Respiratory Tests

Respiratory & Sleep Service offer full complex respiratory function testing (RFT) to Specialist Respiratory Physicians, Specialist Physicians from a range of other medical disciplines, Surgeons and General Practitioners.
To ensure accurate results, it is essential to follow all pre-test patient instructions for all tests.
The tests provided are as follows:


Pre and Post Bronchodilator

Spirometry is the most basic test of airway function. It can be used to determine the presence and severity of any obstructive and restrictive ventilatory defects. In the presence of an obstructive ventilatory defect the degree of response to bronchodilator can also be assessed. This is a useful test for monitoring a number of ventilatory disorders including asthma and chronic obstructive pulmonary disease.


Fractional exhaled Nitric Oxide

An exhaled nitric oxide test can help with the diagnosis and treatment of asthma. Also known as the fractional exhaled nitric oxide (FeNO) test, this test measures the level of nitric oxide gas in an exhaled sample of your breath. This sample is collected by having you breathe slowly and steadily into a mouthpiece that's attached to a machine that performs the measurement.

Additional pre-test patient instructions required


Gas Transfer Factor Single Breath

Known as DLCO, TLCO or diffusing capacity this test measures the uptake of trace carbon monoxide as a proxy for oxygen. It provides useful information about lung parenchyma and pulmonary vasculature in a non specific way. As a measure of gas uptake it is useful in assessing diseases as diverse as bronchiectasis and interstitial lung disease. It is particularly useful in assessing changes due to various forms of chemotherapy treatments known to affect the lungs.

Lung Volumes

Plethysmography 'Body Box'

Plethysmography is used to measure the volume of air in the lungs when the respiratory muscles are relaxed, which is referred to as functional residual capacity (FRC). Plethysmography is also used to measure the total capacity of the lungs (TLC). As a measurement of lung volumes, it is useful in the diagnosis of restrictive lung diseases such as pulmonary fibrosis and asbestosis. It is also particularly useful in evaluating gas trapping occurring in the lungs as a result of various obstructive lung conditions.

Bronchial Provocation


This is a sensitive test for identifying airway hyperreactivity. This means it has a high positive predictive power and a low negative predictive power for airway hyper reactivity. As such, a negative bronchial provocation can be a useful test for excluding airway hyper reactivity as a differential diagnosis.

CO Testing

Exhaled Carbon Monoxide Test

Most people with high levels of carbon monoxide are smokers. The exhaled carbon monoxide test is a useful tool to monitor smoking and help people to quit. The test can also show if you're being exposed to dangerous levels of carbon monoxide in second-hand smoke, even if you don't smoke yourself.

Respiratory Pressures

A respiratory pressure meter measures the maximum inspiratory and expiratory pressures that a patient can generate at either the mouth (MIP and MEP) or inspiratory pressure a patient can generate through their nose via a sniff manoeuvre (SNIP). These measurements require patient cooperation and are known as volitional tests of respiratory muscle strength.


Airwave Oscillometry (FOT) assesses the patient's pulmonary function during quiet, tidal breathing with no patient effort required, by superimposing a gentle, multi-frequency oscillation on top of the patient's natural breathing

Oximetry Screening

Pulse oximetry (also called pulse ox) is a simple and painless test that measures the level oxygen is in the blood.