Spirometry

The need for spirometry or lung testing

Spirometry is a common method for measuring and recording the respiratory capacity of the lungs. Spirometry is used to measure some lung volumes and capacities in lung patients such as asthma, chronic obstructive pulmonary disease (COPD), and restrictive lung diseases to diagnose and assess the severity of the disease. Spirometry is also performed periodically to assess the lung function of people with chronic diseases and workers exposed to lung diseases. Spirometry is a method used paraclinically to detect lung failure. Today, spirometry is the most important, most accessible, and least expensive test to assess lung function. To take spirometry, you breathe into a small device called a spirometer. This medical device records the amount of air you send in and out of your lungs and the rate of breathing.

How is spirometry performed?

During a spirometry test, which usually takes about 15 minutes, you sit in a chair. The doctor places a clip over your nose to close your nostrils and allow all the air you are about to inhale to come in through your mouth. A breathing mask is then placed over your mouth. The doctor tells you to take a deep breath and hold it for a few seconds. Then, breathe out as hard as you can. You will need to do this test at least three times to be sure of the results. If there is a big difference between the results, you may be asked to repeat the test a few more times. The highest of the three close results is recorded as the final result. If there is evidence of a lung problem, you may be given an inhaled medication, such as a bronchodilator. You will then wait 15 minutes and repeat the tests. The doctor will compare the results of the two sets of tests before and after the medication to see if the inhaler helped increase airflow in the lungs.

Spirometry measures two key factors:

Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) The doctor measures the ratio of the volume you exhale, or forcefully exhaled, in one second to your forced vital capacity. If your airways are blocked, the amount of air you can quickly exhale from your lungs is reduced. This means your forced expiratory volume is lower than your forced vital capacity.

What is the normal spirometry value?
The normal result of a spirometry test varies from person to person. The normal value for each person is determined based on age, height, race, and gender. Your doctor will determine your normal value based on this and then perform the test. He or she will then compare your score with the expected normal value. If the test result is 80 percent or higher than the predicted value, it means that the condition is normal. The Centers for Disease Control and Prevention has a program on its website to easily calculate the normal value of a spirometry test for each person, which you can use to find out what is normal for you.

What are the complications of spirometry?
There are no specific side effects during or after the spirometry test. You may feel a little dizzy or short of breath immediately after the test. In very rare cases, the test may trigger severe breathing problems. Performing spirometry puts a little strain on the body, so if you have recently had a heart problem or have a heart condition, this test may not be suitable for you, so be sure to tell your doctor beforehand.

Preparation conditions for performing a spirometry test

  • A person should not eat much food for three hours before performing spirometry.
  • People being tested must be alert and able to cooperate.
  • The person should wear comfortable clothing. If tight clothing restricts chest movement, it is necessary to remove tight clothing.
  • Adults should be seated or standing comfortably.
  • Do not use inhaled medications for a few hours before the test.
  • The patient is not prohibited from performing a spirometry test by a doctor (in cases such as chest surgery, eye or ear surgery, heart attack or unstable angina, evidence of respiratory distress, recent stroke, high blood pressure, etc.)
  • Height and weight should be measured, questions about age, race, and smoking status should be asked, and the information should be recorded in the device.
  • Diseases such as tuberculosis can contaminate the spirometry device, and these people should inform their doctor before using the device.

What is a spirometry test used for?

  • Early and timely diagnosis of pulmonary diseases (asthma, COPD, bronchitis, etc.) and determination of the severity of airway obstruction
  • Timely treatment and prevention of complications of lung diseases and respiratory disabilities
  • Helping to differentiate between cardiac and pulmonary shortness of breath
  • Follow-up of pulmonary diseases to continue or change the type or amount of drug treatments (sprays)
  • Pre-employment examinations to determine the individual’s suitability for the desired job and occupation
  • Periodic annual occupational medicine examinations to check for occupational diseases and maintain the health of workers
  • If necessary, recommend job changes or restrict sick workers.
  • Determining the risk of certain surgeries using pulmonary function testing (spirometry)

What are the contraindications to using spirometry?

  • Bloody sputum of unknown origin
  • Untreated air in the pleural space (pneumothorax)
  • Unstable cardiovascular condition
  • Aneurysms and dilation of abdominal or cerebral vessels
  • Relative prohibition on recent cataract surgery
  • The presence of an acute illness that causes the patient to not cooperate (nausea – vomiting)
  • Recent abdominal and thoracic surgeries