Spirometry is a crucial diagnostic tool in respiratory medicine, offering valuable insights into lung function. This article will explore the ins and outs of spirometry, from its purpose to the preparation and interpretation of results.
What is a spirometry test?
Spirometry, also known as a lung function test, is a common type of pulmonary function test that measures how well your lungs work. It quantifies the volume of air you can inhale and exhale, as well as the speed at which you do so. It does this by measuring the flow of air through your lungs and estimating the amount of air in your lungs.
Healthcare professionals use spirometry to diagnose and monitor various respiratory conditions, including asthma, chronic obstructive pulmonary disease (COPD), and other lung disorders that affect your ability to breathe. If you have a lifelong lung condition, your healthcare providers may also use a spirometer to check the condition of your lungs and see whether you need treatment to help you breathe better.
Why may you need a spirometry?
Spirometry can determine if your lungs are functioning at their expected levels and is recommended for several reasons:
Diagnosis
Your doctor may recommend a spirometry test if they feel that you have an increased risk of developing a lung condition.
If you're experiencing symptoms like persistent cough or breathlessness, or if you're over 35 and smoke, your doctor may recommend spirometry to diagnose conditions such as asthma or COPD.
Monitoring
For those with existing lung conditions, spirometry helps track the progression of the disease and evaluate the effectiveness of treatments by measuring the changes that occur over time due to pre-existing or chronic lung diseases.
Pre-operative assessment
Your doctor may order spirometry before planned surgery to assess your lung function and estimate your risk of respiratory complications before you undergo it.
Occupational screening
Some jobs require routine spirometry tests to check for lung disorders related to workplace exposures.
Thus, spirometry can help pick up and monitor many different types of conditions, such as a narrowed airway and lung conditions such as COPD or genetic conditions where the lungs become clogged with mucus.
How is a pulmonary function test (spirometry) procedure done?
You'll be seated and asked to wear a nose clip to ensure that no air is escaping from your nose and you are breathing only through your mouth.
You'll take a deep breath and then exhale as hard, fast, and long as you can into a mouthpiece with a tube connected to the spirometer. Ensure that you inhale and exhale fully during this part of the procedure.
This process is usually repeated three times to ensure that consistent and reliable results are obtained.
In some cases, you may be given medication and then be retested after 15 minutes to assess your response to treatment. This helps determine whether you have any lung conditions that improve with the medication.
The entire process typically takes around 30 to 90 minutes, and you can go home and return to your normal day-to-day activities after the testing has finished.
Have further questions about the spirometry test? Get in touch with our healthcare specialists here.
Preparing for the test
Your doctor will usually provide you with all the necessary information to prepare for the test. However, to ensure accurate results, you can follow these preparation guidelines:
Wear loose-fitting clothing that won't restrict chest and abdominal expansion.
Avoid large meals for at least 2 hours before the test.
Refrain from smoking for at least 24 hours before the test.
Skip heavy exercise for at least 30 minutes prior to testing.
Avoid alcohol for at least 8 hours before the test.
Follow your doctor's instructions regarding medication use, especially bronchodilator medicine (medicines that are usually inhaled and help relax and widen your airways), as you may need to stop using them beforehand.
Risks of a spirometry test
Spirometry is generally a safe and straightforward procedure with minimal risks.
However, you may experience:
Shortness of breath or dizziness immediately after the test, which usually subsides quickly.
Coughing.
Increased pressure inside your head, chest, stomach, and eyes during the test.
Spirometry may not be safe for those who have had previous heart attacks, uncontrolled high blood pressure, unstable angina or previous operations on their head, chest, stomach or eyes, as it leads to increased pressure in these areas. The test may be delayed if your doctor deems that your condition may worsen due to the increased pressure.
How to interpret spirometry test results?
Usually, you will not be able to get your results immediately, as they will need to be analysed by a specialist first. Spirometry results are typically expressed in terms of the terminology below:
1) Forced vital capacity (FVC)
The total amount of air you can forcefully exhale. If your FVC is lower than expected, something is restricting your breathing. You may have either restrictive lung disease, obstructive lung disease, or a combination of both.
2) Forced expiratory volume in one second (FEV1)
The amount of air you can exhale in the first second. This measurement helps your doctor evaluate how severe your breathing issues are.
3) FEV1/FVC ratio
The percentage of your total lung capacity that you can exhale in one second. The higher your FEV1/FVC ratio is, the healthier your lungs are.
Your doctor will interpret these values based on your age, height, sex, and race to determine if your lung function is normal or indicates a potential respiratory condition. The measurements will show if you have 'obstructive' or 'restrictive' problems with your lungs or if you have a combination of the two.
Obstructive lung disease
Obstructive lung disease is when your ability to breathe out is affected by the narrowing of the airways, but the amount of air you can hold in your lungs is normal. This condition happens when the airways are narrowed or blocked, making it difficult to exhale air fully from the lungs. This leads to trapped air, causing shortness of breath and wheezing — common in conditions like chronic obstructive pulmonary disease (COPD), asthma, and bronchiectasis.
Spirometry plays a key role in diagnosing obstructive lung disease by measuring how much air you can forcefully exhale in one second (FEV1) and the total amount of air exhaled (FVC). A lower-than-normal FEV1/FVC ratio usually indicates an obstruction, helping doctors assess the severity and guide treatment.
Restrictive lung disease
Restrictive lung disease, on the other hand, involves reduced lung capacity, making it harder to take a full breath. This happens when the lungs can’t expand properly, often due to stiffened lung tissue, weakened respiratory muscles, or chest wall abnormalities — seen in conditions like pulmonary fibrosis, sarcoidosis, and scoliosis.
Spirometry helps detect restrictive lung disease by measuring your total lung capacity (FVC). A reduced FVC, combined with a normal or high FEV1/FVC ratio, signals a restriction, allowing healthcare providers to differentiate it from obstructive diseases and tailor a suitable management plan.
Spirometry is an important procedure to check if your lungs are functioning properly and detect any potential lung diseases that you may have so that you are able to discuss the proper treatment plans necessary as soon as possible.
If you suspect you have severe breathing issues or a potential lung disease, consult your healthcare provider to determine the next steps for evaluation and treatment. Request an appointment with our lung specialists at Thomson Medical today.
FAQ
What does a spirometry test tell you?
Spirometry provides information about your lung capacity and how quickly you can move air in and out of your lungs. This information helps diagnose conditions like asthma and COPD and monitor the progression of lung diseases.
What is a normal spirometry level?
Normal spirometry results vary based on age, height, sex, and race. Generally, a normal FEV1/FVC ratio is around 70-80% for adults.
Can spirometry detect pneumonia?
While spirometry can detect airflow limitations, it's not typically used to diagnose pneumonia. Other tests, like chest X-rays, are more commonly used for pneumonia diagnosis.
Why would a doctor order a spirometry test?
Doctors order spirometry tests to diagnose respiratory conditions, monitor existing lung diseases, assess pre-operative lung function, or screen for occupational lung disorders.
How accurate is spirometry?
When performed correctly, spirometry is highly accurate. However, the test's reliability depends on the patient's effort and proper technique.
Can you fix weak lungs?
While you can't necessarily "fix" weak lungs, you can improve lung function through exercises, quitting smoking, and proper management of respiratory conditions under medical supervision.
The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.
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