Page 181 - International Space Station Benefits for Humanity, 3rd edition.

and the body. Heart rate response to changes in blood confirm if and when insulin resistance, a precursor
pressure varied between astronauts. These results of type 2 diabetes, develops during a space mission,
could point to a need for some crew members to clarify the effect of radiation exposure and track the
do more exercise or use other measures to help recovery process after return on cardiovascular health.
protect their blood pressure response on return to Cardiovascular disease is the number one cause
Earth. CCISS suggested that constant elevation in of death on Earth, where research has associated
blood pressure in the brain while in space, reduced physical inactivity with the development of risk factors,
daily physical activity, and constant exposure to slightly including arterial stiffness and insulin resistance.
higher levels of carbon dioxide in cabin air may impair These spaceflight studies provide a platform to explore
how blood vessels of the brain respond to changes potential mechanisms and help develop interventions
in blood pressure and carbon dioxide levels. to slow vascular aging and improve health and quality
Results from the second experiment, Cardiovascular of life for everyone—regardless of whether their hearts
Health Consequences of Long-Duration Space Flight are free of gravity.
(Vascular), highlighted individual variability in the control
of arterial blood pressure by the hormones in the blood,
with some differences in male and female astronauts. Dressing Astronauts for Return to Earth
Interestingly, some crew members return from the ISS Astronauts on the ISS perform research with mice
with much stiffer arteries than when they went into and spiders, and not a single crew member ever faints.
space. The Vascular study confirmed an increase in When those same astronauts come back to Earth,
carotid artery stiffness indicators, in both male and though, it can be a different story.
female astronauts, of the magnitude expected from
10 to 20 years of normal aging. Arterial stiffening in Postflight orthostatic intolerance, or the inability to
space and on Earth is often linked to an increased maintain blood pressure while in an upright position,
blood pressure and elevated risk for cardiovascular can cause astronauts to faint upon return from space.
disease. Some results from the study revealed that Between 60% and 80% of astronauts experience
insulin resistance occurs during spaceflight, possibly orthostatic intolerance after long-duration missions.
due to reduced physical activity. Insulin resistance on This represents a potential hazard for crew members
Earth leads to increased blood sugar and increased during re-entry and after landing, especially
risk of developing type 2 diabetes. All these results should there be a need for an emergency exit
suggested that the astronauts’ exercise routine was from the spacecraft.
not sufficient to counteract the lifestyle of weightless- Countermeasures such as fluid loading and
ness and pointed to the need for further work on compression garments have demonstrated some
appropriate countermeasures to help maintain effectiveness in preventing this phenomenon.
astronaut health. However, neither is completely effective at all phases
The follow-on study, Cardiac and Vessel Structure and of landing and egress. Therefore, research continues.
Function with Long-Duration Space Flight and Recovery NASA and ROSCOSMOS have used garments that
(Vascular Echo), is examining changes in blood vessels provide lower-body compression as a countermeasure
and the heart while in space and following return to protect astronauts and cosmonauts during and after
to Earth. More specifically, this study will determine return from spaceflight.
how arteries and the heart react to changes in blood A next-generation compression garment design
pressure, whether blood flow after exercise is changed resulted from a series of studies conducted by NASA’s
by spaceflight, and identify warning signs of arterial
stiffening in the blood. This study uses ultrasound and
blood samples to provide immediate feedback on the
development of arterial stiffness and cardiac changes
during spaceflight. It explores a potential measure to NASA continues to improve
reduce the excess amount of blood in the upper body
by using a leg cuff, and less-complicated ways than compression garments that allow
ultrasound to measure changes in arterial stiffness. astronauts to dress for a more
Finally, a fourth study—The space environment causes successful return to Earth.
acceleration of vascular aging: roles of hypogravity,
nutrition and radiation (Vascular Aging)—will try to

167