15467 Body Plethysmography Pulmonary Function Test

Overview

Body plethysmography (say: pleh-thiz-MOG-ruh-fee) is a breathing test that measures how much air your lungs can hold and how easily air moves in and out. You sit inside a small, clear, sealed booth — often called a 'body box' — and breathe through a mouthpiece while a computer records the pressure changes around you. Unlike simpler breathing tests, it can measure the air that stays in your lungs even after you breathe out as hard as you can. That leftover air is called residual volume, and knowing it helps your doctor understand how your lungs are working.

Yes. Body plethysmography is a standard, widely used lung function test in hospitals and specialist lung clinics around the world. It is one of the routine breathing tests used for many thousands of people every year.

Symptoms

Common symptoms

• Shortness of breath, especially when walking, climbing stairs or exercising
• A cough that keeps coming back or does not clear up
• Wheezing (a whistling sound when you breathe)
• Chest tightness or a feeling of not being able to get a full breath
• Tiring more easily than usual with everyday activity
• Coughing up phlegm (spit) regularly
• Frequent chest infections

Symptoms in children

• Breathing faster than usual or working hard to breathe
• Wheezing or noisy breathing, especially with colds or exercise
• A cough that lingers for weeks
• Tiring quickly during play or PE at school
• Poor weight gain or slower growth in some long-term lung conditions
• Repeated chest infections

Symptoms in older adults

• Getting out of breath doing things that used to feel easy, such as dressing or walking to the shops
• A long-standing 'smoker's cough' or a cough that has changed
• Reduced stamina and needing to stop to catch your breath
• Symptoms blamed on 'just getting older' that may actually be a lung problem worth checking
• Breathlessness alongside other conditions such as heart disease, which your doctor may want to tell apart

Causes

Main causes

• This is a test, not an illness, so it has no 'causes' in the usual sense. It is used to look into the reasons behind breathing symptoms.
• Asthma — the airways become inflamed and narrow, often coming and going
• COPD (chronic obstructive pulmonary disease) — long-term damage to the airways and air sacs, most often from smoking
• Scarring or inflammation of the lung tissue (for example pulmonary fibrosis or other interstitial lung diseases)
• Cystic fibrosis and bronchiectasis — conditions where mucus builds up and airways widen
• Weakness of the breathing muscles, or a chest shape that limits how fully the lungs can fill
• Checking lung function before surgery, or monitoring a known lung condition over time

Risk factors

• Smoking or long-term exposure to second-hand smoke
• Working with dusts, fumes or chemicals without good protection
• Living in areas with high air pollution
• A family history of lung disease or asthma
• Premature birth or frequent chest infections in childhood
• Being overweight, which can make breathing more effortful
• Some jobs such as mining, construction, farming or welding

When to see a doctor

See a doctor urgently if:

• You are coughing up blood
• You have chest pain along with breathlessness
• Your breathing has become much worse over a short time
• You have a fever and feel very unwell with a new cough
• A child is breathing fast, sucking in at the ribs, or seems very sleepy

Book a routine appointment if:

• You get out of breath more easily than you used to
• You have a cough lasting more than three weeks
• You wheeze or have tightness in your chest
• You have had several chest infections in a year
• Your doctor has suggested a lung function test and you want to understand what it involves

Diagnosis

Body plethysmography is itself a diagnostic test — it is one of the tools your doctor uses to work out what is going on, rather than something used to diagnose the test. Your doctor will usually ask about your symptoms and history, examine you, and then arrange breathing tests. The results are read together with your symptoms, your medical history and other tests. No single test gives all the answers.

Tests that may be done

• Body plethysmography (lung volumes and airway resistance)
• Spirometry — blowing hard into a tube to measure how fast and how much air you can breathe out
• Gas transfer test — measures how well oxygen moves from your lungs into your blood
• Peak flow readings, sometimes recorded at home over a few weeks
• A chest X-ray or CT scan if your doctor needs to look at the lung tissue
• Blood tests, including one that measures oxygen and carbon dioxide levels
• Allergy tests if asthma is suspected

What to expect at your appointment

You will be shown into a small, clear booth that looks a bit like a phone box or a shower cubicle. You sit inside, a soft clip goes on your nose, and you breathe through a mouthpiece. The door closes and the technician can see and hear you the whole time. You will do a few sets of quick, shallow 'panting' breaths, and at times a small shutter briefly blocks the mouthpiece while you keep panting — this lasts only a second or two. You may also be asked to breathe out fully and then take a deep breath in. It is not painful, but you may feel a little out of breath or worried about being in a small space. Tell the technician if you feel uneasy — the door can be opened immediately and the test paused at any point.

Treatment

The test does not treat anything itself — its job is to give your doctor clear information so the right treatment can be chosen. Once your results are back, your doctor will explain what they show and discuss options with you. Treatment is then aimed at the condition found, with the goal of helping you breathe more easily, stay active and avoid flare-ups.

Self-care at home

• Follow any preparation instructions your clinic gives you — for example, avoiding smoking for 24 hours before the test
• Avoid a heavy meal just before the appointment, and avoid alcohol on the day
• Wear loose, comfortable clothing that does not press on your chest
• Bring your inhalers or other breathing medicines with you, even if you are not due to use them
• Do not stop or change any medicine unless your own doctor or the clinic has told you to
• Tell the technician if you are or might be pregnant, feel claustrophobic, have recently had a heart attack or chest surgery, or have a collapsed lung
• Arrange for someone to come with you if you feel anxious in small spaces
• After the test, you can eat, drink and go about your normal day

Medical treatments

Treatment depends entirely on what the test shows. If asthma is found, the focus is usually on preventer and reliever inhalers, a written action plan and learning your triggers. If COPD is found, treatment may include inhaled medicines, help to stop smoking, pulmonary rehabilitation (a supervised exercise and education programme) and vaccinations. For scarring of the lungs or other conditions, your specialist team will discuss monitoring and specific therapies. Oxygen therapy at home is used for some people with low blood oxygen. Your doctor will always explain why a treatment is being offered, what it is expected to do and what side effects to watch for.

When is surgery considered?

Surgery is not part of body plethysmography. Sometimes the test is done before an operation — for example lung surgery or major abdominal surgery — to help the surgical team judge how well your lungs are likely to cope. If your results suggest a higher risk, your team will talk through the benefits and risks with you and plan extra support around the operation.

Living with this condition

Once you know your results, day-to-day life usually becomes clearer rather than harder. You will know what your lungs are doing, what to do if symptoms change, and which treatments help. Keep your appointments for repeat tests — comparing results over time is often more useful than a single reading. If you use inhalers, keep them where you can reach them and check you are using the right technique; your pharmacist or nurse can watch you use it and correct your technique.

Lifestyle tips

• If you smoke, stopping is the single biggest thing you can do for your lungs — ask your doctor or pharmacist for support, which works best when combined with coaching
• Keep active with walking, cycling or swimming at a level that suits you
• Avoid smoky rooms, strong fumes, and burning incense or open fires indoors without good ventilation
• Keep rooms well ventilated and follow air quality alerts on very polluted days
• Keep your home warm and damp-free; cold, damp air can worsen breathing symptoms
• Have a written action plan for flare-ups and keep emergency contact details handy

Diet and exercise

Eating well and moving regularly both help your lungs work better. Aim for regular meals with plenty of vegetables, fruit, wholegrains, beans and lean protein, and keep well hydrated — thin mucus is easier to cough up. If you are underweight or overweight, ask your doctor for advice, as both can affect breathing. For exercise, start gently and build up. Breathing exercises, pursed-lip breathing and paced activity can help you feel less breathless. A pulmonary rehabilitation programme is a safe, supervised way to build fitness if you have a long-term lung condition.

Mental health and emotional wellbeing

It is very common to feel anxious or low when you are breathless or waiting for test results. Breathlessness and anxiety can feed each other, so learning slow breathing and relaxation techniques can genuinely help. Feeling worried does not mean you are coping badly — it is a normal response. Tell your doctor if these feelings are affecting your sleep, appetite or daily life, because talking therapies and support groups can make a real difference. If you ever feel you cannot cope or have thoughts of harming yourself, contact your local emergency number or a crisis line in your country straight away.

Prevention

You cannot 'prevent' a lung function test — it is a check, not an illness. What you can do is protect your lungs so that problems are less likely in the first place: avoid smoking and second-hand smoke, use proper protective equipment at work, keep up with vaccinations, and get breathlessness or a lasting cough checked early rather than putting it down to age.

Vaccines

Ask your doctor or pharmacist which vaccinations are recommended for you. People with long-term lung conditions are often advised to have yearly flu vaccination, pneumococcal vaccination and COVID-19 vaccination according to national guidance. Vaccination reduces the risk of chest infections that can cause flare-ups.

Screening programmes

There is no routine screening programme that uses body plethysmography. It is arranged when you have symptoms, when you have a known lung condition that needs monitoring, or before certain operations. If you are a current or former smoker with breathing symptoms, speak to your doctor about whether lung function testing is right for you.

Complications

If left untreated

• Breathing problems that are not assessed can slowly get worse before they are noticed
• A treatable condition such as asthma may go undiagnosed, leading to avoidable flare-ups
• Lung damage from smoking or workplace dust may continue unnoticed
• Repeated chest infections may weaken the lungs further over time
• Breathlessness that is not explained can cause worry, poor sleep and reduced activity, which in turn lowers fitness

Long-term outlook

The outlook is generally good. Body plethysmography is a safe, well-established test, and most people find it easier than they expected. Its real value is in giving you and your doctor clear information, so that whatever is found can be treated early and managed well. Many lung conditions are now controlled effectively, and most people with a lung diagnosis go on to live full, active lives with the right support.

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