How much air do we breathe?

People with healthy lungs breathe in around 11,000 litres of air every day. That’s enough air to fill 5,500 large bottles of lemonade. 

What do our lungs do?

Our lungs help us breathe in oxygen and get rid of carbon dioxide. They also act as a defence against infection and harmful environmental factors, such as dust, smoke and pollen. 

Our lungs transport oxygen into the bloodstream to keep body tissues and cells healthy. Having fit and healthy lungs means that oxygen gets to body tissues much more easily. Sometimes when people’s lungs are not working properly they can have low blood oxygen levels, and they are given oxygen to help resolve this. 

Our noses act as the first defence against harmful materials that we inhale, such as smoke, pollution and bacteria, and our lungs offer a second. Lungs have sticky mucus that traps microbes and helps their protective white blood cells (phagocytes) to swallow and kill bacteria and destroy harmful materials. Lungs also have tiny, brush-like fibres, known as cilia, to keep our airways clear. 

When people with an immunodeficiency disease have an infection, it can make them more susceptible to problems with their lungs.  

What can happen to my lungs when I keep getting infections?

When you get lots of infections and inflammation, it can permanently enlarge the airways. This is known as bronchiectasis (pronounced “bron-key-ect-a-sis”). This causes the airways to become dilated, inflamed and easily collapsible. Also, the cilia (brush-like fibres) don’t work as well, so you can’t clear away microbes (bacteria, fungi and viruses) as efficiently. Bronchiectasis can be diagnosed using a CAT scan (X-rays that build up a layer-by-layer picture of tissues in your body). 

Sometimes scar tissue (also called “pulmonary fibrosis”) can build up in the lungs and this reduces how effective they are at transporting oxygen to red blood cells. 

Why can’t I breathe properly when I get pneumonia or a chest infection?

Having an infection such as pneumonia is serious because it makes it harder for your lungs to absorb oxygen from the air you breathe. Also, more of the blood gets diverted to the parts of the lungs which are affected by the infection. 

Why is it vital to keep your lungs as healthy as possible when you have an immunodeficiency?

To prevent them deteriorating, by limiting damage caused by infection and inflammation. 

How do I keep my lungs healthy?

Here are some key things that will help: 

  • Don’t smoke or vape and avoid breathing in second-hand smoke. 
  • Help prevent infection by keeping up to date with vaccinations, including the seasonal flu vaccination. 
  • Take the medicines given by your doctor regularly and as recommended. 
  • Know the signs of a chest infection.
  • Take regular exercise. 
  • Always get advice if you are worried; ask your doctor if you should see a chest specialist. 
  • Discuss with your healthcare professional whether you should have a test of your lung function.

What are the symptoms of a lung infection?

Symptoms are: 

  • a persistent cough 
  • breathlessness 
  • producing sputum or phlegm (mucus that you might cough up from the airways). 

Always seek help when you have any of the above symptoms. Getting early treatment could reduce damage to your lungs. 

Why is it a good idea not to smoke if you have an immunodeficiency?

Smoking is harmful even if you are healthy, but if you have an immunodeficiency it’s even more important not to do it. When you smoke, the brush-like fibres in your lungs are inactivated or destroyed. This allows thick mucus to accumulate in the lungs and reduces your defence against infection.  

Cigarette smoking also increases the risk of lung cancer and disease in other parts of the body, especially heart attacks and strokes. There is lots of help available these days to help you stop smoking – speak to your doctor, nurse or local pharmacist. 

I have lung problems, should I still exercise?

Yes. Exercise and keeping fit allow the body to use oxygen more efficiently and can help your lungs work better. Only exercise until you feel out of breath and don’t do too much. Discuss this with your doctor. 

Find out more about exercises you could try.  

What should I do if I think I have a chest infection?

Contact your doctor as soon as possible. Remember to tell him/her you have a PID. Some patients have emergency antibiotics to have at home and, if you have these, it might be appropriate to start taking the course. 

If I have a lung infection, what medicines will I be given?

In theory, it is best to take an antibiotic that your doctors know will work against the specific infection that you have. In practice, this isn’t so easy because the sputum (mucus) test results take a few days to come back and it is not usually wise to delay starting treatment. This means that your doctors will usually recommend treatment with an antibiotic that is known to work against a range of lung infections, or be guided by the results of previous sputum tests. People with established lung disease (bronchiectasis) may sometimes need higher doses of antibiotics, or longer courses, to stop the infection. 

Your doctor may give you a broad range antibiotic but sometimes he/she will want to identify the microbe causing your infection, if it doesn’t respond to treatment. This will involve giving a sputum test. 

What is a sputum test?

It’s a test used to detect or identify bacteria or fungi that may be causing chest problems and involves giving a sample of sputum (mucus that you might cough up from the airways). Some people don’t produce sputum. If this is the case, and it is really important to know which infection is in the lung, an examination with a telescope, called a bronchoscopy, might be used to collect samples from deep inside the lung. The sputum sample is placed in a sterile container and sent to the laboratory to see if it grows a certain type of bacteria or fungi. From these cultures, doctors are able to identify the microbes involved and give better-targeted drugs to clear the infection. 

How do doctors test how well I’m breathing?

Doctors use lung function tests to assess how healthy your lungs are. 

What are lung function tests?

Lung function tests, which can also be called pulmonary (pronounced “pull-moan-ary”) function tests, measure how well your lungs work. These tests are used to look for the cause of breathing problems, such as shortness of breath. 

What do lung function tests measure?

They measure: 

  • How much air you can take into your lungs. 
  • How much air you can blow out of your lungs and how fast you can do it. This amount is compared with that of other people your age, height and sex. This allows your doctor to see whether your lungs are working normally. 
  • How well your lungs deliver oxygen to your blood. 
  • The strength of your breathing muscles. 

Why are lung function tests used?

Doctors use these tests to diagnose and monitor your lung health and to see if there is any damage caused by scarring of the organ’s tissue. These tests may also be used to check how well treatments are working. 

What lung function tests are used?

The breathing tests most often used are: 

  • Spirometry (pronounced “spi-rom-eh-tre”). This test measures how much air you can breathe out. It also measures how fast you can blow air out. This is the simplest and most important test. It requires you to blow out as hard as you can to get the best results. 
  • Lung volume measurement. This test, taken along with a spirometry, measures how much air remains in your lungs after you breathe out fully. 
  • Lung diffusion capacity. This test measures how well oxygen passes from your lungs to your bloodstream. 

Some tests measure the oxygen level in your blood and are called blood oxygen tests. There are two tests:  

  • Pulse oximetry, which measures your blood oxygen level using a special light. The test is painless and only if the results indicate a problem would your doctor normally suggest a blood oxygen test. 
  • Blood oxygen test, when the doctor inserts a needle into an artery, usually in your wrist, and takes a sample of blood. The oxygen level of the blood sample is measured. This test is more accurate than pulse oximetry. Some units are now able to do this test from the ear lobe too. 

Do lung function tests hurt?

Lung function tests are usually painless and rarely cause side effects. The technician will ask you to blow as hard as you can to get the best results, and the tests are repeated a few times, which can make people feel tired. You may feel some discomfort during an arterial blood oxygen test – when the needle is inserted into the artery.

These tests may not show what’s causing breathing problems. This has to be assessed separately and may involve giving a sample of sputum.

What is the role of a physiotherapist in lung health?

Physiotherapists have a key role in maintaining respiratory health. Perhaps the most important role is teaching people techniques to clear sputum effectively, if this is a problem. Being very breathless can be frightening, and physiotherapists are trained to teach people specific breathing techniques that help with these symptoms.

They also run exercise and education classes called “pulmonary rehabilitation” that can be effective for people with more severely affected lungs.

What medicines are available to decrease lung infections and inflammation?

Antibiotics can be used to treat and prevent infections. The commonest antibiotics used to treat chest infections would include penicillin drugs such as amoxicillin and co-amoxiclav, or different types called macrolides (e.g. clarithromycin) or tetracyclines (such as doxycycline). 

Sometimes antibiotics are used in a different way – not to treat but to prevent infections. This might be suggested to you if you are having frequent or severe chest infections. The commonest antibiotic used in this way is called azithromycin, and it is often taken just three times each week. Using an antibiotic in this way – called a “prophylactic” – is a decision that has to be discussed carefully. Some patients will be put on nebulized antibiotics for the same reasons. Using an antibiotic long term has the risk of side effects or of the bugs becoming resistant to the antibiotic. These risks have to be balanced against the benefits of having fewer infections.

Can inhalers help open my airways?

Inhalers are a good way to get respiratory drugs to where they are needed most – the lungs.  Most inhalers contain an anti-inflammatory and/or a drug called a “bronchodilator” that can open up the airways. 

If breathing tests show that your airways are narrowed, doctors may recommend that you try an inhaler to see if it improves the test results, reduces your symptoms and increases your exercise capacity.

These FAQs were kindly reviewed by Dr John Hurst, Senior Lecturer and Honorary Consultant, Centre for Respiratory Medicine, University College London Medical School and Royal Free London NHS Foundation Trust, London, December 2021.