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aero space-medicine

Space medicine

Space medicine is the practice of medicine on astronauts in outer space.

Who benefits from space medicine research?

Astronauts are not the only ones who benefit from space medicine research. Several medical products have been developed that are space spinoffs, that is practical applications for the field of medicine arising out of the space program. Because of joint research efforts between NASA, the National Institutes on Aging (a part of the National Institutes of Health), and other aging-related organizations, space exploration has benefitted a particular segment of society, seniors. Evidence of aging related medical research conducted in space was most publicly noticeable during STS-95 (See below).

Medical space spinoffs from the early space exploration years (pre-Mercury through Apollo projects)

  • Radiation therapy for the treatment of cancer. In conjunction with Cleveland Clinic,

the cyclotron at NASA’s center in Cleveland, Ohio—which had been utilized for testing nuclear propulsion systems for air and space craft—was used in the first clinical trials for the treatment and evaluation of neutron radiation therapy for cancer patients.

  • Foldable walkers. Made from a lightweight metal material developed by NASA for aircraft and spacecraft, foldable walkers are portable and easy to manage.
  • Personal alert systems. These are emergency alert devices that can be worn by individuals who may require emergency medical or safety assistance. When a button is pushed, the device sends a signal to a remote location for help. To send the signal, the device relies on telemetry technology developed at NASA.
  • CAT Scans and MRIs. These devices are used by hospitals to see inside the human body. Their development would not have been possible without the technology provided by NASA after it found a way to take better pictures of the Earth’s moon.
  • Muscle stimulator device. This device is used for ½ hour per day to prevent muscle atrophy in paralyzed individuals. It provides electrical stimulation to muscles which is equal to jogging three miles per week. Christopher Reeves used these in his therapy.
  • Orthopedic evaluation tools. Equipment to evaluate posture, gait, and balance disturbances was developed at NASA, along with a radiation-free way to measure bone flexibility using vibration.
  • Diabetic foot mapping. This technique was developed at NASA’s center in Cleveland, Ohio to help monitor the effects of diabetes in feet. These efforts helped
  • Foam cushioning. Special foam used for cushioning astronauts during liftoff is used in pillows and mattresses at many nursing homes and hospitals to help prevent ulcers, relieve pressure, and provide a better night’s sleep.
  • Kidney dialysis machines. These machines rely on technology developed by NASA in order to process and remove toxic waste from used dialysis fluid.
  • Talking wheelchairs. Paralyzed individuals who have difficulty speaking may use a talking feature on their wheelchairs which was developed by NASA to create synthesized speech for aircraft.
  • Collapsible, lightweight wheelchairs. These wheelchairs are designed for portability and can be folded and put into trunks of cars. They rely on synthetic materials that NASA developed for its air and space craft
  • Surgically implantable heart pacemaker. These devices depend on technologies developed by NASA for use with satellites. They communicate information about the activity of the pacemaker, such as how much time remains before the batteries need to be replaced.
  • Implantable heart defibrillator. This tool continuously monitors heart activity and can deliver an electric shock to restore heartbeat regularity.
  • EMS Communications. Technology used to communicate telemetry between Earth and space was developed by NASA to monitor the health of astronauts in space from the ground. Ambulances use this same technology to send information—like EKG readings—from patients in transport to hospitals. This allows faster and better treatment.
  • Weightlessness. While not an invention per se, the weightlessness of space one day may allow individuals with limited mobility on Earth--even those normally confined to wheelchairs--the freedom to move about with ease. A notable individual to take advantage of weightlessness in the "Vomit Comet" during 2007 was physicist Stephen Hawking.

Major historical medical investigations in space during the Space Shuttle era

STS-95

John Glenn, the first American astronaut to orbit the Earth, returned with much fanfare to space once again at 77 years of age to confront the physiological challenges preventing long-term space travel for astronauts—loss of bone density, loss of muscle mass, balance disorders, sleep disturbances, cardiovascular changes, and immune system depression—all of which are problems confronting aging people as well as astronauts. Once again Glenn stepped forward to play an historic role in the future of space exploration, but this time he would provide new medical research in the field of gerontology as well.

What are the effects of space on the body?

Accident investigation

Decompression sickness

Decompression illness in spaceflight

In space, astronauts use a space suit, essentially a self-contained individual spacecraft, to do spacewalks, or extra-vehicular activities (EVAs). Spacesuits are generally inflated with 100% oxygen at a total pressure that is less than a third of normal atmospheric pressure. Eliminating inert atmospheric components such as nitrogen allows the astronaut to breathe comfortably, but also have the mobility to use their hands, arms, and legs to complete required work, which would be more difficult in a higher pressure suit.

After the astronaut dons the spacesuit, air is replaced by 100% oxygen in a process called a "nitrogen purge". In order to reduce the risk of decompression sickness, the astronaut must spend several hours "pre-breathing" at an intermediate nitrogen partial pressure, in order to let their body tissues outgas nitrogen slowly enough that bubbles are not formed. When the astronaut returns to the "shirt sleeve" environment of the spacecraft after an EVA, pressure is restored to whatever the operating pressure of that spacecraft may be, generally normal atmospheric pressure. Decompression illness in spaceflight consists of decompression sickness (DCS) and other injuries due to uncompensated changes in pressure, or barotrauma.

Decompression sickness

Decompression sickness is the injury to the tissues of the body resulting from the presence of nitrogen bubbles in the tissues and blood. This occurs due to a rapid reduction in ambient pressure causing the dissolved nitrogen to come out of solution as gas bubbles. In space the risk of DCS is significantly reduced by using a technique to wash out the nitrogen in the body’s tissues. This is achieved by breathing 100% oxygen for a specified period of time before donning the spacesuit, and is continued after a nitrogen purge. DCS may result from inadequate or interrupted pre-oxygenation time, or other factors including the astronaut’s level of hydration, physical conditioning, prior injuries and age. Other risks of DCS include inadequate nitrogen purge in the EMU, a strenuous or excessively prolonged EVA, or a loss of suit pressure. Non-EVA crewmembers may also be at risk for DCS if there is a loss of spacecraft cabin pressure.

Symptoms of DCS in space may include chest pain, shortness of breath, cough or pain with a deep breath, unusual fatigue, lightheadedness, dizziness, headache, unexplained musculoskeletal pain, tingling or numbness, extremities weakness, or visual abnormalities.

Primary treatment principles consist of in-suit repressurization to re-dissolve nitrogen bubbles, 100% oxygen to re-oxygenate tissues, and hydration to improve the circulation to injured tissues.

To date there have been no reported cases of DCS in the NASA space program.

Barotrauma

Barotrauma is the injury to the tissues of air filled spaces in the body as a result of differences in pressure between the body spaces and the ambient atmospheric pressure. Air filled spaces include the middle ears, parananal sinuses, lungs and gastrointestinal tract. One would be predisposed by a pre-existing upper respiratory infection, nasal allergies, recurrent changing pressures, dehydration, or a poor equalizing technique.

Positive pressure in the air filled spaces results from reduced barometric pressure during the depressurization phase of an EVA. It can cause abdominal distension, ear or sinus pain, decreased hearing, and dental or jaw pain. Abdominal distension can be treated with extending the abdomen, gentle massage and encourage passing flatus. Ear and sinus pressure can be relieved with passive release of positive pressure. Pretreatment for susceptible individuals can include oral and nasal decongestants, or oral and nasal steroids.

Negative pressure in air fill spaces results from increased barometric pressure during repressurization after an EVA or following a planned restoration of a reduced cabin pressure. Common symptoms include ear or sinus pain, decreased hearing, and tooth or jaw pain.

Treatment may include active positive pressure equalization of ears and sinuses, oral and nasal decongestants, or oral and nasal steroids, and appropriate pain medication if needed.

References

Altitude Decompression Sickness Susceptibility, MacPherson, G; Aviation, Space, and Environmental Medicine, Volume 78, Number 6, June 2007 , pp. 630-631(2)

Decision Analysis in Aerospace Medicine: Costs and Benefits of a Hyperbaric Facility in Space, John-Baptiste, A; Cook, T; Straus, S; Naglie, G; et al. Aviation, Space, and Environmental Medicine, Volume 77, Number 4, April 2006 , pp. 434-443(10)

Incidence of Adverse Reactions from 23,000 Exposures to Simulated Terrestrial Altitudes up to 8900 m, DeGroot, D; Devine JA; Fulco CS; Aviation, Space, and Environmental Medicine, Volume 74, Number 9, September 2003 , pp. 994-997(4)

Decreased immune system functioning

Astronauts in space have weakened immune systems, which means that in addition to increased vulnerability to new exposures, viruses already present in the body—which would normally be suppressed—become active. In space, T-cells (a part of white blood cells that produces antibodies) do not reproduce properly. T-cells that do exist are less able to fight off infection. NASA research is measuring the change in the immune systems of its astronauts as well as performing experiments with T-cells in space.

Effects of fatigue

Human performance

Loss of balance

Leaving and returning to Earth’s gravity causes “space sickness,” dizziness, and loss of balance in astronauts. By studying how changes can affect balance in the human body--involving the senses, the brain, the inner ear, and blood pressure--NASA hopes to develop treatments that can be used on Earth and in space to correct balance disorders. Until then, NASA’s astronauts must rely on a medication called Midodrine (an “anti-dizzy” pill that temporarily increases blood pressure) to help carry out the tasks they need to do to return home safely.

Loss of bone density

Unlike people with osteoporosis, astronauts eventually regain their bone density. After a 3-4 month trip into space, it takes about 2-3 years to regain lost bone density. New techniques are being developed to help astronauts recover faster. Research in the following areas holds the potential to aid the process of growing new bone:

  • Diet and Exercise changes may reduce osteoporosis.
  • Vibration Therapy may stimulate bone growth.
  • Medication could trigger the body to produce more of the protein responsible for bone growth and formation.

Loss of muscle mass

In space, muscles in the legs, back, spine, and heart weaken and waste away because they no longer are needed to overcome gravity, just as people lose muscle when they age due to reduced physical activity. Astronauts rely on research in the following areas to build muscle and maintain body mass:

  • Exercise may build muscle if at least two hours a day is spent doing resistance training routines.
  • Hormone supplements (hGH) may be a way to tap into the body’s natural growth signals.
  • Medication may trigger the body into producing muscle growth proteins.

Man-machine interface

Orthostatic intolerance

In space, astronauts lose fluid volume—including up to 22% of their blood volume. Because it has less blood to pump, the heart will atrophy. A weakened heart results in low blood pressure and can produce a problem with “orthostatic tolerance,” or the body’s ability to send enough oxygen to the brain without fainting or becoming dizzy. "Under the effects of the earth's gravity, blood and other body fluids are pulled towards the lower body. When gravity is taken away or reduced during space exploration, the blood tends to collect in the upper body instead, resulting in facial edema and other unwelcome side effects. Upon return to earth, the blood begins to pool in the lower extremities again, resulting in orthostatic hypotension.

Psychological factors

Radiation effects

Safety/habitability

Sleep disorders

Fifty percent of space shuttle astronauts take sleeping pills and still get two hours less sleep. NASA is researching two areas which may provide the keys to a better night’s sleep, as improved sleep decreases fatigue and increases daytime productivity:

  • Environmental cues and practices may be able to retrain the body’s circadian rhythm.
  • Medication could improve sleep by increasing the production of melatonin, a sleep hormone

Spatial disorientation

Medical interventions

How does one prepare for a career in space medicine?

Educational programs

Related degrees, areas of specialization, and certifications

  • Aeromedical certification
  • Aerospace Medicine
  • Aerospace Studies
  • Emergency Medicine
  • Family Practice
  • Internal Medicine
  • Occupational and Preventive Medicine
  • Ophthalmology
  • Otolaryngology
  • Public Health

Professional organizations

Commercial spaceflight medicine

Three major institutions teamed up to investigate space medicine applications in commercial spaceflight. The directors of those programs are listed.

  • Mayo Clinic-Scottsdale - (Dr. Jan Stepanek)
  • University of Texas Medical Branch at Galveston (UTMB) - (Dr. Richard Jennings)
  • Wyle Laboratories Commercial Spaceflight Service Unit - (Dr. Vernon McDonald)
  • National Space Biomedical Research Institute (NSBRI) Space Medicine Liaison at Baylor College of Medicine - (Dr. Jonathan Clark)

Legal aspects of space medicine research

  • Authorities: Professor Joanne Irene Gabrynowicz, space law specialist from the University of Mississippi Space Law Center, and Director of the National Remote Sensing and Space Law Center.
  • Publications: Journal of Space Law

External links

References

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