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Other Specialist Tests

Before your appointment

In addition there may be a number of other specialist tests the doctor may ask the lung function department to perform.

Lying and sitting vital capacity

We will ask you to breathe in and out through a mouthpiece as deeply as possible in the sitting position and then repeat the test while you are lying down. This will add approximately 10 minutes to the tests.

Respiratory Muscle Strength

Respiratory muscles are those which are used for breathing, such as the diaphragm. There are three different tests involved in assessing respiratory muscle strength.

The first is very simple and requires you to breathe normally in and out through the mouthpiece. The mouthpiece will then block randomly for a very short duration, approximately 0.1 seconds. This will be performed at least ten times while you breathe normally.

The second test assesses your inspiratory muscle strength. We will ask you to breathe out as far as you can and then try to breathe in against a blocked tube as hard as you can for at least 2 seconds. This will then be repeated at least 3 times.

The last test assesses your expiratory muscle strength. We will ask you to breathe in as far as you can and then try to blow out against a blocked tube as hard as you can for at least 2 seconds. This will then be repeated at least 3 times.

This test normally takes between 10-20 minutes to complete.

6-minute walk

We will ask you to walk up and down our corridor for 6 minutes. You will be able to walk at your own pace; you can stop and have a rest as many times as you feel you need to and you can use any walking aids you use everyday. We will ask you every minute how breathless you are feeling and we will be monitoring your oxygen levels throughout by attaching a light-emitting probe on your finger. This will add approximately 10 minutes to the tests.

Skin allergy test

Small drops of different allergens in solution (e.g. house dust mite, animal hair) will be placed on your forearm. The skin where the droplets are placed will be scratched with a very small lancet. These are designed to only go through the very first layer of your skin and will not draw any blood. After a few minutes there may be an itchy sensation on the skin and after fifteen minutes you may have a reaction that looks a little like a small insect bite. These will be measured to determine whether you have provided a positive reaction. We will give you some cream at the end of the test to make any reaction go away. This will add approximately 15 minutes to the tests.

Histamine provocation

We will ask you to perform a number of quick blasts into our machine before and after inhaling different doses of a substance called histamine. This is a chemical that is found naturally in the human body which causes some people to become a little wheezy. There are a maximum of 12 doses. If there is a positive reaction to the test then the speed you are able to blow the air out will reduce a little, but we will stop the test before this gets too much. This will add a minimum of 1 hour to the tests.

Exercise-induced asthma

We will ask you to perform a number of quick blasts into our machine before and after exercising on a bicycle. The exercise is designed to increase your heart rate quite high. Please wear suitable clothing for performing exercise. Some people find it a little more difficult to blast the air out a few minutes after the exercise, but we will stop the test before this gets too much. This will add at least 1 hour to the tests.

Sleep study

We will ask you to take home a small wrist watch-type device which you will wear overnight. This also has a light-emitting probe to be placed on your finger and will measure the levels of oxygen in your blood while you are asleep. This will need to be brought back to the department the next day for analysis.

Fitness to Fly

We will ask you to breathe for 20 minutes through a mouthpiece which is attached to a cylinder containing slightly less oxygen than you breathe normally. This is the same oxygen content as that on an aeroplane. Blood will be taken from your wrist before and at the end of the test. The test will determine whether you need to take supplemental oxygen on your flight or not. This will add up to 1 hour to the tests.