Spirometry Taree

Spirometry measures two key values. FVC (forced vital capacity) is the total amount of air you can forcefully exhale after your deepest breath, and FEV1 (forced expiratory volume in one second) is how much of that air you can push out in the first second. Comparing these values against each other and against predicted values for your age, height and sex shows whether your breathing is normal, obstructed or restricted.

An obstructive pattern, where air flows out more slowly than expected, is typical of asthma and COPD. A restrictive pattern, where the lungs hold less air than expected, points towards different conditions affecting lung expansion. The bronchodilator comparison adds further information: significant improvement after medication suggests asthma, while limited improvement is more consistent with COPD. Spirometry results are interpreted alongside your symptoms and history rather than in isolation, and your doctor explains what your numbers mean at the appointment.

The most common reasons are investigating unexplained breathing symptoms and monitoring known lung conditions. Persistent cough, breathlessness during everyday activity, wheezing or chest tightness all warrant lung function assessment, particularly in smokers and former smokers, where spirometry is the key test for detecting COPD, a condition that often develops gradually and goes unnoticed until significant function is lost.

For people with diagnosed asthma or COPD, periodic spirometry tracks whether the condition is stable, improving or progressing, and whether current medications are doing their job. Doctors also order spirometry to assess lung function before certain surgeries, to investigate occupational exposure to dusts or chemicals and to evaluate breathing capacity in people with conditions that can affect the lungs over time. Because the test is quick and non-invasive, it's often part of the initial workup rather than a last resort.

Follow the specific instructions given when you book, as they vary depending on why the test is being done. The most important instruction usually concerns inhalers: if the test includes a bronchodilator response assessment, you may be asked to withhold reliever inhalers for several hours and certain preventers for longer, because using them beforehand can mask the response the test is designed to measure. Never stop medications without being instructed to, and take your usual inhalers with you to the appointment.

General preparation is simple. Avoid smoking for at least an hour before the test (longer is better), skip vigorous exercise for 30 minutes beforehand, avoid large meals in the preceding two hours and wear loose, comfortable clothing that doesn't restrict your chest. Arrive a few minutes early so you're rested rather than breathless from rushing. If you're unwell with a cold or chest infection on the day, call ahead, as the test may need rescheduling to give accurate results.