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Cerebral Blood Flow Distribution During Parabolic Flight-induced Microgravity (GraCer)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT03986788
Recruitment Status : Enrolling by invitation
First Posted : June 14, 2019
Last Update Posted : February 25, 2020
Centre National d'Etudes Spatiales
Université de Caen Normandie
The University of New South Wales
Information provided by (Responsible Party):
University Hospital, Caen

Brief Summary:

When astronauts return from space flight, they manifest a set of symptoms, the most striking of which is orthostatic intolerance, that is, the inability to stay upright. This orthostatic intolerance is related to cardiovascular adaptation and disappears in a few days, but the prospect of long-term space travel makes this maladaptation a major concern of space agencies, at a time when there is serious consideration to make " land "a ship on Mars.

Previous studies suggest that brain vessel adaptation may contribute to spatial post-flight orthostatic intolerance. The question remains controversial because not all studies are consistent. These studies are all based on the measurement of blood flow in a single artery of the brain (the average cerebral, see cerebral circulation diagram) easily accessible with a Doppler ultrasound machine. Our team has good reason to believe that the adaptation of the cerebral vessels is not carried out in the same way in all the arteries of the brain and that in particular the arteries that irrigate the posterior and inferior parts of the brain are a major determinant. from cerebrovascular adaptation to orthostatism and that orthostatic intolerance is more specifically related to a decrease in blood flow in these arteries. On the other hand our team has shown that the external carotid artery plays, under certain conditions, a buffer role of the sudden variations of perfusion pressure of the brain.

During the weightless phase of parabolic flight, part of the blood from the legs and abdomen "rises" to the thorax and this transfer of fluid induces changes in blood pressure and cardiac output that affect the cerebral circulation. From a cardiovascular point of view, it is the same thing for a seated subject to lie down, but the parabolic flight offers the unique possibility of achieving this transfer in a fraction of a second and thus allowing to study the immediate response of the cerebral circulation. .

Investigators goal is therefore to quantify the changes in blood flow in the posterior and anterior territories of the brain (transcranial ultrasound) as well as in the internal carotid and vertebral (Doppler ultrasound) during changes in blood pressure and cardiac output induced by transfers. liquid resources associated with the transition to weightlessness.

The oxidative stress generated by weightlessness has been identified as a determining factor in cerebrovascular deconditioning associated with orthostatic intolerance. In order to quantify the biochemical markers of this stress, a venous sample will be taken before and just after the parabolic flight.

Condition or disease Intervention/treatment Phase
Weightlessness Cerebral Blood Flow Other: Weightlessness Not Applicable

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 18 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Intervention Model Description: Comparison of cerebral blood flow in 1G, 1.8 G and 0G conditions
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Effet de l'Impesanteur Sur la Distribution du débit Sanguin cérébral.
Actual Study Start Date : October 1, 2018
Estimated Primary Completion Date : September 30, 2021
Estimated Study Completion Date : September 30, 2021

Arm Intervention/treatment
Weightlessness measurements during flight
Other: Weightlessness
Volunteers will be studied during parabolic flight. Cerebral blood flow will be measured in different part of the brain during weightlessness ans compared to 1g and hypergravity measurements.

Primary Outcome Measures :
  1. Cervical blood flow [ Time Frame: baseline ]

    Measurement of the cervical blood flow in external (ECA), internal (ICA) and vertebral arteries (VA).

    ICA, VA and ECA blood flow velocities will be measured with a color-coded ultrasound system (Vivid-e; GE Healthcare, Tokyo, Japan) equipped with a 10 MHz linear transducer. ICA blood flow measurements will be performed 1.0-1.5 cm distal to the carotid bifurcation while the subject's chin will be slightly elevated. VA blood flow will be measured between the transverse processes of C3 and the subclavian artery. The systolic and diastolic diameters will be measured in detail, and then the mean diameter (in centimetres) will be calculated in relationship to the blood pressure curve, as follows: mean diameter = (systolic diameter×1/3) +(diastolic diameter × 2/3).

  2. Transcranial blood flow [ Time Frame: baseline ]
    Measurement of the transcranial blood flow in anterior (ACA), middle (MCA) and posterior (PCA) cerebral arteries. Blood flow velocities in PCA, MCA and ACA will be measured with an echo-doppler device (Philips CX50, Philips, the Netherlands) using vascular probes adapted to transcranial Doppler. Flows in the different branches of the circle of Willis (ACA-1, MCA-1, PCA-1, ACoA, PCoA) will be used to assess the cerebral hemodynamic indices.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Healthy volunteers (men or women)
  • Aged from 18 to 65
  • Affiliated to a Social Security system and, for non-French resident, holding a European Health Insurance Card (EHIC)
  • Who accepted to take part in the study
  • Who have given their written stated consent
  • Who have passed a medical examination similar to a standard aviation medical examination for private pilot aptitude (JAR FCL3 Class 2 medical examination). There will be no additional test performed for subject selection.

Exclusion Criteria:

  • Persons who took part in a previous biomedical research protocol, of which exclusion period is not terminated.
  • Persons with history of cerebral, cardiovascular or vestibular diseases.
  • Pregnant women (urine pregnancy test for women of childbearing potential)

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT03986788

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Novespace A310-0G
Mérignac, France, 33700
Sponsors and Collaborators
University Hospital, Caen
Centre National d'Etudes Spatiales
Université de Caen Normandie
The University of New South Wales
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Study Director: Christophe Kassel, Hospital Manager University Hospital, Caen
Additional Information:
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Responsible Party: University Hospital, Caen Identifier: NCT03986788    
Other Study ID Numbers: 2018-A01090-55
First Posted: June 14, 2019    Key Record Dates
Last Update Posted: February 25, 2020
Last Verified: February 2020
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: Undecided

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No