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Tests And Investigations

If your doctor thinks that you may have a chest condition you may need the following tests / investigations:

• Sputum specimen
• Chest x–ray
• Heart tests
• Lung function (or breathing) tests
• Blood tests
• CT scan
• Bronchoscopy

Sputum specimen

The mucus in your airways is also referred to as sputum.

You may be asked for a sputum specimen which will be sent to a laboratory to see if there are any micro organisms (germs) in your lungs. This will tell your doctor if you have an infection and exactly which antibiotic treatment is required.

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Chest x–ray

You may have a chest x–ray. This is usually done to rule out any other conditions or if your symptoms have got worse.

Heart tests

The doctor may suggest that you have some heart tests to check how your heart is working, e.g. to see if your heart is working excessively hard to get the blood through the lungs.

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Lung function (or breathing) tests

The following tests help to assess any damage to your lungs:

• Peak flow test: measures how hard you can blow air out of your lungs. You have to blow into a 'peak flow meter' which has a marker on the side which moves as you breathe out, giving a 'peak flow reading'. Usually the best of 3 readings is used. The peak flow reading measures the amount of air you blow out (in litres per minute). If your airways are narrowed you will not be able to blow very quickly and your peak flow reading will be low. This can be done at your doctor's surgery or you can be given a peak flow meter to do this test at home.
• Spirometry: assesses how well you actually breathe. You breathe into the mouthpiece of a spirometer to measure the volume of air that you can inhale and exhale over a period of time. This can be done at your doctor's surgery or at the respiratory clinic at your local hospital. Spirometry is the most important test in diagnosing COPD.
• Pulmonary function test (PFTs): more complex breathing tests that measure the volume of a full breath in and also the volume of air that you exhale. This has to be done at your local hospital.

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Blood tests

Routine blood tests include:

• Full blood count (FBC): measures the levels of red blood cells, white blood cells and platelets. It also measures the haemoglobin (oxygen–carrying component of red blood cells).
• Urea and Electrolytes (U & Es): urea levels help to monitor how the kidneys are working. Electrolytes (e.g. sodium, potassium) and minerals (e.g. calcium) help to stabilise the heart rhythm.
• Glucose: measures the level of sugar in the blood.
• Liver and thyroid function.

Hospital doctors also sometimes want to check your arterial blood level. (Routine blood tests are taken from a vein.) Arterial blood samples are usually taken from an artery in the inside of your wrist and can be uncomfortable.

Another method of checking your blood oxygen levels is to take a capillary blood sample from your earlobe. This is less painful than an arterial blood sample.

Arterial and capillary blood samples give an accurate level of the oxygen and carbon dioxide in your blood. This can help to see if you need oxygen therapy.

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CT scan

A CT scan gives a more detailed picture of your lung tissue. It is helpful in diagnosing certain chest diseases such as emphysema or bronchiectasis and can also help to rule out other disorders.

• HRCT (High resolution computed tomography): an HRCT scan is needed to diagnose bronchiectasis. It uses special CT scanning techniques and is the most accurate non–invasive method of assessing lung tissue.

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Bronchoscopy

• A flexible bronchoscopy allows your doctor to look at the inside of your lungs and take biopsies and specimens. It is performed in hospital, usually as a day case. Local anaesthetic spray is used to numb your nose and throat. Some mild sedation can also be given if required. A small flexible tube is passed up your nose and down into your lungs. It is a relatively quick and painless investigation.
• A rigid bronchoscopy is always done under general anaesthetic.

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