Space-age medicine for earthly practices

Washington -- If Earthbound physicians think that they have problems getting patients in for routine care, pity the plight of National Aeronautics and Space Administration doctors. Their patients are often out of this world.

As the space agency dreams about future manned flights to Mars that will need at least a one-year round-trip flight, plus time for exploration, concerns about astronauts' health are getting a heightened level of attention.

For instance, space's near weightlessness weakens bones and muscles. Astronauts face intense bombardment with heavy ion radiation, which kills red blood cells. And disruption in circadian rhythms can deprive them of adequate rest.

Research to address these and other conditions is emerging from the Houston-based National Space Biomedical Research Institute, founded by NASA in 1997. The institute is guided by a consortium of 12 primarily medical colleges that coordinates the work of 250 investigators from 75 institutions to "meet real, pressing, high-priority needs," said NSBRI Director Jeffrey Sutton, MD, PhD.

Although space travel vastly intensifies medical problems, people on Earth face many of the same difficulties. Osteoporosis afflicts millions, and shift workers and many others grapple with sleep disorders. Thus, the fruits of NSBRI's efforts could find their way into physicians' practices on Earth before long.

In the quest to address bone loss caused by extended periods of microgravity, Yi-Xian Qin, PhD, associate professor of biomedical engineering at Stony Brook University in New York, has developed an ultrasound system that goes beyond assessing bone density to look at bone quality.

"A lot of patients might have good density scores but still suffer fractures within the spine or hip," Dr. Qin said. A fracture on Mars would constitute a disaster, but a break on Earth carries a huge risk as well.

The current gold standard in assessing bone health, the dual energy x-ray absorptiometry, or DXA, assesses bone density but not bone quality. Bone loss in space as well as on land often results from the quality of the trabeculae, or honeycomb interior of bone. The ultrasound technology would detect this value and offer a new level of insight.

Additional technology that doesn't poke or jab astronauts as they hurtle through the Milky Way is also in the development phase. Babs R. Soller, PhD, associate professor of anesthesiology, surgery and biomedical engineering at the University of Massachusetts Medical School, is heading a research project that is refining near infrared spectroscopic techniques to provide needle-free blood and tissue measurements.

The longer wavelengths of near infrared light generally can pass through skin and to some extent bone, letting physicians and others obtain chemical information about tissues and blood noninvasively, she said.

Dr. Soller believes the astronauts might be able to use it to measure tissue pH to determine how hard a muscle is working, a major question in space. Here on Earth, it could be used to measure muscle atrophy for people on bed rest. Other potential applications include treating patients in shock due to excessive bleeding or heart attack, patients with internal bleeding and children who won't sit still for a needle.

Additional devices being developed include one that will run tests on a very small amount of blood -- one-tenth of a drop -- or other body fluid. Although noninvasive technology is an NSBRI goal, a tiny blood sample would be required for the portable body fluid analysis system envisioned by researchers at the California Institute of Technology, said principal investigator Yu-Chong Tai, PhD, professor of electrical engineering and bioengineering.

"Current technology does not allow NASA to check astronauts' blood counts in space," he said. But blood counts hold an important place in assessing astronauts' health because they are continually bombarded by red-blood-cell-depleting radiation -- the equivalent of having 100 x-rays every day. "We all know that astronauts are under huge radiation stress," Dr. Tai said. "To monitor their blood in space is everybody's dream." The technology also could be used on Earth, he noted. "It should be in every ambulance."

Meanwhile, helping people both on Earth and in space get a good night's sleep without relying on medications is the goal of George Brainard, PhD, professor of neurology at Jefferson Medical College in Philadelphia.

"Even in short flights, astronauts may go from getting seven to eight hours of sleep a night to getting only six or less. Something happens to [their] bodies that leads to sleep reduction," he said.

Although losing an hour per night might not seem too terrible, on a long mission those lost hours could add up to serious deprivation. Dr. Brainard and his colleagues are now working with light treatment to determine whether increasing the power in the short wave length, or the blue portion, of the spectrum can help maintain astronauts' circadian rhythms and keep sleep cycles at an adequate level.

The technique wouldn't just be for outer space. "One-fifth of the working population in the United States and most other industrialized countries does shift work. They are working at a time that they are biologically designed to be sleeping and trying to sleep at a time they are designed to be awake," Dr. Brainard said.