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A Simple In-flight Method to Test the Risk of Fainting on Return to Earth after Long-duration Space Flight (BP_Reg)
Principal Investigator
Research Area:
Cardiovascular physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

After long-duration space flight, cardiovascular reflexes essential to the normal maintenance of brain blood flow in the upright posture on Earth are depressed and the risk of dizziness and fainting are greatly increased. The investigators proposed a simple test to quantify the changes in blood pressure regulatory mechanisms during space flight. Arterial blood pressure was manipulated by inflating cuffs around the upper legs to temporarily stop blood flow then rapidly releasing the cuffs resulting in a sudden drop in blood pressure. The magnitude of this drop indicates the efficiency of the blood pressure control system. Arterial blood pressure signals provided continuous estimates of cardiac output that were compared to a standard re-breathing method. Data from the leg cuff test conducted before and during flight was used to predict the change in response to a stand test that was conducted shortly after return from space. The investigators hypothesized that astronauts who have large reductions in return of blood to the heart or poor constriction of the arteries would have the poorest response during the post-flight stand test and will benefit the most from aggressive countermeasures before returning to Earth.

Specific Aims:
1. To test the hypothesis that cardiac output calculated from the analysis of the finger blood pressure waveform provides an accurate estimate both pre-flight and in-flight by comparison with a re-breathing method.
2. To test the hypothesis that those astronauts who show the greatest change in blood pressure from pre- to in-flight following the release of leg cuffs will have the greatest decrements in performance in the post-flight stand test.

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Hughson RL, Yee NJ, and Greaves DK. Elevated end-tidal Pco2 during long-duration spaceflight. Aerospace Medicine and Human Performance. 2016. October 1; 87(10): 894-897.

Hughson RL, Shoemaker JK, and Arbeille P. CCISS, Vascular and BP Reg: Canadian space life science research on ISS. Acta Astronautica. 2014. November; 104(1): 444-448. [DOI]

Cardiac output
Arterial pressure
Blood pressure

Photo Gallery
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Data Information
Data Availability
Archive is complete. No data sets are available for this experiment. Please Contact LSDA if you know of available data for this investigation.

Aortic blood flow velocity
Aortic diameter
Blood pressure
Central venous pressure
Exercise, duration
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Expedition 33 09/16/2012 11/18/2012 63 days
Expedition 34 11/18/2012 03/15/2013 117 days
Expedition 35 03/15/2013 05/13/2013 58 days
Expedition 36 05/13/2013 09/10/2013 166 days
Expedition 37 09/10/2013 11/10/2013 61 days
Expedition 38 11/10/2013 03/10/2014 120 days
Expedition 40 05/13/2014 09/10/2014 133 days
Expedition 41 09/10/2014 11/09/2014 29 days
Expedition 42 11/10/2014 03/11/2015 121 days
Expedition 43 03/11/2015 06/10/2015 91 days
Expedition 44 06/10/2015 09/11/2015 93 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Jessica Keune
Institutional Support
Canadian Space Agency (CSA)
Alternate Experiment Name
Proposal Source