Researchers have built a machine that will take your breath away. In a few weeks they expect to be given clearance to use breath sensors to diagnose illnesses.
The device, which will check if heart transplant recipients are suffering organ rejection, is intended to be the forerunner of sensors that can analyse exhalations and pinpoint those with breast or lung cancer, pre-eclampsia (a blood disorder that can affect pregnant women) and angina. Some scientists believe it may even be possible one day to create hand-held devices, like the 'tricorders' used by Dr McCoy in Star Trek, to give rapid diagnoses of many common illnesses.
'Different illnesses produce different chemical fingerprints in the body, and we have discovered how to detect these in a person's breath,' said Professor Michael Phillips of New York Medical College. 'It is an ideal, non-invasive way to find out what is going on inside a patient.'
Doctors have known for years that some illnesses have detectable effect on a patient's breath. Those with typhoid fever are said to smell like freshly baked brown bread, while diabetics have the scent of old apples. It is even claimed by some practitioners of alternative medicine that dogs can detect cancer in a person's breath.
Scientists started to build complex analysers - gas chromatography machines and mass spectrometers - putting the study of breath on to a proper scientific basis. Early studies showed that we have traces of several hundred different volatile chemicals in our breath.
The discovery raised the prospect of pinpointing combinations of chemicals unique to a particular illness. 'It was an exciting idea, but several problems had to be overcome, not so much in detecting chemicals but in collecting the breaths of patients we wanted to study,' said Phillips.
'Each of us has two types of breath: dead-space breath, which comes from the upper air passages of the body, and alveolar breath, which is found far down in our lungs. It is the latter we want to study, for its contents reflect what is going on deep inside our bodies. Getting it out is the tricky bit.'
After lengthy trials, Phillips and colleagues, who have set up a company called Menssana Research to market their system, designed a device that uses a powerful pump to suck a patient's breath through a stainless steel tube filled with carbon which absorbs the volatile chemicals in their breath. 'We do, literally, take people's breath away,' Phillips said.
The carbon, impregnated with volatiles, is removed and sent to a central laboratory where it is analysed to reveal its chemical constituents. From these analyses the breath patterns of sick and healthy patients can be built up and compared.
Phillips and his team have uncovered a definitive pattern, based on the prevalence of a couple of dozen chemicals, that is produced by the body when it begins to reject a newly transplanted heart.
Most operations are successful these days, but rejection can still occur. The sooner this is pinpointed, the more effective is the doctor's response. 'You can do a biopsy - but that involves sticking a catheter into a patient's neck and pushing down through to their hearts to get a tissue sample. Breath sensors will save you having to do that.'
Phillips has received preliminary approval from the US Food and Drug Administration for the breath test device and has been told that full approval is likely next month. 'We will have our first devices in use within months,' he said. 'They won't replace biopsies completely, but they should reduce the need for them quite considerably.'
Heart transplant devices are likely to be followed up in the near future with lung and breast cancer devices, says Phillips. He explains: 'There are about a hundred key chemicals in the breath that tell us what state of health a person is in. We need to find the ones that are the most important for individual diseases, particularly illnesses, such as lung cancer, which are difficult to detect because they lie deep inside our bodies. Breath sensors offer us a painless, non-intrusive method for doing that.'
