Learning about illness - using breath

Supplementary content information

Professor Gus Hancock and colleagues discuss the many things we can learn about the body's health through the breath: and new technologies that can make that process easier.

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Professor Gus Hancock – Professor of Chemistry, University of Oxford [GH]

Hippocrates told his students that you should always, particularly when diagnostic methods were not very advanced, smell the presence of disease on breath. It really took off quantitatively with Nobel laureate Linus Pauling doing measurements of the substances which emerge from breath. Since then around a thousand compounds have been found in the breath of various human beings and a typical human will have four hundred different materials coming out on their breath, often at levels which are exceptionally low. Physiologists had a problem; they wanted to learn directly how the human body uses oxygen, what the rates of consumption are and how these changed with particular conditions.

Dr Luca Ciaffoni – Research Assistant, University of Oxford

As a volunteer breaths in and out through the device, you will see a changing composition of the oxygen, carbon dioxide and water concentration within the airways on a real time basis and the core of this device is that it will combine this simultaneous measurement and produce an estimate of the oxygen uptake and CO2 production on a breath by breath basis. This is something quite challenging to achieve, which is not currently done during surgery, so the idea is that this could bring a huge amount of information to clinicians and help particularly in cases where you need to provide, for example, 100 per cent of oxygen to resuscitate a patient who has had a cardiac arrest.


Thinking about whether we can make some commercial activity out of this is how the spin-out company formed and eventually became Oxford Medical Diagnostics with the major target being the detection of the molecule acetone. Acetone is a molecule which has long been associated with diabetes and particularly so when a diabetic is essentially out of control, when the insulin therapy is not working or the person doesn’t know that they have got diabetes, which happens in young children, and the body accumulates a chemical known as ketones. These chemicals break down and produce acetone on the breath.

Tom Blaikie – Technical Officer, Oxford Medical Diagnostics

What we do is we get the user to hold their breath for three seconds and then just bring it out fully into a breath bag. We then take that bag and attach it to the device; the device has got a pump in it which draws the breath through into the sampling chamber. We then measure the amount of light that is absorbed by the breath sample. This is measured by a detector and then this outputs a reading of the amount of acetone in that person’s breath in parts per million. We are also hoping that we can use this breath acetone measurement to hopefully one day provide a way of non-invasively measuring blood glucose, particularly for young children as measuring your blood glucose involves taking a finger prick test and this can be quite uncomfortable and distressing.


The thing that’s happened with the small impact programme that we have been funded for now is that we have set up exercise tests and routines; we’ve got some data although we haven’t finished this yet. Will it be of any use? I don’t know. Will the impact with our breath analyser for anaesthesia be of any use? I can say for that it looks as if we are going to have some real use for it within the medical profession. We have champions who are willing to put this into operating theatres and we hope into intensive care units.