Breathing tests: measuring the lungs instead of guessing at them.
You cannot tell how well someone's lungs are working by listening to them, and you cannot diagnose asthma from symptoms alone. These are the tests that turn an impression into a number — what each one is, what it feels like, and what the result actually means.
- Spirometry is the main one. You blow hard into a tube. It takes about 20 minutes and tells us whether the airways are narrowed, and whether that narrowing opens up with medicine.
- None of these tests hurts. The worst of it is feeling briefly out of breath or light-headed after blowing hard.
- Asthma should not be diagnosed, or a lifelong inhaler started, without an objective test. That is the single most important sentence on this page.
- Some tests are done here in the clinic. Others — CT scans, bronchoscopy, a full overnight sleep study — are arranged elsewhere, and we say so plainly.
Why it matters
Symptoms are a poor guide
A great many people in India are carrying an asthma label that was never confirmed, and a great many others have asthma that has never been named. Both happen for the same reason: the diagnosis was made from the story alone.
Breathlessness can come from asthma, from COPD, from a heart that is not pumping well, from anaemia, from anxiety, from obesity, from deconditioning, or from lungs scarred by tuberculosis years ago. These are treated completely differently. A cough that has lasted three months is not one disease.
The American Academy of Allergy, Asthma & Immunology puts it bluntly in its Choosing Wisely list: don't diagnose or manage asthma without spirometry. Symptoms and physical examination alone both over-diagnose and under-diagnose it. If you have been on an inhaler for years and have never blown into a machine, that is worth correcting — sometimes the answer is that you can stop.
What we do, and how long each takes
Everything in this table is explained in plain terms further down the page.
| Test | What it measures | Time | Where |
|---|---|---|---|
| Spirometry | How much air you can blow out, and how fast — the standard test for airway narrowing | 15–20 min | Here |
| Bronchodilator reversibility | Whether that narrowing opens up after a reliever inhaler — the test that distinguishes asthma from fixed obstruction | +20 min | Here |
| Peak flow monitoring | Day-to-day variation in your breathing, recorded at home over two weeks | At home | Here |
| Pulse oximetry | Oxygen saturation in the blood, from a clip on the finger | 1 min | Here |
| Exhaled carbon monoxide | Smoke exposure, as a number — used in the quit programme | 2 min | Here |
| Six-minute walk test | How far you can walk in six minutes and whether your oxygen falls — real-world capacity, not lab capacity | 20 min | Here |
| FeNO (exhaled nitric oxide) | Allergic inflammation in the airway, which helps predict who will respond to an inhaled steroid | 5 min | Referred |
| Full lung function with DLCO | Total lung volumes and gas transfer — for scarring, emphysema and pre-operative assessment | 45 min | Referred |
| Chest X-ray and CT | Structure: infection, scarring, bronchiectasis, nodules | Same day | Referred |
| Sleep study (polysomnography) | Breathing pauses, oxygen dips and sleep quality overnight | Overnight | Referred |
| Bronchoscopy / EBUS | Direct view inside the airway, with biopsy where needed | Day case | Referred |
"Referred" means we arrange it at a hospital or laboratory we work with, and interpret the result with you afterwards. Dr. Radhika performs bronchoscopy, EBUS and pleural procedures in hospital practice; they are not done in a consulting room anywhere.
Spirometry
What it actually feels like
You sit down. A soft clip goes on your nose so no air escapes that way. You take the deepest breath you possibly can, seal your lips around a clean disposable mouthpiece, and blow out as hard and as fast as you can — and keep blowing until you are told to stop, usually about six seconds. It feels like blowing out every candle on a birthday cake at once, and then going on longer than feels natural.
You will be asked to do it at least three times, because the test only counts if the results agree with each other. Being urged on loudly is normal and is part of the technique, not a sign anything is wrong.
Most people find the effort tiring rather than unpleasant. Some feel light-headed or cough afterwards. Both settle within a minute or two. If you have had recent chest, eye or abdominal surgery, a heart attack in the last month, or a collapsed lung, tell us before we start — spirometry is delayed in those situations.
If there is narrowing, we then give four puffs of salbutamol through a spacer and wait fifteen minutes, and you blow again. If the numbers improve substantially, that reversibility is the fingerprint of asthma. If they do not, it points towards COPD or fixed disease — a different diagnosis with a different treatment.
Preparing
Before you come for spirometry
- Withhold your reliever inhaler — salbutamol or levosalbutamol — for 4 to 6 hours, if you can do so safely. If you need it, take it and tell us; we will note the time rather than cancel.
- Long-acting inhalers — formoterol, salmeterol, tiotropium and the combinations — need 12 to 24 hours. We will tell you which applies when you book.
- Do not smoke for at least an hour beforehand, and avoid a heavy meal in the two hours before.
- Wear something loose. Tight clothing around the chest and waist genuinely changes the result.
- Bring your inhalers in the bag, all of them, including the ones you have stopped using. We will check your technique — and a surprising proportion of "treatment failure" turns out to be inhaler technique.
- No alcohol for four hours before.
Results
What the numbers mean
You will see three figures on the printout, and you will be walked through all of them before you leave.
FEV1 is the volume of air you blow out in the first second. It is the number that falls when airways narrow, and the one we track over time.
FVC is the total volume you can blow out. The FEV1/FVC ratio is the two compared — and it is the ratio, not either number alone, that separates an obstructive pattern (asthma, COPD) from a restrictive one (scarring, chest wall or muscle problems, sometimes obesity).
Each result is compared against predicted values for someone of your age, height, sex and ethnicity. This matters more in India than is usually acknowledged: using European reference equations for Indian patients systematically misreads normal lungs as abnormal. We use appropriate reference values and will tell you which.
A normal spirometry does not always exclude asthma. If you are well on the day of the test, the airways may be open and the reading normal. That is why peak flow diaries over two weeks, and sometimes a trial of treatment with repeat testing, are used — and why we may ask you to come back rather than declare the matter closed.
Other tests
Briefly, the rest
Peak flow at home. A small handheld meter, blown into morning and evening for two weeks, with the readings written on a chart. Asthma characteristically swings — worse at night and early morning, better by midday. That swing is often more revealing than a single clinic test, and the meter costs very little.
Pulse oximetry. A clip on the finger for a minute. Below 94% at rest needs explanation. Nail polish, cold hands and, notably, darker skin tones can all affect the reading, so it is interpreted alongside everything else and not treated as the whole story.
The six-minute walk test. You walk up and down a measured corridor for six minutes at your own pace, stopping if you need to, with oxygen saturation measured before and after. It answers the question a lab test cannot: what happens when you actually move. Useful in COPD, in scarred lungs, in post-TB disease, and before starting pulmonary rehabilitation.
FeNO. A slow, steady blow into a handheld analyser measures nitric oxide in the breath. A high level indicates the specific type of inflammation that responds to inhaled steroids. It is most useful in children and in adults where the picture is unclear — and it is one of the few tests that can show a patient their inflammation as a number rather than a reassurance.
Exhaled carbon monoxide. Two minutes, one breath held for fifteen seconds. It shows a smoker their exposure as a figure that falls within a day of stopping. It will not detect gutkha, khaini or other smokeless tobacco — which is precisely why smokeless use so often goes unmeasured and unaddressed.
- Done here: spirometry with reversibility, peak flow, pulse oximetry, six-minute walk, exhaled carbon monoxide, skin prick testing
- Arranged elsewhere and interpreted with you: FeNO, full lung function with DLCO, chest X-ray and CT, sleep studies, allergen challenge testing
- Done in hospital by Dr. Radhika: bronchoscopy, EBUS and pleural procedures
What patients ask
Does spirometry hurt?
No. It is effort, not pain. The commonest reactions are a cough, a moment of light-headedness, or tiredness after the third attempt. All settle in a minute or two, and you can rest between blows for as long as you need.
My child is six. Can they do it?
Usually yes, from about five or six, with coaching — the software has games that turn the blow into candles going out or a balloon inflating. Under five it is rarely reliable, and we rely on history, examination, FeNO where available, and a carefully monitored trial of treatment instead.
I've been on an inhaler for eight years and never had a test. Is it too late?
Not at all, and it is worth doing. Spirometry after years of treatment still tells us whether there is obstruction, whether it reverses, and whether your current dose is right. Some people are on more treatment than they need. A few turn out never to have had asthma. Bring every inhaler you have used.
I finished TB treatment and I am still breathless. Is that normal?
It is common and it is under-recognised. Being cured of the infection does not mean the lungs returned to normal — scarring, airway narrowing and bronchiectasis can all persist, and this is well described in Indian studies of patients who have completed treatment. Spirometry after treatment completion is worth doing, and there is a good deal that helps: bronchodilators where there is obstruction, pulmonary rehabilitation, vaccination, and treatment of any co-existing disease.
Do I need to fast?
No. Avoid a heavy meal in the two hours before, but come having eaten normally otherwise.
Will I get the results the same day?
Yes. Spirometry is read and explained during the same appointment, and you leave with the printout and a written explanation of what it shows.
Book a breathing assessment
Bring your inhalers, any earlier spirometry or X-ray reports, and a list of your medicines. Reports can be sent on WhatsApp before you come.
Sources
American Academy of Allergy, Asthma & Immunology — Choosing Wisely recommendation: "Don't diagnose or manage asthma without spirometry."
Asthma + Lung UK — patient information on spirometry, peak flow, FeNO and the six-minute walk test.
Global Initiative for Asthma (GINA) and Global Initiative for Chronic Obstructive Lung Disease (GOLD) — diagnostic criteria and reversibility thresholds.
Indian studies of post-tuberculosis lung disease, including spirometry assessment at treatment completion.
This page is general information and does not replace an individual consultation.