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The professional nurses in the video appear to have taken lessons at the Charlie Chaplin school of slapstick comedy. Asked to change the medication and the dosage on a machine, the nurses fumble.

Pushing a button on the infusion pump that should start the change procedure doesn't seem to work. Pressing other buttons doesn't do anything either.

Suddenly the nurses are called away by an emergency alarm. When they return to the (simulated) patient, they can't remember where they are in the process.

"Oh, shoot," says one and begins to administer what would have been the wrong dosage of the new drug.

"It's an order-of-magnitude difference that is extremely dangerous to the patient," Anjum Chagpar, manager of the Healthcare Human Factors Group at Toronto's University Health Network, says as she watches the nurse making the potentially fatal dosage error.

Fortunately there is a happy ending to the story - and one that demonstrates a new trend in how medical equipment is designed, tested and evaluated by health care researchers working with manufacturers.

Ms. Chagpar's group, housed in a new $6-million facility, began operating less than three years ago and has quickly become what is believed to be the world's largest hospital-based human-factors research centre.

(Human factors analysis, also called ergonomics or usability testing, is the term describing the linkage between a technology and its ease of operation.)

The UHN is an umbrella institution comprised of three hospitals -Toronto General, Toronto Western and Princess Margaret. Its Human Factors Group made the video of the nurses when the UHN was considering buying new versions of pain-pump machines. A copy of the video showing the resulting confusion was sent to the machines' manufacturers, including Smiths Medical in Minnesota, a division of London, England-based Smiths Group PLC.

"They saw the video and quite honestly they were mortified," recalls Joseph Cafazzo, the UHN's director of medical device informatics and health-care human factors team.

Smiths' mortification led to an extensive two-year collaboration between the company and the UHN centre to develop a user-friendly "smart" pump-infusion system.

Working with a hospital-based centre was important to Smiths because the UHN group's 15 research staff and graduate students have access to 3,000 nurses and 1,000 doctors - a pool of technology testers that an individual manufacturer just can't match. Smiths could also take advantage of the centre's not-for-profit business model, by which companies are charged for materials and staff at a fixed hourly rate.

It's estimated there are between 5,000 and 10,000 North American companies making medical devices - and only a handful have the capacity to do extensive in-house human factors testing.

The industry, which generates an estimated $150-billion (U.S.) in yearly worldwide revenue, including more than $25-billion in North America, has been under increasing pressure to ensure its devices and machines don't lead to medical error - and resulting lawsuits and public relations woes.

Michael Wiklund, a medical human-factors expert in Concord, Mass., cites a series of products whose design flaws triggered legal action in the United States, such as anesthesia and drug-infusion machines, ventilators and sleep apnea devices.

Manufacturers are under increasing government pressure to include usability studies to ensure their products are safe. U.S. Food and Drug Administration regulations have led to de facto world standards that require manufacturers to "demonstrate adherence to good design practices."

But medical devices - built to be durable and long-lived - aren't subject to the competitive pressures that force consumer products such as cellphones and computers to become more user-friendly.

"It's not uncommon for these devices to costs millions of dollars and be in use for a decade or two," Mr. Wiklund notes. In other words, if errors are engineered in, they stay in.

The UHN centre's collaboration with Smiths was its first complete start-to-finish human-factors engineering effort.

In all, 10 design iterations were made for the new infusion machine (which is awaiting FDA approval before going to market). The project began with Smiths shipping simple paper-and-pencil drawings for the UHN staff to work on. That was followed by computer-based interactions, and then tests on prototype devices.

The end result includes improvements which, upon reflection, seem obvious. For example, one reason the nurses became confused in using the old infusion pump was because the button needed to halt delivery of a drug was not labelled "Stop." Worse, to get that button to work the nurse had to keep pressing it rather than just push it once. Nor was there anything to prevent a confused user from giving the wrong dosage. The new machine has none of those problems.

"What was surprising to us about the process was ongoing improvements in each iteration," says Tom Ulseth, Smiths' senior worldwide marketing manager who oversaw the company's efforts.

"It would get better, and then when you thought you had it, it would get better on top of that better."

Neither Smiths nor the UHN would reveal the cost of the two-year joint effort. But Mr. Wiklund has estimated it costs upward of $300,000 to make a new medical device truly user-friendly.

The Human Factors Group's work with manufacturers is expanding. It recently completed a contract with the U.S. military to test the ease of handling of a portable intensive care unit designed to be attached to a stretcher. To replicate real-life conditions, researchers worked in a mockup of a helicopter interior.

The group is also working with an Ontario manufacturer whose devices are aimed at making emergency wards more interactive. One would help nurses use a computer program to triage incoming patients; another would let patients use a computerized system to evaluate their condition while waiting to be seen. Other research looks at how bedside computer terminals can serve patients, nurses and doctors.

Demand for the group's evaluation work is exploding, Ms. Chagpar says. "We are fielding requisitions from ministries of health, from cancer agencies, and we are working with hospitals both within and without the province. Not to mention continuing to work with medical device manufacturers."