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Factoring for humans

Anesthesiologists have led the way at designing medical devices to reduce human error—but other specialties are following

By Andrew Skelly

Originally appeared in The Medical Post

The airline and nuclear industries have long understood the importance of designing their systems to account for human nature. In comparison, another "safety-critical" field—medicine—has for the most part been slow to catch on.

But the often problematic interaction between people and health-care technology is getting more attention in the wake of the U.S. Institute of Medicine's 1999 report "To Err is Human," which estimated medical errors kill between 44,000 and 98,000 Americans each year.

Dr. Kim Vicente (PhD), professor and director of the Cognitive Engineering Laboratory at the University of Toronto and a visiting professor at the Massachusetts Institute of Technology, is one of the leading researchers in human factors engineering—the design of technology to suit human needs, rather than expecting people to adapt to the technology.

"It can be anything from a toothbrush that's designed to fit the shape of your hand . . . or it could be the design of an operating room to make it easier for a team of surgeons and nurses and anesthesiologists to work together and do surgery more safely," he says.

"You can apply this process to basically almost any piece of equipment, or even any work process, in a hospital. The possibilities are virtually endless."

Those possibilities include patient monitoring equipment, ventilators, drug labels, working hours, ambulance dispatching and even hospital beds.

Dr. Vicente, along with engineer Laura Lin and anesthesiologist Dr. John Doyle, recently gained attention for what they claim is the first experiment to evaluate the impact of a human factors redesign of a commercially available medical device on experienced users.

The device in question is a common infusion pump for patient-controlled analgesia—the Abbott LifeCare 4100 PCA Plus II.

There have been several reports of overdose deaths blamed on misprogramming of drug concentration, and Dr. Vicente and colleagues suspect that's only the tip of the iceberg.

But before they even knew about those reports, they had picked the device as a test case for their human factors approach.

They based their redesign of the pump's programming interface on such apparently common-sense principles as: make the functions of the controls clear and obvious; provide users with prompt, salient feedback after each action; make the displayed messages easy to understand; and minimize the load on the user's memory.

The new design, for example, displays an overview of the programming steps and highlights the current step, so users can see where they are in the programming sequence. It also reduces the number of programming steps by prompting the user with multiple options—for choice of units, for example—instead of one option at a time.

In the study, the original and redesigned interfaces were simulated on a personal computer. Twelve recovery room nurses from Toronto General Hospital, who averaged more than five years of clinical experience with the LifeCare 4100, participated.

The nurses were asked to program each interface six times. They made fewer than half as many errors with the new version (13 versus 29). Moreover, they made no drug concentration errors, but committed eight such errors with the old interface—including three that were not corrected.

Dr. Vicente says the difference between the two designs could be even bigger in a busy, distraction-filled hospital.

Other researchers have shown that computer-based interfaces for a patient-monitoring system in cardiac anesthesia and an infusion device for terbutaline therapy of preterm labour suffer from similarly poor designs that could benefit from human factors re-engineering.

The specialty that was probably the first to apply such principles in redesigning its equipment and procedures with patient safety in mind was anesthesiology.

"We're in a high-tech service, and we're a service where technology interfaces with human performance and patient care probably more so than any other medical profession," says Dr. Beverley Orser, an anesthesiologist at Sunnybrook and Women's College Health Sciences Centre and a professor at the University of Toronto who has worked with Dr. Vicente.

Because the operating room is a dynamic, fast-paced environment, it's critical equipment and procedures be designed to minimize the chance of mistakes, and minimize the harm if mistakes do occur, says Dr. Orser.

To this end, Canadian anesthesiologists were pioneers in developing clinical practice guidelines, and their U.S. counterparts were the first to establish a patient safety foundation.

The Canadian Anesthesiologists' Society has also recently established a patient safety committee.

"That's the sort of mentality we need to build into all of our delivery systems," Dr. Orser says.

In a British Medical Journal article, Dr. David Gaba, a professor of anesthesiology at Stanford University, pointed out that increasingly more complex technology, and concern over soaring malpractice premiums in the 1970s and 1980s, made patient safety a priority for anesthesiologists.

Dr. Gaba and Dr. Jeff Cooper (PhD), a biomedical engineer at Massachusetts General Hospital, applied lessons learned from aviation to the study of how to prevent errors in anesthesiology.

Simple strategies such as standardized controls and gas connectors that prevent a hose or cylinder from being installed at the wrong site likely contributed—along with new technology such as pulse oximetry—to a more than 20-fold improvement in the anesthesia mortality rate.

But proponents say the importance of human factors engineering will only grow as the health-care system becomes more technologically complex.

"We need to step back and say how can we change our environment and our systems around us to maximize patient safety," says Dr. Orser.

"And that's where I think as physicians we really have to play a role.

"We have to be aware there's a problem and not assume that it's OK and that it can't be changed. We're at the sharp end and it's our duty to be proactive in this."