Children’s Respiratory Physiology 

Your letter may also ask you to stop taking certain inhalers and medications before you have this test. Please check any instructions on your letter or text message.   

If your child is unwell on the day of your appointment, please contact us on 0116 258 5691 to discuss if it is appropriate for us to continue with the appointment.

If you are attending for an exercise test, please make sure your child wears appropriate clothes and shoes. We also recommend bringing a drink.

The test measures how much air you can blow out and how fast you can do it.

How the test works

It is performed with the help of a physiologist. A physiologist will be there to measure your height and weight. You will take a big breath in and blow out as fast as you can into a tube. It is a little bit like how you would blow candles out. The physiologist will keep doing this until we are happy with your results.

Sometimes, the physiologist will give you some blue inhaler (Salbutamol) and ask you to do the test again. This will help us see if the blue inhaler helps your breathing.

The test usually takes 15 to 20 minutes, or longer if medication is required.

Please follow instructions in your appointment letter (some inhalers may need to be stopped beforehand). If you are unwell on the day, call us to check if you should attend.

How long will it take?  

The test may only take around 15 to 20 minutes. If we need to give you a blue inhaler, it may take 30 to 40 minutes.   

Please note: you may be told you are having spirometry at your clinic appointment. If this is the case, you will have your breathing test and see the doctor to discuss your results.   

This test looks at different parts of your breathing.

This is a breathing test made up of three parts: 

• The fast-breathing test (spirometry) will tell us how much air you can blow out and how fast you can blow. 
• The breath holding test (diffusion capacity) will tell us how well your lungs are working.  
• The box test (body plethysmography) will tell us how big your lungs are.

How long will it take?  

The whole test may take between 45 minutes to 1 hour. Each little test will only last a couple of seconds and we will give you plenty of rest in between.   

This test looks at the muscles involved in breathing.

A muscle function test is a breathing test made up of different parts:

• The fast-breathing test (spirometry) will tell us how much air you can blow out and how fast you can blow.
• The cough test (cough peak flow) will tell us how strong you can cough.
• The blow and suck test (MIP/MEP) will tell us how strong your breathing muscles are.
• The sniff test (SNIP) will also tell us how strong your breathing muscles are.

What do I have to do?  

A physiologist will be there to measure your height and weight. Don’t worry if you can’t stand, they will measure how long your arms are instead. They will also help you with all the tests and tell you what to do for each one.  

When you do the fast-breathing test you will take a big breath in and blow out as fast as you can into a tube. It is a little bit like how you would blow candles out.  

You will also take a big breath in and cough into the tube for the cough test.   

For the blow and suck test you will be asked to blow/suck as hard as you can into the tube. We will make it hard for you to blow/suck so that you can show us how strong you are.   

When we do the sniff test, you will have a little tube up your nose, and we will ask you to sniff as hard as you can.

How long will it take?  

The whole test may take between 45 minutes to 1 hour. Each little test will only last a couple of seconds and we will give you plenty of rest in between.  

This is a test to see if exercise changes your lung function. Sometimes when you have asthma, you will find it harder to breathe after you exercise. You will do a fast-blowing test before and after exercise.

What do I have to do?  

A physiologist will be there to measure your height and weight. They will also help you with the test.  

You will start with a fast blowing test. You will take a big breath in and blow out as fast as you can into a tube. It is a little bit like how you would blow candles out.  

We will then put a little sticker on your finger so we can measure your heart rate.   

When you are ready, we will ask you to run on a treadmill for 6 minutes. If your breathing becomes too difficult, you can tell us, and we will stop the run.   

Once the run is finished, we will do the fast blowing test a few times. This will help us see if the run has changed your breathing.   

We will then give you some blue inhaler (Salbutamol) and ask you to do the test again. This will help us see if the blue inhaler helps your breathing.  

How long will it take?  

The test can take up to 90 minutes.   

This test will help us see if you have asthma. You will be asked to do fast blowing test before and after some medicine.

What do I have to do?  

A physiologist will be there to measure your height and weight. They will also help you with the test.  

You will start with a fast-blowing test. You will take a big breath in and blow out as fast as you can into a tube. It is a little bit like how you would blow candles out.  

You will then use a different tube to breathe in some medication (provocholine). This may make you cough. When we start this part of the test, your parents or carer will have to watch through a window.   

We will then do the fast-blowing test. If your lung function has not changed, you will have some more medication.   

If your lung function changes, we will give you some blue inhaler (salbutamol) to make it better.   

How long will it take?  

The test can take around 60 minutes.   

This is an exercise test to see what your body does when you exercise. It can help us find out why you are breathless when you exercise or if you struggle to be as active as your friends.

What do I have to do?  

A physiologist will be there to measure your height and weight. They will also help you with the test.  

You will start with a fast blowing test. You will take a big breath in and blow out as fast as you can into a tube. It is a little bit like how you would blow candles out.  

We will then get you ready for the exercise test. You will wear different pieces of equipment to help us monitor you when you exercise. This will include:  

• A mask over your nose and mouth so we can monitor your breathing. 
• A clip on your ear so we can check your oxygen levels. 
• Stickers on your chest (ECG) so we can monitor your heart.
• Something wrapped around your arm so we can measure your blood pressure.  

You will pedal on an exercise bike for around 12-15 minutes. It will be easy to pedal at first but as the test goes on it will become harder. We will ask you to keep pedaling until you can’t do it anymore.  

After the test, you will wear all the equipment for a few minutes whilst we make sure your body recovers from the exercise.   

How long will it take?  

The test may take around 60 minutes. You may be doing other tests on the same day (such as a pulmonary function test).   

Please make sure your child wears appropriate clothes and shoes to cycle on an exercise bike. We also recommend bringing a drink.

This is a simple sleep study to monitor your child’s oxygen levels and heart rate whilst they are asleep.

What do I have to do?  

When you attend your appointment, a physiologist will demonstrate the equipment. They will answer any questions you may have.   

At home, you will be expected to plug the monitor into mains power and switch it on. Your child will be required to wear a plaster-like sticker on their finger, toe or foot for the study. In the morning, you can remove the sticker and switch the machine off ready to return to the department.   

You must keep a record of when your child is awake and asleep.   

You will be expected to return equipment the next working day (before lunch time).

This sleep study combines an oximetry study and a capnography study. It allows us to monitor your child’s oxygen levels, heart rate and carbon dioxide levels whilst they are asleep.

What do I have to do?

When you attend your appointment, a physiologist will demonstrate the equipment. They will answer any questions you may have.

One monitor will measure your child’s oxygen levels and heart rate. You will be required to plug the machine into the mains power and switch it on. Your child will be required to wear a plaster-like sticker on their finger, toe or foot for the study.

The other monitor will measure your child’s carbon dioxide levels. You will be required to plug the machine into the mains power and switch it on. Once the machine is ready, your child must wear a small sensor (a 5p coin size) on their chest or ear. You will have to change its location every 4 hours.

You must keep a record of when your child is awake and asleep.

In the morning you can remove all the equipment from your child and turn the machines off.

You will be expected to return equipment the next working day (before lunch time).

This study monitors your child’s breathing, oxygen levels and heart rate whilst they are asleep.  Depending on the age or needs of your child, we can perform this at home or may ask you to stay the night in hospital. If you have received a letter asking you to stay overnight for this test, please see Hospital Based Cardiorespiratory Sleep Study (CRSS) information below.   

What do I have to do?   

When you attend your appointment, a physiologist will demonstrate the equipment. They will answer any questions you may have.  

The equipment is battery powered and will be programmed to turn itself on/off. Your physiologist will prepare all the equipment ready for bedtime but you will need to place it on your child at home.  

Your child will be required to wear:  

• A small nasal cannula(tube that sits under the nose) – this will help us look at the air coming in and out of your child’s airways and if they snore.   
• Soft stretchy belts around their chest and stomach – this will help us look at their breathing rate and effort  
• A sticker around their finger or toe – this monitors your child’s heart rate and oxygen levels.   

In the morning, you will remove all the equipment and place it in a bag ready to return to the department.

You will be required to keep a record of when your child is awake and asleep.   

You will be expected to return equipment the next working day (before lunchtime). A physiologist will demonstrate the equipment and answer any questions you may have during your appointment.   

This study monitors your child’s breathing, oxygen levels and heart rate whilst they are asleep.  Depending on the age or needs of your child we can perform this at home or may ask you to stay the night in hospital.  If you have received a letter asking you to collect equipment to use at home please see Home Based Cardiorespiratory Sleep Study (CRSS) information above.

Members of our team or our respiratory nursing team perform the hospital based sleep study set ups. You will be asked to come to the Children’s Day Care Unit (Level 4, Windsor building, LRI) where you will stay for the evening. Once the equipment has been set-up, the nurse will handover to healthcare assistants will stay on the unit overnight.   

There will be no medical review when you attend. You will be required to leave the unit by 7am the following morning.   

What do we need to bring for the sleep study?  

A parent or carer will be required to stay overnight with your child for the sleep study. The parent/carer is responsible for the child’s care throughout the stay. Only one parent/carer is allowed to stay with the child.   

You may wish to bring:  

• Food/snacks – We will provide a small sandwich, yogurt, fruit and a drink for your child. But if you wish to bring your own food, you will have access to a kitchen with a microwave. You will not be allowed to leave the unit to get food once the set-up has begun. You will be offered breakfast before you leave, however, you must be left the unit by 7am.   
• A thin vest and spare socks – Some children like to play with the equipment once it is set up. Therefore, we recommend that you bring a thin vest to go under any nightwear. This allows us to set up the equipment on top of the vest and hide it away with the nightwear. Socks for bedtime also help us to keep the sticker on the toe.   
• Any special toys, blankets or pillows your child usually sleeps with. You will be able to choose for your child to have a cot or a bed for the night. You will have a parent bed in the room with your child.   
• Toys/electronics – only some of our sleep study rooms have a television. There is a large play area in the unit with a selection of toys.  So you may wish to bring your own entertainment for your stay. But please be mindful that there are other families staying on the unit at the same time as you.   
• CPAP/Ventilator/Oxygen – please contact us prior to your appointment if your child uses any machine overnight.   

What will happen once we arrive?  

A member of our respiratory nursing team will show you to your room for the night and let you get settled. They will ask that your child gets ready in their nightwear ready to set up the equipment.   

Once you are settled, the nurse will come and set up your child’s sleep study. This will include:   

• A small nasal cannula(tube that sits under the nose) – this will help us look at the air coming in and out of your child’s airways and if they snore.   
• Soft stretchy belts around their chest and stomach – this will help us look at their breathing rate and effort  
• A sticker around their finger or toe – this monitors your child’s heart rate and oxygen levels.  

They will also ask you if you would be happy for them to set up a camera to monitor your child.    

The nurse will answer any questions you may have about the study or your stay.   

What do I have to do?  

The nurse will explain all the equipment as they perform the set-up. The night staff are not trained in using the equipment, so we ask that you replace any equipment that is removed. If equipment has been removed and we do not get sufficient data for analysis, we may have to repeat the study.  They will also ask you to record when your child is asleep and awake.   

Once the study is set up, you are free to eat, play and relax. At 7pm, the night staff will take over and help you get ready for the night. They will be on the unit all night if you need anything.  

Once your child is awake for the day, you can take off all the equipment and leave it for staff to collect.  

 You will be offered a small breakfast. You can then leave the unit. Please note – you must be left before 7am. If you wish to leave before this time, you may do so.   

What is a Flight Assessment? 

When you go on an airplane, oxygen levels are lower than on the ground. In some people, this can mean the oxygen in their body drops to a level that is not safe. We therefore perform a test where we drop the oxygen you are breathing in to a level similar to that on an airplane and monitor you.  

What do I have to do? 

You will have to wear a plaster like sticker on your toe or your finger. You will then sit in the inflight test box. If you are scared, your parent or carer may be able sit in the test box with you.  You can take toys or a computer tablet with you too.  

We will lower the oxygen levels like it is when you are on an airplane. You will then stay in the box for 20 minutes whilst we check your body’s oxygen levels. If they drop too low, we may give you some oxygen through a little tube at the end of your nose.  

Is there anything I need to know before my appointment? 

It gets warm inside the testing box, so wear light and thin clothing! If your child uses a CPAP or ventilator or has overnight oxygen, please confirm with your physiologist if they require it for the study.