Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
SHR Neuro Krebs Kardio Lipid Stoffw Microb
Blaber, AP; Goswami, N; Bondar, RL; Kassam, MS.
Impairment of cerebral blood flow regulation in astronauts with orthostatic intolerance after flight.
Stroke. 2011; 42(7):1844-1850
Doi: 10.1161/STROKEAHA.110.610576
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- Co-Autor*innen der Med Uni Graz
- Goswami Nandu
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- Abstract:
- Background and Purpose-We investigated cerebral blood flow regulation in astronauts before and after flights. We hypothesized that autoregulation would be different before flight and after flight between nonfinishers and the finishers of a stand test. Methods-Twenty-seven astronauts from shuttle missions lasting 8 to 16 days underwent a 10-minute stand test: 10 days before flight, 1 to 2 hours and 3 days after landing. Mean blood flow velocity of the middle cerebral artery (MCA) was measured using transcranial Doppler; Mean arterial pressure was measured using a Finapres (Ohmeda, Englewood, CO) and was adjusted to the level of the MCA (BP(MCA)). Cross-spectral power, gain, phase, and coherence were determined for the relation between BP(MCA) and the cerebrovascular resistance index mean blood flow velocity/BP(MCA). Results-BP(MCA) was reduced with stand (P < 0.001). Differences between finishers and nonfinishers (P = 0.011) and over test days (P = 0.004) were observed. Cerebrovascular conductance was affected by stand (P < 0.001), by group (P < 0.001) with a group by stand, and test day interaction (P < 0.01). Preflight data suggest that the nonfinishers were operating at a higher cerebral vasodilation than finishers for a given BP(MCA), and on landing day the nonfinishers had a greater decrease in mean blood flow velocity as a function of BP(MCA) with standing compared to finishers and preflight. There was a significant interaction effect of gender over the test days and from supine to stand (P = 0.035). Conclusions-Our results indicate that the cause of presyncope in astronauts may be related to a mismatch of cerebral blood flow with blood pressure. Astronaut gender may also play a role in susceptibility to orthostatic intolerance after flight. (Stroke. 2011; 42: 1844-1850.)
- Find related publications in this database (using NLM MeSH Indexing)
- Astronauts -
- Blood Circulation Time -
- Blood Flow Velocity -
- Blood Pressure -
- Cerebrovascular Circulation - physiology
- Female -
- Humans -
- Male -
- Middle Cerebral Artery - ultrasonography
- Orthostatic Intolerance - diagnosis
- Sex Factors -
- Space Flight -
- Syncope - etiology
- Time Factors -
- Ultrasonography, Doppler - methods
- Find related publications in this database (Keywords)
- cerebral blood flow
- cerebral hemodynamics
- microgravity
- gender
- transcranial Doppler