be asked to inhale as deeply as you can holding the sensor steady, then instructed to blow into the tube as hard and as fast as you can for 6 seconds. 

The test may make you tired or short of breath. You can rest between repeated tests if you like. It is important to have a closed seal around the mouthpiece and no air going through the nose to get an accurate measurement.

As you exhale into the tube, a computerized sensor in the Spirometer calculates your FEV1 and your FVC, the FEV1/FVC ratio and other measures. Your results will be automatically compared to what is predicted for your age, gender, height and race. The doctor may order a nebulizer breathing treatment with a bronchodilator medication, such as albuterol, to relax the muscles surrounding the airways. After the medication has had time to work, spirometry is repeated. If there is a certain percentage of improvement in the test measurements, that means the obstruction is reversible. The doctor may prescribe a fast acting bronchodilator called a rescue inhaler. If there is no immediate improvement, it is possible that the obstruction will respond to slower acting drugs that reduce inflammation.