Spirometry Test: Essential Tool for Diagnosing Asthma

Asthma is a condition that affects breathing, causing symptoms like wheezing, shortness of breath, and chest tightness. Accurate diagnosis and ongoing management is important to help people live well with asthma. Spirometry is a simple test that measures how well your lungs work and is essential in diagnosing and managing asthma. It measures how much air you can breathe in and out, helping doctors understand your respiratory health.

This article delves into the workings of spirometry, its significance in asthma care, the testing process, and the interpretation of results. Knowing what to anticipate can ease any concerns and help you better understand your symptoms, leading to more effective treatment and improved quality of life.

What is a Spirometry Test?

Definition and Purpose

Spirometry is a non-invasive test that measures how much air and how fast you can breathe in and out.  It provides objective data on lung function, essential for identifying airflow limitations characteristic of asthma.This helps your healthcare providers tailor treatment plans more effectively.

How Spirometry Works 

Spirometry measures lung function by assessing airflow and lung volumes. During the test, the patient breathes into a spirometer, which records how much air and how quickly it is inhaled and exhaled.

Key measurements taken during the test include:

• Forced Expiratory Volume in one second (FEV1): the volume of air that can be forcibly exhaled in the first second.

• Forced Vital Capacity (FVC): the total volume of air forcefully exhaled after a full inhalation.

• FEV₁/FVC Ratio: Compares FEV₁ to FVC to detect airflow obstruction.
  
  

Spirometry is recommended for all patients with suspected asthma to confirm the diagnosis and assess the severity of airflow limitation.

The Role of Spirometry in Diagnosing Asthma

Why Spirometry is Essential

Asthma diagnosis involves a combination of clinical assessment and objective testing. Spirometry provides objective data that helps doctors confirm asthma by: 

• Detecting Obstruction: A low FEV₁/FVC ratio suggests asthma.

• Checking Reversibility: If your FEV₁ improves by 12% or more after a bronchodilator, it supports an asthma diagnosis.
  
  

It also helps differentiate asthma from other similar conditions, ensuring that patients receive the correct diagnosis and treatment. Regular spirometry tests also track asthma progression and treatment effectiveness.

When is Spirometry Recommended?

It is recommended for patients with symptoms that may suggest asthma or other lung conditions.

Spirometry is often recommended in the following instances:

• Investigate unexplained respiratory symptoms.

• Confirm an asthma diagnosis and monitor lung function.

• Assess response to bronchodilators or other treatments.

• Track progression of chronic lung conditions.
  
  

Beyond diagnosis, periodic spirometry can also help you and your healthcare providers with ongoing asthma management: 

• Monitoring disease progression: Regular spirometry tests help track lung function over time, identifying any decline that might indicate poor asthma control.

• Guiding treatment adjustments: Objective measurements inform healthcare providers when to modify treatment plans to achieve optimal asthma control.

• Evaluating treatment efficacy: Spirometry assesses the effectiveness of prescribed therapies, ensuring you receive the most appropriate care.
  
  

While spirometry is a safe test, it is not recommended in certain conditions. So it is important to let your doctor or the nurse know if you have recently had any of the following: 

• An active respiratory infection

• Coughing of blood

• History of collapsed lung

• A recent heart attack 

• History of an aneurysm 

• Recent operation on your eye, head, abdomen or chest
  
  

Inform the nurse if you have coughed up blood in the past 48 hours or if your doctor thinks you may have tuberculosis, influenza or a respiratory infection. 

What to Expect During a Spirometry Test

Preparation for the Test

Proper preparation is important for accurate test results. Patients should follow these guidelines:

• Follow your healthcare provider’s instructions regarding whether to take your inhalers or pause certain medications before the test

• Refrain from drinking alcohol or other intoxicants for at least 8 hours before the test 

• Do not eat large meals 4 hours before the test

• Avoid smoking for at least 1 hour before the test

• No heavy exercise for at least 1 hour before the test

• Wear comfortable, unrestrictive clothing for the test

• Go to the toilet right before the test
  
  

Steps Involved in the Test 

• The nurse will explain the procedure and answer any questions you may have.

• You will receive a sterile mouthpiece connected to the spirometer for breathing.

• You will be instructed to inhale deeply and then exhale forcefully and quickly. This may be repeated at least three times for accurate results.

• The nurse will monitor your performance and provide guidance throughout the test.

• In some instances your doctor may wish to assess the reversibility of your lung condition, and will require you to have some bronchodilator after the first measurements, which will be followed by a second round of measurements 15 minutes later.

• The recorded lung function data will be reviewed by your doctor.

• A spirometry usually takes approximately 20–30 minutes. It is not difficult or painful but requires some effort.

Bringing Your Inhaler to the Test

Patients are advised to bring their inhaler to the spirometry test. This is important because it may be used during the test to evaluate the effectiveness of bronchodilators in improving lung function, providing valuable information for treatment adjustments.

Spirometry for Children Aged 6 and Above 

Spirometry is suitable for children aged 6 and older. The test is adjusted to ensure comfort and understanding for younger patients. Early diagnosis through spirometry can lead to better asthma management, improving long-term health outcomes.

Interpreting Spirometry Results 

Understanding the Parameters

Spirometry measures important lung function indicators that help assess your respiratory health. Here are the key parameters:

• Forced Expiratory Volume in one second (FEV1): This shows how much air you can blow out in one second. A lower number can signal that your airways might be narrowed.

• Forced Vital Capacity (FVC): This measures the total amount of air you can exhale after taking the deepest breath possible.

• FEV1/FVC Ratio: This ratio compares the FEV1 to the FVC. A low ratio indicates airflow obstruction, which is often seen in conditions like asthma.

Normal vs. Abnormal Results

Spirometry results are compared to predicted normal values based on age, gender, height, and ethnicity. Understanding spirometry results is important for assessing lung health:

• Normal Results: FEV1 and FVC within expected ranges, with an FEV1/FVC ratio above the lower limit of normal Indicate no airflow limitation or obstruction. 

• Obstructive Pattern (Abnormal): Reduced FEV₁/FVC ratio suggests airflow obstruction, characteristic of asthma or COPD. When there is an improvement in FEV₁ or FVC after bronchodilator administration it is called a reversible airflow obstruction, which supports a diagnosis of asthma.

• Restrictive Pattern (Abnormal): Increase FEV₁/FVC ratio suggests reduced ability of the lungs to expand and can be seen in Lung Fibrosis or Congestive Cardiac Failure.
  
  

If the  results are abnormal, your healthcare provider may recommend further testing or adjustments to your treatment plan.

Spirometry and Asthma Management 

Monitoring Asthma Control

By regularly measuring lung function, your healthcare provider can determine how well your asthma is managed and if your treatment plan needs adjustments. These tests help identify any changes in your symptoms, allowing for timely interventions.

Regular spirometry tests can help track improvements or declines in lung function, ensuring that your medications are effective. Staying on top of your asthma management with these tests can lead to fewer symptoms and better overall health. Always discuss your spirometry results with your doctor to optimise your treatment plan.

Benefits of Spirometry in Long-Term Management 

Incorporating spirometry into your long-term asthma management plan offers valuable benefits:

• Regular lung function tests help you and your doctor track your asthma symptoms more effectively.

• By identifying changes in lung function early, you can make timely adjustments to your treatment and reduce the risk of severe asthma attacks.

• Spirometry results allow your healthcare provider to tailor your medications to fit your needs, ensuring optimal care.

• Knowing your lung health helps you make informed decisions, giving you more control over your asthma.
  
  

Post-Spirometry Steps

What Happens After a Spirometry Test? 

After a spirometry test, patients may discuss the results with their healthcare provider. Follow-up tests, such as chest scans or additional pulmonary function tests, may rarely be recommended based on the initial findings to further evaluate respiratory health.

How Spirometry Test Results Help Healthcare Providers

The results from a spirometry test provide healthcare providers with essential data for diagnosing asthma and determining its severity. It also helps them monitor your condition and assess your asthma control. This information is crucial for creating personalised treatment plans that effectively address the patient’s respiratory health.

Where can I get a Spirometry Test done?