Cerebral Blood Flow Distribution During Parabolic Flight-induced Microgravity

NCT03986788 | Unknown

• 1 other identifier: 2018-A01090-55
• Study Type: interventional
• Target: 18
• Locations: 1 country
• Sites: 1

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.

Conditions

Weightlessness; Cerebral Blood Flow

Outcome Measures

Primary Outcomes (2)

• Cervical blood flow

  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).

  baseline

• Transcranial blood flow

  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.

  baseline

Study Arms (1)

Weightlessness

OTHER

Weightlessness measurements during flight

Other: Weightlessness

Interventions

Weightlessness OTHER

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.

Weightlessness

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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.

You may not qualify if:

• Persons with history of cerebral, cardiovascular or vestibular diseases.
• Pregnant women (urine pregnancy test for women of childbearing potential)

Sponsors & Collaborators

• University Hospital, Caen: lead
• Centre National d'Etudes Spatiales: collaborator
• Université de Caen Normandie: collaborator
• The University of New South Wales: collaborator

Study Sites (1)

Novespace A310-0G

Mérignac, 33700, France

Location

Related Links

• Site for weightlessness experimentations

MeSH Terms

Interventions

Weightlessness

Intervention Hierarchy (Ancestors)

Hypogravity; Gravity, Altered; Gravitation; Astronomical Phenomena; Physical Phenomena

Study Officials

• Christophe Kassel, Hospital Manager

  University Hospital, Caen

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Comparison of cerebral blood flow in 1G, 1.8 G and 0G conditions

Study Record Dates

• First Submitted: May 23, 2019
• First Posted: June 14, 2019
• Study Start: October 1, 2018
• Primary Completion: September 30, 2021
• Study Completion: September 30, 2021
• Last Updated: February 25, 2020

Record last verified: 2020-02

Locations

FR (1)