A new monitoring system may help clinicians to hear intestinal vibrations better - a move that could enable faster diagnosis and recovery, its creator tells Claire O'Connell
They may not be the stuff of polite dinner conversation, but bowel sounds or "tummy rumbles" are important indicators of gut health. Caused by the movement of food and air through the intestines, these indelicate gurgles can provide clues about how the intestines are working.
Doctors currently place a stethoscope on the patient's tummy to listen for bowel activity. But this is a subjective approach, and one that may miss out on quieter signals, according to electromechanical engineer Dr John Hession.
He has developed a new, more sensitive way, of picking up intestinal noises. First, several small sensor pads are put on the patient's tummy to detect vibrations coming from inside the gut. The sensors are wired back to a computer, which then removes background noises like the heart pounding and lungs wheezing, making the bowel sounds easier to distinguish.
The system could help clinicians to monitor patients as they recover from surgery and may be of use in diagnosing certain bowel conditions, says Dr Hession, who developed the device for his PhD with Dr Brendan McCormack at the Institute of Technology Sligo.
For example, after a major operation, the intestines can go into shock, and doctors often wait until bowel sounds re-occur before letting a patient start eating food again.
But it may be several days before a clinician can hear sounds coming from the gut, explains Dr Hession. "There's a huge implication for hospital costs here and the amount of time people spend in hospital."
Dr Hession tested his acoustic monitoring system at Sligo General Hospital to see how it fared against the stethoscope. He found that his vibration sensors on the surface of the tummy could pick up a patient's bowel sounds long before a clinician could hear them using the more conventional approach.
"This means that perhaps feeding could have commenced at a much earlier stage," he says. "There was rumbling going on there, but it was below the threshold of hearing."
To find out more about the characteristics of gut noises, Dr Hession built a replica model of the working bowel.
He pumped various mixtures of food, water and air through the plastic intestine while monitoring sounds with the sensors.
"I was able to measure the size of the bubble passing through it and the acoustic signal it was producing," he explains, adding that this was the first time anyone had ever shown what a bowel sound is.
He also worked out that the skin and fat over the tummy reflect most of the energy from gut vibrations back into the body, which explains why we generally don't hear digestive noises from the outside.
But despite the faintness of the noise at the surface, Dr Hession says his system can still detect early bowel sounds after surgery.
He describes how, in practice, the machine could monitor a patient's bowel activity and flick on a light when they are ready for food again. "So it wouldn't be necessary for a clinician to come around and check every day," he says. "It would free up clinician time."
In addition to checking patients after operations, Dr Hession hopes the device could also help doctors to diagnose certain events in the bowel, such as an obstruction.
"When you get a blockage in the bowel, the sound increases pitch around that area. It is a much more aggressive sound," he says.
He believes his system could help pinpoint characteristic sounds from the intestine, making it easier for doctors to detect features such as kinks, polyps or bleeding in the gut. "So you could tell, to a fairly significant location, where a blockage occurs."
The technology could help detect bowel problems alongside other tools such as ultrasound and computed tomography (CT) scans, according to Mr Martin Caldwell, a consultant surgeon at Sligo General Hospital, who was involved in the project.
He speculates that the new system could also be of use in researching conditions such as irritable bowel syndrome.
But he notes the device is still at the bench stage. "The next step is to take it into the clinical setting," he says.
And Dr Hession is currently planning to develop the acoustic monitoring system for clinical use.
He says the system won't replace the more traditional methods of stethoscopes and ultrasound, but he believes it will help refine our understanding of what is going on in the intestine.