Acid test

The technology used to cool central processing units (CPUs) in computers could be used to quickly diagnose patients with acid-related disorders in the oesophagus.

Researchers at The Royal London Hospital are adapting the computer-cooling technique through a two-year government-sponsored project.

The aim will be to create a miniature device, similar to a thermometer, that would be inserted into the patients’ oesophagus. The device would then be heated up and left there for 30 to 40 minutes.

Drugs that suppress acid secretion from the stomach and reduce symptoms in patients with acid reflux in the gullet are available but a number of patients fail to respond to this treatment.

Professor Qasim Aziz, professor of neurogastroenterology at The Royal London Hospital, said this could be due to the fact that repeated acid reflux has caused increased sensitivity of the nerves in the lining of the gullet so that these nerves are activated by small amounts of acid which would be considered normal.

‘Currently it is difficult to determine if the nerves in the gullet have become sensitised or not,’ added Prof Aziz. ‘We know that nerves that respond to acid also respond to changes in temperature. However, thus far it has been difficult to devise methods for stimulating these temperature-sensitive nerves in the gullet.’

William Mach, spokesman for Barts and The London NHS Trust, which runs the Royal London Hospital, said the device will address this as it will be used to detect temperature sensitivity.

When patients feel a heat sensation, he added, they will push a button and the temperature of the device will be recorded. The device can also be used to measure sensitivity to cold.

Mach explained that the core technology behind the device is based on the Peltier effect. The technique is used for transferring heat in computer CPUs to cool them down.

The effect was discovered by French physicist Jean-Charles Peltier in 1834 after joining copper and bismuth wires together and connecting them to a battery. After switching the battery on, he found the temperature rose at the junction where the current passes from copper to bismuth, and the temperature dropped at the junction where the current passes from bismuth to copper.

Mach said that this is the first time the technology will be applied for medical testing.

It is expected that doctors will be able to use the information gathered from the temperature testing to determine a patient’s level of sensitivity and develop a plan for therapy.

The method would replace current acid perfusion tests, a technique designed to determine acid-related disorders by replicating symptoms of reflux. These tests involve inserting a tube into one side of a patient’s nose and down into their oesophagus. A mild hydrochloric acid is then sent through the tube followed by a saline solution.

The developers of the new device claim that these tube tests do not always result in a definitive diagnosis or specific explanation of a patient’s symptoms. It is hoped that the new sensory testing techniques will provide a better underlying of the mechanisms of oesophageal pain.

Mach added that the main engineering challenges for the researchers will be figuring a way to heat up the device rapidly inside a patient’s body.

‘The body’s core temperature is 37°C,’ he said. ‘They aim to heat this device up to 50°C and at the same time not create any problems with the patient’s blood flow.’

The other challenge, Mach added, will be to make sure that the patient’s tissue cools uniformly back down to the core body temperature.

‘In other words, there needs to be a way to remove heat from the system,’ he said.

The researchers have already developed a 7mm diameter prototype, but the team seeks to make ones that could be more easily inserted into a patient’s oesophagus. The group hopes to have a tested thermal device ready to be trialled within a large-scale clinical study in two years time.

The Royal London Hospital, Whitechapel, has earned a £113,000 two-year grant to work on the project. This will be managed by the National Institute for Health Research.

Siobhan Wagner