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Cardiac Services
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Respiratory Outpatient Diagnostic Testing

We provide a wide range of respiratory tests for investigating a range of symptoms including shortness of breath, coughing, wheezing, exercise intolerance and more. These tests can be used to diagnose and monitor respiratory conditions such as: Asthma, COPD, Pulmonary fibrosis, Sarcoidosis, Cough of unknown cause, Exercise induced Asthma, Shortness of breath on exercise, Respiratory muscle weakness or Assessment for fitness to fly.



Spirometry is a basic test done to assess how quickly you can move air into and out of your lungs.  It gives your doctor an indicator of whether your airways are obstructed or the movement of your lungs restricted.  For patients who already have a respiratory diagnosis, spirometry is used to monitor the progression of a condition or response to medication.

Full lung function 

Full lung function testing involves three different breathing tests to gain an overall view of how your lungs are working, these tests are all non-invasive and involve you breathing though a tube.  

A full lung function test includes:

  • Spirometry (see above) to assess the movement of air into and out of the lungs
  • Gas transfer test to assess how effectively the oxygen you breathe into your lungs transfers across into your blood system for delivery to where it is needed
  • Body plethysmography to look at how large your lungs are (total lung capacity) and how much air is left in your lungs when ‘emptied’ (residual volume) 


A reversibility assessment is always done in conjunction with either spirometry or full lung function.  After the spirometry or full lung function is complete the Physiologist will ask you to take a dose of Salbutamol (Ventolin) from an inhaler. After waiting 20 minutes (allowing the medication to take effect) the spirometry will be repeated to see if the inhaler has improved the results.  This test is often done in patients with, or who are suspected of, having Asthma.  If you are currently taking any inhalers it is important to discuss with your doctor to see if these should be stopped prior to the test taking place.


A mannitol test is known as a bronchial challenge test. The test involves performing a baseline spirometry (see above); we will then ‘challenge’ your airways by asking you to breathe in increasing doses of a dry powder called Mannitol and we will repeat the spirometry after each dose to assess for any changes. If your airways are normal then they will not react to the mannitol and the results of the spirometry will remain stable throughout.  If however you have hyper-sensitive airways (such as in Asthma) then the mannitol will affect the airways and we will see a change in the spirometry results as the test progresses.  

Cardiopulmonary exercise test 

A cardiopulmonary exercise test (CPET/CPX) is a maximal exercise test where we simultaneously monitor your heart and your lungs whilst you exercise on a bicycle.  Throughout the test we monitor your ECG (heart rhythm), heart rate, blood pressure, oxygen saturations (SpO2), your oxygen uptake and carbon dioxide output through breathing.  We ask that you push yourself during this test so that we can achieve the highest values you are capable of.  All the information together will provide your consultant with a large amount of data so that they can identify what factors are affecting your exercise performance.  

This test is also known as a VO2 max test.  The VO2 max is the amount of oxygen you are breathing in per minute at your maximum point of exercise; this is often used as a marker as to how fit/athletic you are.  

A CPET is indicated in a wide range of situations:

  • To assess the severity of a known exercise limitation; particularly assessing over time with repeat testing
  • To determine the cause of exercise limitation
  • To determine the fitness level/suitability to perform an upcoming exercise related task 
  • To investigate physiological correlates to patients symptoms under exercise

Capillary blood gases (CBG) 

We take a small sample of blood from your earlobe to assess the levels of different gases and biological substances within your blood. We look at levels of oxygen, carbon dioxide, lactate, bicarbonate and the pH of the blood.  The test gives information on the current oxygenation status and a picture of long-term respiratory and metabolic status.

Fit to Fly assessment (hypoxic challenge)

A hypoxic challenge test will determine if you require supplemental oxygen during a flight. In a commercial aircraft the cabin is pressurised to the equivalent of 8,000ft where the oxygen levels in the air are 15% and lower than at sea level (21%).  In a normal healthy individual this will result in the blood oxygen levels dropping a small amount but this would not cause any symptoms or adverse effects.  However, altitude exposure in patients with pre-existing lung disease and those with low oxygen levels at sea level may have more significant adverse effects from the lower oxygen levels in the aircraft.  During the test we will monitor your blood oxygen levels, heart rate and symptoms whilst you breathe 15% oxygen; this is all done non-invasively via a clip on your finger.  If your doctor requires we may do this test in conjunction with capillary blood gases (see above).  If your oxygen levels in your blood remain stable the test is finished after 15 minutes; however if your oxygen levels fall we will give you supplemental oxygen to breathe until your blood oxygen levels remain stable; in this instance your doctor is likely to advise you can fly but only with supplemental oxygen.


This test comprises of several breathing manoeuvres to look at the strength of the respiratory muscles; these tests would be indicated in cases of suspected respiratory muscle weakness or paralysis.  We record both the maximum inspiratory pressures (MIPs) and the maximal expiratory pressures (MEPs).

Supine VC

A baseline spirometry (see above) is done in the sitting position or standing position; the patient is then asked to lie down on their back and the spirometry repeated to determine if there is any difference between the values when sitting and when on their back.  This test is done in cases of suspected diaphragm weakness or paralysis.

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Our symptom control team are here to help you manage symptoms, especially if you have heart failure or lung disease

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Our dieticians play a crucial role in the care of all cardiac and thoracic patients               

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Contact Us

London Bridge Hospital


Tel: 03331 308 177

General Enquires

Tel: 020 7407 3100

Tax: 020 7234 2019


27, Tooley Street
London SE1 2PR

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