Central and regional hemodynamics in prolonged space flights

Area of Science:

• Space physiology
• Cardiovascular research
• Human adaptation to microgravity

Background:

• Understanding cardiovascular changes during spaceflight is crucial for astronaut health.
• Previous studies have indicated alterations in central and regional hemodynamics in microgravity.
• Long-duration space missions pose unique challenges to the human circulatory system.

Purpose of the Study:

• To measure central and regional hemodynamics in astronauts during short-term and long-term space missions.
• To assess cardiovascular responses to provocative tests like lower body negative pressure (LBNP) and exercise.
• To investigate the impact of microgravity on blood flow and vascular tone in different body regions.

Main Methods:

• Tetrapolar rheography was used to measure hemodynamics at rest and during tests.
• Data collected from Salyut-6 and Salyut-7 manned missions (short-term and long-term flights).
• Evaluated stroke volume (SV), cardiac output (CO), heart rate (HR), and regional pulse blood filling (PBF).

Main Results:

• At rest, SV and CO showed insignificant changes or remained stable during long-term flights.
• Exercise tests in prolonged flights increased CO due to higher HR, with unchanged SV.
• Regional changes included decreased calf PBF, reduced vascular tone in calves and forearms, and altered cerebral blood flow and tone.

Conclusions:

• Regional circulation variations in microgravity are dependent on the specific body area examined.
• Spaceflight induces a rearrangement of total human body hemodynamics.
• Findings highlight the complex adaptation of the cardiovascular system to prolonged exposure to microgravity.