From Nasa to knickers

June 30, 2000

Space technology is being used to solve the problem of incontinence. Geoff Watts reports.

A medical system that can transplant a failing heart or rejoin a severed limb still cannot offer a wholly satisfactory remedy for what seems to be a far simpler problem: a leaking bladder. Supported by the charity Action Research, the latest organisation to take on the challenge of incontinence is the Brunel Institute for Bioengineering. With its reputation for innovative thinking on topics as far removed as space travel and disability, incontinence sufferers have reason to be hopeful.

The institute was founded by Heinz Wolff, whose parallel interests in space engineering and "tools for living" are continuing under the present director, Ian Sutherland. "In space, where things are different, we're used to lateral thinking," he says. "Some of the spin-offs we get from space technology can be applied to problems such as incontinence."

Around the world at least 200 million people are incontinent, but the past two decades have seen little technological progress. Absorbent pads - bulky and uncomfortable - are the most common remedy. But for people with limited mobility, getting them on and off can be an impossible task.

Women suffer more from incontinence than men and, anatomy being what it is, present a greater challenge to the water engineers. Female urinals are cumbersome at the best of times; even the lithe of wrist may spill their contents during retrieval from the action zone. For the continent but disabled - women with multiple sclerosis, for example - they can be impossible to manage. New thinking, of a kind, has certainly been tried. But even when the dates on the patent applications are recent, the diagrams accompanying some of them look Victorian.

"We've got some awful ones from the 1990s," says Felicity Jowitt, an industrial designer in the Brunel team. "One is a pair of long waterproof knickers. They go down to your knees and are meant to form a seal round them. The knickers are fitted with two large-bore pipes running up the inside of your legs to your crotch. You're meant to connect one of these pipes to a warm water supply, and the other to a wet-and-dry vacuum cleaner."

The Brunel researchers' ideas are less brutal - though no less ingenious. In their device, escaping urine is removed through a tube connected via a valve to a storage chamber in which a partial vacuum is maintained by an electric pump. Any leakage of urine activates an electronic heat sensor, which opens the valve and allows the fluid to be sucked into the chamber.

This description raises two obvious questions. First, why a heat sensor? Answer: because checking for moisture rather than temperature would result in suction being applied for as long as the sensor remained not wet, but merely damp. Second: why a stored vacuum? Why not allow the sensor to activate the pump directly?

"A pump can't get going quickly enough," according to biologist Eleanor Tinnion. "The first rush of urine flows at 25ml per second. If you have just one second's delay you've got 25ml of urine sloshing around."

A stored vacuum can take effect the instant the valve opens. For collecting the fluid when it first emerges the researchers are using either a very slim urinal - a curving, elongated collection cup that slides between the legs - or a specially designed pad. With the former, the suction system would eliminate the spillage problems that make urinals difficult even for the continent but immobile.

The alternative to the urinal is a pad some 20cm long and 3-4cm wide with a tube running out of one end. It is impermeable except for a central strip on the side lying against the opening of the urethra. Any urine entering it would activate the sensor and promptly be sucked out. What is sucked out is a mixture of air and liquid. A device in the lid of the storage container allows only the liquid to pass. Filters of this kind were first developed for handling liquids at zero gravity: the space technology connection.

The team is working on two prototypes: one fitted to a wheelchair, the other portable enough to be worn inside a small waist bag. Among the problems that have already been overcome is a slurping noise heard whenever suction was applied. Changing the materials inside the collection pad solved that one. Pumps, too, can be noisy.

But Jowitt is optimistic. "When you're asking for 10,000 pumps you can say you want the smallest, quietest one that can be made. At the moment we just have to take the best we can find."

The system works well in healthy volunteers and, in collaboration with the Continence Product Evaluation Network at the Whittington Hospital, north London, Tinnion hopes soon to begin trials on patients. "The first tests will be with the urinal, and probably with women who either use urinals already or would be suitable for them. They know when they want to go to the toilet, but they can't get there in time. Then we'll be testing the pads on people who don't know when they need to go."

Tinnion and Jowitt reckon their device could eventually be made for about Pounds 200, plus the cost of certain disposable items. Set against that would be savings on pads and, more important, the labour involved in dealing with people who cannot manage for themselves. Sufferers would judge it on a non-monetary scale: peace of mind.

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