Calculating Health
DigitalHuman simulator prepares for blastoff
With a few keystrokes in DigitalHuman, a computer program developed at the University of Mississippi Medical Center, researchers can create an overweight and diabetic virtual patient, run him up a flight of stairs, give him a heart attack, then analyze thousands of moment-by-moment metrics to better understand the human body.
Scientists at NASA using a version of the program are predicting health problems astronauts could encounter three years into a mission to Mars.
Dr. Tom Coleman, professor emeritus of physiology and biophysics, estimates between 50-100 medical schools around the world use DigitalHuman for training.
Training is one thing. But Coleman and two colleagues, Dr. Robert Hester and Dr. Richard Summers, are throwing open the doors even wider. They plan to release DigitalHuman in open-source code next month.
Coleman, also senior biomedical systems analyst in the Department of Emergency Medicine, began building digital models of the human circulatory system in the late 1960s with the late Dr. Arthur Guyton. They used off-hours computing power rented on room-sized monstrosities belonging to a hospital billing department and an area bank.
“Think about when I first started. The digital computer was just being invented,” Coleman said. “The integrative model, now called DigitalHuman, was started in 1985. Before that, Dr. Guyton, myself and others were building smaller models – since the available technology at that time couldn’t solve big models.”
The 1985 model offered about 150 variable traits, including respiration rate and arterial pressure. That’s now expanded to more than 5,000 variables, including liver-glucose uptake rates and hypothalamus function.
Hester, professor of physiology and biophysics, helped guide DigitalHuman and secured research funding. That’s come from agencies including NASA, the National Institutes of Health and the National Science Foundation.
“Over the years, Tom’s done an amazing job developing it and Richard on testing it. We realize we’ll never be done adding to it, but we’re ready to put out an open-source version,” Hester said.
The new version will let other scientists build on the program, adding their own specialties with more variables. It all but guarantees DigitalHuman will expand as quickly as scientific knowledge itself.
“It’ll still be a UMMC product, but we want to open it up to the scientific community,” said Summers, professor of emergency medicine.
To handle submissions from other scientists, they plan to use a system akin to Wikipedia’s.
“As the scientific community becomes more involved, scientists could put forward modeled relationships and submit them to a library as potential add-ons to the larger program,” Summers said. “We would, of course, verify the work before adding it. But you’d have groups of scientists submitting smaller models specific to their specialties.”
At the same time, Coleman will keep adding more depth and specificity. Users recently asked for a female model so they could figure in different hormones, menstrual cycles and other variables. Coleman has completed simulation of the menstural cycle and plans other additions.
“But just going from male to female gave us the notion of traits: age, gender, adiposity, muscularity and so on. This is getting pretty close to predicting individual-specific outcomes,” he said.
With more depth, researchers globally will get more use from the program.
At NASA’s Glenn Research Center in Cleveland, Ohio, scientists are expanding a version called DigitalAstronaut.
Why? Because nobody’s got much data about what happens to humans biologically during long space flights. Or when we live on Mars, which has three-eighths gravity. Since it’s a bit clunky to send a research facility into space, running DigitalAstronaut simulations in Ohio makes more sense.
“We’re adding depth IN AREAS where more detailed simulations are needed to reflect the possible outcomes of prolonged space flight,” said Dr. DeVon Griffin, DigitalAstronaut project manager.
At the moment, he’s working on detailed modules for cardio, bone turnover and renal-stone formation.
“If you go to Mars, you’re going to spend six months in flight, a year-and-a-half on the ground and six months back. We have zero data on what happens in three-eighths G, but this program could simulate it,” said Dr. Jerry Myers, technical lead on DigitalAstronaut at Glenn.
One way the different gravity would affect humans is cell absorption rate of water, Coleman said. “And you’d need to know how much water to send on a mission.”
Summers, who coordinates with NASA, said DigitalAstronaut solved some problems that confounded the agency for 20 years. Though other scientists have developed computer-simulation programs, Griffin said none are as integrated and comprehensive.
“The Mississippi Code is the most advanced, the most cutting-edge,” he said.
The U.S. Environmental Protection Agency is using DigitalHuman to model chemical exposures, including carbon monoxide. Previously, the EPA tracked a virtual inhalation of toluene, an industrial chemical and solvent believed to affect the nervous system.
Scientists at Stanford University programmed DigitalHuman’s respiratory component into a device that could predict optimal settings for a ventilator at a patient’s bedside. Researchers at the University of Scranton have used it to model high-altitude exercise and found its outcomes very close to human results, Hester said.
The opportunities for future uses for DigitalHuman will expand with technology and scientific knowledge.
“A hospital in Washington, D.C., wants to use it to train clinicians on treating burn victims,” Hester said. “We’ve been contacted by a lot of companiesabout looking into it.”
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Jack Mazurak 2009-04-10 00:00:00 18886 |
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Copyright © 2003 The University of Mississippi Medical Center. All Rights Reserved.
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