Human Cerebral Autoregulation during Long-duration Spaceflight (Cerebral Autoregulation) - 01.10.18

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
As the body’s most important organ, the brain needs a strong and reliable blood supply, so the brain is capable of self-regulating blood flow even when the heart and blood vessels cannot maintain an ideal blood pressure. The Cerebral Autoregulation investigation tests whether this self-regulation improves in the microgravity environment of space. Non-invasive tests measure blood flow in the brain before, during, and after a long-duration spaceflight, and provide new insights into how the brain safeguards its blood supply in a challenging environment.
Science Results for Everyone
Information Pending

The following content was provided by Dai Shiba, and is maintained in a database by the ISS Program Science Office.
Information provided courtesy of the Japan Aerospace and Exploration Agency (JAXA).
Experiment Details

OpNom: Cerebral Autoregulation

Principal Investigator(s)
Kenichi Iwasaki, M.D., Ph.D., Nihon University School of Medicine, Tokyo, Japan

Co-Investigator(s)/Collaborator(s)
Yojiro Ogawa, D.D.S., Ph.D., Nihon University School of Medicine, Tokyo, Japan
Ken Aoki, M.D., Ph.D., Nihon University School of Medicine, Tokyo, Japan
Ryo Yanagida, M.D., Ph.D., Nihon University School of Medicine, Tokyo, Japan
Takuya Kurazumi, M.D., Keio University School of Medicine, Tokyo, Japan
Benjamin D. Levine, M.D., Institute for Exercise and Environmental Medicine, University of Texas Southwestern Medical Center, Presbytyrian Hospital, Dallas, TX, United States

Developer(s)
European Space Agency (ESA), Noordwijk, Netherlands
Japan Aerospace Exploration Agency, Space Environment Utilization Center, Tsukuba, Japan

Sponsoring Space Agency
Japan Aerospace Exploration Agency (JAXA)

Sponsoring Organization
Japan Aerospace Exploration Agency

Research Benefits
Space Exploration, Earth Benefits, Scientific Discovery

ISS Expedition Duration
September 2017 - February 2018; -

Expeditions Assigned
53/54,55/56

Previous Missions
Related investigation: Neurolab Mission (STS-90) and IPVI (ISS from Inc.43/44)

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Experiment Description

Research Overview

• The human brain, as the most important organ in the body, requires a high blood flow supply. The brain blood flow regulation system must rapidly adjust the brain’s blood vessels to maintain blood flow to the brain, when the cardiovascular system cannot perfectly maintain arterial blood pressure. The changes in the regulation of brain blood flow may be related to “fainting after spaceflight” frequently seen in astronauts.
• In the Cerebral Autoregulation investigation, the changes in the capacity of maintaining brain blood flow during short- and long-term spaceflight are estimated.
• Improved regulation for brain blood flow may be the compensatory mechanism for the brief loss of consciousness and lightheadedness that many astronauts experience in the upright posture after space flight. The findings from this investigation could have broad application to medicine, both for astronauts and syncope patients on earth.

Description

From previous experiments Neurolab mission aboard the Space Shuttle (STS-90), it was hypothesized that human cerebral autoregulation is preserved, and possibly even improved by 2 weeks in space. Moreover, prolonged space-flight may progressively improve human cerebral autoregulation more. The purpose of the Cerebral Autoregulation investigation is to determine the effects of short and long-duration spaceflight on cerebral blood flow autoregulation in human, testing the above hypothesis.
 
Waveforms of arterial blood pressure in the finger artery, and blood flow velocity in middle cerebral artery, are measured before, during, and after long-term spaceflight using the Portable Doppler (PDOP). The PDOP is European Space Agency (ESA) hardware that is used to obtain waveforms of blood flow velocity in the middle cerebral artery, and records this data by non-invasive measurement. Cardiopres is another piece of ESA hardware, used to obtain waveforms of continuous arterial blood pressure by non-invasive measurement. The linear dependence of middle cerebral artery flow velocity on arterial blood pressure is to be estimated, as well as the magnitude of transfer from arterial blood pressure to middle cerebral artery flow velocity.
 
The estimated result is that long-duration spaceflight decreases the linear dependence of middle cerebral artery flow velocity on arterial blood pressure, and the magnitude of transfer from arterial blood pressure to middle cerebral artery flow velocity. If so, the results imply an improvement of dynamic cerebral autoregulation by long-duration spaceflight. This adaptation would play an important role to counteract decreases in cerebral perfusion pressure when the cardiovascular system cannot perfectly maintain arterial blood pressure after space flight. The determination of the effects of spaceflight on the autoregulation of cerebral blood flow is scientifically interesting, and important to human spaceflight.

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Applications

Space Applications
After returning to Earth, many astronauts faint or experience lightheadedness, which may be related to changes in blood flow in the brain. Understanding how these blood flows change improves efforts to treat this space-related lightheadedness, including possible countermeasures.

Earth Applications
When the brain cannot compensate for a sudden drop in blood pressure, a person will become lightheaded or briefly lose consciousness in a fainting episode. This is known as syncope, and it affects millions of people worldwide. Understanding how to improve the brain’s self-regulation of blood flow would benefit these patients, as well as future space travelers.

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Operations

Operational Requirements and Protocols

Hardware checkout
Equipment and JAXA unique configuration will be checked out in ISS prior to the human experiment without human subject.
Number of subjects: 6 crew members
 
In flight
The data collected is to be downlinked to the ground for analysis. No required samples are needed. Constraints for subjects are: Activity 1 is conducted at L+14 days (-7/+0day), Activity 2 is conducted at 4 weeks (-1/+1 week), Activity 3 is conducted at 16 weeks (-1/+1 week). No exercise including VO2 Max should be performed within 12 hours before each activity. No EVA should be performed for 12 hours prior to the session. More than 1 hour should be elapsed after nitroglycerin, catecholamines, etc. No caffeine or nicotine for 12 hours prior to testing. No heavy meal within the last 4 hours before performing experiment. A light snack of complex carbohydrates is OK within 2 hours of testing.
 
The hardware checkout and Man-in Loop Testing which include the measurement of cerebral blood flow velocity, blood pressure, and ECG will be conducted in advance of the first session.
 
Pre and Post-BDC
Constraints for subjects are: Crews whose Arterial Blood Pressure (ABP) and Cerebral Blood Flow Velocity (CBFV) wave form can be measured (check at precheck session). No maximal exercise including VO2 Max, and NBL within 12 hours before each BDC session. More than 1 hour should be elapsed after nitroglycerin, catecholamines, etc. No caffeine, nicotine, or alcohol for 12 hours prior to testing. No heavy meal within the last 4 hours before performing experiment. A light snack of complex carbohydrates is OK within 2 hours of testing. Other medicine and exercise logs of subjects for 6 hours prior to testing are required, if acceptable. In addition, as secondary evaluation, intracranial pressure will be estimated using pre/post flight data of high resolution waveforms with increased high frequency.
The following data sharing are requested;
Mandatory:
 • Diagnosis of optic disc edema (MEDB 1.10) pre-/ in-/post-flight.
 o ( e.g. Fundoscopy, Vision Testing, Ultrasound, and MRI reports, including clinical specialist diagnosis)
 
If available:
 • Ophthalmology/Optometry (MEDB 1.10) reports pre-/in-/post-flight.
 o (Vision Testing (pre/post), Visual Acuity (inflight), which measure amsler grid, visual fields, visual acuity changes, and refractive micropsia)
 • Laboratory Testing (MEDB2.1)
 o (e.g. Hemoglobin (Hb), Hematocrit (Ht), Red Blood Cell (RBC), etc.)
 • On-Orbit Strength & Conditioning Monitoring (MEDB 5.2),
 o (e.g. Number of training sessions/week, etc.)
 • Medication history at pre-/in-/post-flight,
 o (e.g. logs of 6 hours prior to each BDC and in-flight, etc.)
Orthostatic tolerance (MEDB4.2)
 
1. Prepare Personal Computer (PC).
2. Measure blood flow velocity in middle cerebral artery, and continuous arterial blood pressure, 3 times. (L+2 weeks, L+1 month, L+4 months).
3. PC Close Out.
4. Data down link.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Information Pending

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Related Websites

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Imagery