PFT (Pulmonary Function Test)
A focused scan for Lung volumes, Airflow, Asthma and more.
Overview
Examines Lung volumes, Airflow, Asthma, COPD. Performed at an NABL-accredited Meridian Health centre with a same-day report and a free doctor review.
The full panel
4 areas across 1 groupEvery parameter, grouped by body system — no clicking to expand.
What this scan measures
How much air your lungs can move and how fast. You blow as hard and as long as you can into a mouthpiece, and spirometry records the forced vital capacity (FVC), the volume blown out in the first second (FEV1), the ratio between them, and the peak and mid-flow rates. A bronchodilator is often given and the test repeated to see whether the obstruction reverses.
It is the objective test for asthma and COPD, distinguishing them from each other and from restrictive lung disease. It is also used to assess breathlessness of unclear cause, to monitor known lung disease, to check response to inhalers, and to assess fitness before surgery.
Symptoms that lead to this scan
- Breathlessness on exertion or at rest
- Chronic cough or wheeze
- Chest tightness, particularly at night or in the early morning
- Known asthma or COPD needing objective assessment
- Occupational dust or fume exposure, or long-term smoking
Understanding your results
A reduced FEV1/FVC ratio describes an obstructive pattern, most commonly asthma or COPD; a proportionate reduction in both with a preserved ratio suggests a restrictive pattern, which points towards the lung tissue, the chest wall or the muscles rather than the airways. A significant improvement in FEV1 after a bronchodilator indicates reversible obstruction, which is characteristic of asthma but not exclusive to it. Results are always expressed against predicted values for your age, height, sex and ethnicity — and the test is entirely effort-dependent, so a poor technique produces a falsely abnormal result rather than a real one.
Indicative only. Reference ranges vary between laboratories and between testing methods, and shift with age, sex and pregnancy — always read your own result against the range printed on your own report, with the doctor who ordered it.
| Parameter | Indicative range | Unit |
|---|---|---|
| FEV1/FVC ratio | 0.70 or above (a fixed cut-off; lower limit of normal is age-adjusted) | ratio |
| FEV1 | 80–120 of predicted | % predicted |
| FVC | 80–120 of predicted | % predicted |
| Bronchodilator reversibility | A rise of 12% and 200 mL in FEV1 is considered significant | change |
Why the preparation matters
Withhold short-acting inhalers for around 6 hours and long-acting ones for longer if — and only if — your doctor has told you to; the point is to measure your lungs without treatment on board so that reversibility can be assessed, but never stop regular treatment on your own. Avoid a heavy meal, smoking and vigorous exercise beforehand, wear loose clothing that does not restrict the chest and abdomen, and do not wear lipstick or anything that stops a firm seal on the mouthpiece. Expect to repeat the manoeuvre several times: at least three technically acceptable, reproducible efforts are needed before a result can be reported.
Pulmonary — safety and who should not be scanned
Full Pulmonary guideThere is no radiation, no injection and nothing to swallow — a lung function test only measures your own breathing, and it can be repeated as often as it is useful. The forced manoeuvre does raise the pressure inside the chest, the abdomen and the head sharply for a few seconds, and that is the reason the test is postponed after certain recent events rather than simply performed regardless. Feeling light-headed or coughing after a maximal blow is common and settles within a minute; tell the technician and they will let you recover fully before the next effort. Where imaging is done alongside the function test — a chest X-ray or a CT — that component carries its own radiation dose, described on those pages.
- Pregnancy
- Spirometry itself involves no radiation, though a full forced manoeuvre in late pregnancy is often uncomfortable and less reliable. What matters is the imaging that frequently accompanies a respiratory workup: a chest X-ray or CT is deferred, shielded or replaced in pregnancy, and that decision is made by a doctor. Declare a pregnancy or the possibility of one when you book the appointment.
- A recent collapsed lung, or recent surgery
- The forced blow raises pressure inside the chest, the abdomen and the skull for several seconds, so the test is deferred after a pneumothorax and after surgery to the chest, abdomen or eye — commonly for at least a week, and longer after brain surgery. The exact interval is set by the doctor who requested the test, and it is a postponement rather than a refusal.
- Recent heart attack, unstable chest pain or a known aneurysm
- The same pressure change is the reason. A recent myocardial infarction, chest pain that is unstable, an uncontrolled rhythm disturbance, a recent pulmonary embolus not yet anticoagulated, or a known aneurysm in the chest, abdomen or brain all mean the test waits until the situation is stable. Mention any of these when booking rather than at the mouthpiece.
- Coughing blood, or an active chest infection
- Haemoptysis of unknown cause can be made worse by a forced manoeuvre, and an active transmissible chest infection — tuberculosis in particular — is aerosolised by it. The test is postponed until the cause is known or the infection is controlled, and where it must go ahead it is done with infection-control precautions and dedicated filters.
- Being unable to perform or sustain the manoeuvre
- A good seal on the mouthpiece and a sustained maximal effort are what the whole test rests on. Facial weakness, a recent stroke, severe breathlessness at rest, marked hearing impairment, confusion or dementia may make a reliable result impossible — and a poor technique yields a falsely ABNORMAL result rather than no result at all, which is the more dangerous outcome. Say so beforehand so a different assessment can be arranged.
- Contrast, where the workup includes a CT
- A CT pulmonary angiogram — the scan used when a clot on the lung is suspected — uses iodinated contrast, so kidney function, any previous contrast reaction and your medication list are all checked first, exactly as for any contrast CT. The function test itself needs none of this.
Who should consider this scan
- Anyone with unexplained breathlessness, wheeze or chronic cough
- People with known asthma or COPD, for monitoring
- Smokers and ex-smokers over 40
- Workers with dust, fume or chemical exposure
- Patients being assessed before major surgery
Conditions it helps detect
How it works
Patient stories
96% recommend“The phlebotomist arrived exactly on time and was gentle. My report came in five hours with a doctor’s note.”
“Booked at night, sample collected next morning. The parameter breakdown is genuinely thorough.”
“Loved the free doctor review — she walked me through my vitamin D and thyroid results clearly.”