Tests and Services

Actigraphy (Actiwatch) - for Sleep studies

Actigraphy is a non-invasive method of monitoring human rest/activity cycles. Actimetry sensors which detect movement can be worn on the wrist like a watch.

Airway resistance

Airway resistance is the resistance of the respiratory tract to airflow when breathing in and out. Airway resistance is measured using a plethysmograph (body plethysmograph or body box). A body plethysmograph is a see through plastic cabinet and for the test the patient sits inside and breathes into a mouthpiece with their palms resting gently on their cheeks. The patient is asked to pant for a short period. Diseases affecting the respiratory tract can affect the level of airway resistance.

BIPAP (bilevel positive airway pressure)

BIPAP is a type of non-invasive ventilation (involving a machine with a mask that fits over the mouth and/or nose) that uses two different levels of air flow. The airflow is strongest when breathing in, to help the patient take in air. Airflow pressure is lower when breathing out, but remains positive. This continual positive pressure helps to keep the airways open, and improve oxygen uptake.

Bronchial Challenge test

A bronchial challenge test assesses the reactivity of the airways and can be used to assist the diagnosis of asthma. The patient breathes in a drug, either as a mist or a powder. The drug can cause a temporary narrowing of the airways in some people.

Capillary Blood

During breathing oxygen is taken into the lungs and carbon dioxide is breathed out. Both these gases are carried in the blood. In some conditions these levels can become altered and if the levels go above or below a certain limit it can be very dangerous. A simple and easy way to test these gases is by taking a blood sample from the earlobe. Some special cream will be applied to the earlobe. This will have the effect of warming the ear and encouraging good blood flow. Once the ear has warmed sufficiently the cream will be wiped off and a small lancet will be used to make a small scratch on the earlobe. The blood will be collected into a thin glass tube and taken for immediate testing. 

Capillary Blood Sample

During breathing, you take in oxygen and breathe out carbon dioxide. Both these gases are carried in the blood. In some conditions these levels can become altered and if the levels go above or below certain limits it can be very dangerous. A simple and easy way to test these gases is by taking a blood sample from the earlobe. Some special cream will be applied to the earlobe. This will have the effect of warming the ear and encouraging good blood flow. Once the ear has warmed sufficiently the cream will be wiped off and a small lancet will be used to make a small scratch on the earlobe. The blood will be collected into a thin glass tube and taken for immediate testing. 

Cardio-Pulmonary Exercise Test (CPET)

Cardio Pulmonary Exercise Testing (CPET) measures how the lungs, heart and muscles react to exercise. CPET can be useful in investigating breathlessness and it also helps estimate risk for patients undergoing surgery. The CPET test is done on an exercise bike or treadmill. The patient breathes through a mask while cycling. The amount of oxygen breathed in and the carbon dioxide breathed out are measured, as well as breathing rate and rhythm and blood pressure.

CPAP (continuous positive airway pressure)

CPAP uses a constant positive air pressure to keep airways open. CPAP typically is used for people who have breathing problems when they are asleep Obstructive Sleep Apnoea (OSA). CPAP treatment involves a machine with a mask that fits over the mouth and/or nose to deliver the airflow.

DLCO or TLCO (Diffusing capacity of the lung for carbon monoxide - see also Transfer Factor)

DLCO or TLCO (Diffusing capacity or Transfer factor of the lung for carbon monoxide) measures how well oxygen passes from the lungs into the blood. During this test the patient is seated and the nose is sealed with a noseclip. The patient breathes normally into a mouthpiece, followed by a relaxed blow all the way out until the lungs are empty. They then breathe in as possible. When the lungs are full, the patient holds their breath for approximately 9 seconds and then blows out fully.

Endurance Shuttle Walk test

The Endurance Shuttle Walk Test is a constant-paced field walking test to assess endurance capacity in patients The patient is asked to walk at a set speed between two cones spaced 10 metres apart. They will wear a finger probe to monitor the oxygen levels and pulse.

Exhaled Nitric Oxide

During inflammation, higher-than-normal levels of nitric oxide (NO) are released cells in the airways. The concentration of NO in exhaled breath, or fractional exhaled nitric oxide (FeNO), can help identify airway inflammation, and so support a diagnosis of asthma

FEV1 (Forced Expiratory Volume in one second)

FEV1  is the volume of air that can forcibly be blown out in one second after taking in as deep a breath as possible and blowing out as fast and as much as possible  - See Spirometry

Gas transfer


Helium dilution

Helium dilution testing is a way to measure lung volumes (see also plethysmography). In the helium dilution test the patient breathes a gas mixture containing helium for 2 or more minutes. When the level of helium is stable the patient is instructed to breathe in than exhale fully in a relaxed manner.

Home Oxygen service

The Oxygen Service assesses patients to see if they need long-term oxygen therapy (LTOT). In some patients with chronic lung disease one of the main problems can be the low level of oxygen in the blood, which can put the body under stress, particularly the heart and brain. Giving oxygen for at least 15 hours a day reduces this strain by increasing the amount of oxygen that these organs receive. To measure the oxygen level in the blood a sample of blood is taken from the earlobe and analysed. If the oxygen levels are satisfactory the test may stop there. If the oxygen levels are below a certain level the patient is put on oxygen and the blood test repeated after 20 minutes. The Service provides help, education and support for patients on LTOT and reviews patients to ensure the best treatment possible is given.

Hypoxic challenge (flight assessment)

As a result of the lower oxygen levels at altitude, most passengers will experience a decrease in oxygen saturation – the amount of oxygen circulating in the body. This is normally tolerated well in healthy individuals. People with cardiac and respiratory problems however, may experience complications. The hypoxic challenge test is to assess whether the patient will require additional oxygen during flight. The test takes 20 minutes. The patient breathes in a mixture of air and nitrogen through a mask which results in reducing the oxygen level to simulate being in an aircraft.  The oxygen level is monitored using an oximeter and blood may be taken from the earlobe to provide more detailed information about the blood oxygen levels. The patient may be given some additional oxygen via a mask if their oxygen levels fall during the test.

Incremental Shuttle Walk test

The purpose of this test is as a measure of fitness. The patient is asked to walk between two cones spaced 10 metres apart (without stopping for a rest) by following a series of time signals (beeps). At the start the pace is very slow and gradually gets faster until the patient cannot keep up with the pace. Heart rate and oxygen levels are monitored using a finger probe.

Induced Sputum

Inducing sputum by breathing in a mist of saline solution is a simple, safe procedure to collect respiratory secre­tions from lung airways for diagnosis of various respiratory diseases. It is used to assess airway inflammation in asthma and chronic obstructive pulmonary disease (COPD) and can also be used to study respiratory infections and TB.  The sputum induction test is a painless procedure. It involves breathing in different concentrations of saline (mild salty water) through a nebuliser and then performing cough-like movements to produce a sample of sputum. The test will take approximately 30 minutes to perform.

Limited/ Multi-channel Polysomnography (Sleep studies)

Limited/Multi-channel polysomnography is a test performed at home to give information about breathing whilst the patient is asleep. The patient collects the equipment from the department and is shown how to set attach the probes.  The machine will measure: breathing movement, by attaching a small sensor under the nose; snoring pattern, and chest wall movement using small sensors, which are held in place by Velcro belts.

Lung volumes (Plethysmography and helium dilution)

A measurement of the total lung volume and the distribution of air in the lungs can help with the diagnosis and evaluation of lung conditions. This test looks at the overall size of the lungs and the volume of air that remains after exhaling maximally. Regardless of how hard you try, there is always a bit of air left in the lungs, the volume of this can give valuable information on how well the lungs are working. There are several methods for making this measurement (see plethysmography and helium dilution).


A nebuliser is a machine that produces an aerosol spray which can be breathed in to deliver drugs to the lung. It can be used to deliver bronchodilators or antibiotics.

Nitric Oxide

Nitric oxide (NO) is a gas molecule produced by human cells and the NO levels may change in patients with conditions that involve inflammation of the airways, such as asthma. Exhaled nitric oxide (eNO) can be measured in the breath, using special equipment. The patient is asked to take a deep breath in as fully as possible and blow out at a steady pace for about 10 seconds.

Non-invasive ventilation

Non-invasive ventilation (NIV) refers to the provision of support for breathing through the patient's upper airway using a mask or similar device. This technique is distinguished from those which use tracheostomy and are therefore considered invasive. Pressurised airflow is blown into the mask while the patient breathes; Airflow can be continuous (this system is known as CPAP (continuous positive airway pressure) or given at two different pressures (BIPAP, bi-level positive airway pressure): inspiratory positive airway pressure (IPAP) to help the patient breathe in, and a lower expiratory positive airway pressure (EPAP) when breathing out.

Obstructive sleep apnoea (OSA)

Obstructive sleep apnoea (OSA) is a condition where the walls of the throat relax and narrow during sleep, interrupting normal breathing. When breathing is interrupted, lack of oxygen triggers your brain to pull you out of deep sleep – either to a lighter sleep or to wakefulness – this allows the airway to reopen and breathing to return to normal. This can also result in loud snoring. After falling back into deep sleep, further interruption to the patients breathing can occur. This might happen around once every one or two minutes throughout the night in severe cases. These repeated sleep interruptions can make the patient feel very tired during the day. They usually have no memory of the interrupted breathing, so may be unaware of the problem unless a partner, friend or family member notices the symptoms while they sleep. The test for this condition is overnight oximetry. This is done in the patient’s home and shows whether the blood oxygen falls when the breathing is interrupted. A further more detailed study may be performed which looks not only at the oxygen level but also at effort to breathe and the airflow to the lungs (see Limited polysomnography)  If a diagnosis of sleep apnoea patients may be offered treatment with CPAP (Continuous Positive Airway Pressure).

OSLER (Oxford Sleep Resistance Test)

This is a test of sleepiness. The patient sits in a darkened room and is instructed to activate a button when a small light flashes.  The test may last up to 40 minutes. 


An oximeter is a probe that clips on your fingertip or earlobe to measure how much oxygen is in the blood.  Sometimes it is attached to a monitor that you wear on your wrist, like a watch. The oximeter doesn't take blood. It shines a light though the fingertip or earlobe, and measures how red your blood is. A pulse oximeter is useful in any setting where a patient's oxygenation is unstable and can help determine if there is a need for supplemental oxygen.


The test measures the total volume of the lungs and the distribution of air inside them. The patient sits in a special see through plastic cabinet and breathes into a mouthpiece with their palms resting gently on their cheeks. The patient will be instructed to gently pant in and out against a closed shutter. At the end of the test they are asked to breathe in deeply and then to breathe out as much as possible.

Pulse oximetry (SpO2)

See Oximetry

Respiratory Muscle strength MIPS/MEP

Respiratory muscle strength can be assessed by measuring the maximal inspiratory pressure (MIP also known as PImax, and the maximal expiratory pressure (MEP or PEmax). The MIP reflects the strength of the diaphragm and other inspiratory muscles, while the MEP reflects the strength of the abdominal muscles and other expiratory muscles. Measurement of the MIP and MEP can be made with a small hand held monitor or connected to a computer. To measure MIP the patient is asked to breathe out completely and then breathe in hard for a couple of seconds.  To measure MEP the patient first breathes in as much as possible and then with a sharp blast blow the air out for at least a couple of seconds.

Reversibility Spirometry

This involves doing a spirometry test, then breathing in an aerosol medicine called a 'bronchodilator'. Bronchodilators are designed to expand the bronchial airways that carry air in and out of the lungs. After breathing in the medicine, the patient waits for about 20 minutes. The spirometry test is then repeated to see if the results have changed. These tests help to diagnose asthma or COPD, and to decide which treatments suit the patient best.

Six minute walk test

This test requires the patient to walk as far possible at their normal walking pace up and down a corridor for 6 minutes. The patient and can stop and rest as many times as required.

Sleep studies

See Limited Polysomnography

Spirometry (see also FEV1)

Spirometry measures how much and how fast and what volume a person can blow out. The device that is used to make the measurements is called a spirometer. The patient is asked to breathe in as much as possible and then to blow out as hard and as fast as possible.  The Vital Capacity (how much air is blown out, the FEV1  (Forced Expiratory Volume in one second) which is how much air can expelled from your lungs in the first second of breathing out and Peak Expiratory Flow rate which is how much is forced out in the first 10 milliseconds, can all be measured. This test can help tell whether breathing is obstructed by narrowing of the airways (as found in asthma or COPD).

Transfer factor 


Further information for patients about these types of testscan be found at the website of the Association for Respiratory Technology and Physiology (click here)