Fluid Shifts Before, During and After Prolonged Space Flight and Their Association with Intracranial Pressure and Visual Impairment (Fluid Shifts) - 11.30.16

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

ISS Science for Everyone

Science Objectives for Everyone
More than half of American astronauts experience vision changes and anatomical alterations to parts of their eyes during and after long-duration spaceflight. It is hypothesized that the headward fluid shift that occurs during space flight leads to increased pressure in the brain, which may push on the back of the eye, causing it to change shape.  The Fluid Shifts Before, During, and After Prolonged Space Flight and Their Association with Intracranial Pressure and Visual Impairment (Fluid Shifts) investigation measures how much fluid shifts from the lower body to the upper body, in or out of cells and blood vessels, and determines the impact these shifts have on fluid pressure in the head, changes in vision and eye structures.
Science Results for Everyone
Information Pending

The following content was provided by Michael B. Stenger, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: Fluid Shifts

Principal Investigator(s)
Michael B. Stenger, Ph.D., KBRwyle, Houston, TX, United States
Scott A. Dulchavsky, M.D., Ph.D., Henry Ford Hospital, Detroit, MI, United States
Alan R. Hargens, Ph.D., University of California San Diego, San Diego, CA, United States

Co-Investigator(s)/Collaborator(s)
Steven S. Laurie, Ph.D., KBRwyle, Houston, TX, United States
L. Christine Ribeiro, KBRwyle, Houston, TX, United States
Richard Danielson, Ph.D., Universities Space Research Association, Houston, TX, United States
Douglas Ebert, Ph.D., KBRwyle, Houston, TX, United States
Stuart M. C. Lee, Ph.D., KBRwyle, Houston, TX, United States
Brandon R. Macias, Ph.D., KBRwyle, San Diego, CA, United States
David S. Martin, RDMS, RDCS, KBRwyle, Houston, TX, United States
Steven H. Platts, Ph.D., NASA Johnson Space Center, Houston, TX, United States
Robert J. Ploutz-Snyder, Ph.D., University of Michigan School of Nursing, Ann Arbor, MI, United States
Scott M. Smith, Ph.D., NASA Johnson Space Center, Houston, TX, United States
Ashot E. Sargsyan, M.D., KBRwyle, Houston, TX, United States
Philippe Arbeille, M.D., Universite Francois-Rabelais, Tours, France
John H. K. Liu, University of California San Diego Medical Center, San Diego, CA, United States
Kathleen M. Garcia, KBRwyle, Houston, TX, United States
Babs Soller, UMass Med School, Reflectance Medical, Inc & Sotera Wireless, Inc., MA, United States
Smith L. Johnston, M.D., NASA Johnson Space Center, Houston, TX, United States
Valery V. Bogomolov, M.D., Ph.D., Institute for Biomedical Problems, Moscow, Russia
Eugenia N. Yarmanova, Institute of Biomedical Problems, Moscow, Russia
Irina V. Alferova, Ph.D., M.D., Institute for Biomedical Problems, Moscow, Russia
Lawrence Minkoff, Ph.D., Fonar Corporation, Melville, NY, United States

Developer(s)
NASA Johnson Space Center, Human Research Program, Houston, TX, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
NASA Research Office - Human Research Program (NASA Research-HRP)

Research Benefits
Scientific Discovery, Space Exploration, Earth Benefits

ISS Expedition Duration
March 2015 - March 2016; March 2016 - February 2017; March 2017 - September 2017

Expeditions Assigned
43/44,45/46,47/48,49/50,51/52

Previous Missions
Information Pending

^ back to top

Experiment Description

Research Overview

  • More than half of American astronauts have developed ocular refraction changes after long duration space flights. Findings have also included structural changes of the eye, as well as signs of elevated intracranial pressure. While short duration space flight is also characterized by vision disturbances, these are generally transient and do not appear to have lasting impacts on the structure or function of the eye.
  • Changes in vision and eye structure are thought to be the result of prolonged exposure to space flight-induced headward fluid shifts and elevated intracranial pressure. However, this hypothesis has never been systematically tested. The purpose of this investigation is to characterize the space flight-induced fluid shift, including intra- and extravascular shifts, intra- and extracellular shifts, changes in total body water and lower vs. upper body shifts. Noninvasive techniques are used to assess arterial and venous dimensions and flow parameters, ocular pressure and structure, and changes in intracranial pressure.
  • Lower body negative pressure is being investigated for its ability to mitigate some of the effects of the space flight-induced fluid shift.
  • Results from this investigation are expected to help define the causes of the ocular structure and vision changes associated with long duration space flight, and assist in the development of countermeasures.

Description

More than half of American astronauts have developed ocular refraction change after long duration space flight on the International Space Station (ISS). Findings have also included structural changes of the eye (papilledema, globe flattening, choroidal folds) and the optic nerve (sheath dilation, tortuosity and kinking), as well as imaging signs and lumbar puncture data indicative of elevated intracranial pressure (ICP). This pattern is referred to as the visual impairment and intracranial pressure (VIIP) syndrome. While short duration space flight is also characterized by vision disturbances, these are generally transient and do not appear to have lasting impacts on the structure or function of the eye. Changes in vision, eye and adnexa morphology, are hypothesized to be the result of space flight-induced cephalad fluid shifts and elevated intracranial pressure. This hypothesis, however, has not been systematically tested. In earlier anecdotal publications, ICP elevation in long-duration space flight has been inferred, but without association with structural or functional changes of the eye. Furthermore, while fluid shifts and compartmentalization during short duration space flight (Space Shuttle missions) have been studied, the fluid distribution patterns and their effects on intracranial pressure or the structure and function of the sensory organs in the course of long-duration space flight are not well known.

The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight, and to correlate these findings with vision changes and other elements of the VIIP syndrome. The investigators also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as the VIIP-related effects of those shifts, is predicted by the crewmember’s preflight conditions and responses to acute hemodynamic manipulations (such as head-down tilt). Lastly, the patterns of fluid distribution in ISS astronauts during acute reversal of fluid shifts are evaluated through application of lower body negative pressure (LBNP) interventions to characterize and explain general and individual responses.

This experiment examines a variety of physiologic variables in 10 long-duration ISS crewmembers before, during and after long duration space flight. Measures include: (1) fluid compartmentalization (total body water by 2H2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, calcaneus tissue thickness (by ultrasound) ; (3) vascular dimensions by ultrasound (jugular veins, cerebral and carotid arteries, vertebral arteries and veins, portal vein); (4) vascular dynamics by MRI (head/neck blood flow, cerebrospinal fluid pulsatility); (5) ocular measures (optical coherence tomography, intraocular pressure, 2-dimensional ultrasound including optic nerve sheath diameter, globe flattening, and retina-choroid thickness, Doppler ultrasound of ophthalmic and retinal arteries, and veins); (6) cardiac variables by ultrasound (inferior vena cava, tricuspid flow and tissue Doppler, pulmonic valve, stroke volume, right heart dimensions and function, four-chamber views); and (7) ICP measures (tympanic membrane displacement, distortion-product otoacoustic emissions, and optic nerve sheath diameter). On the ground, acute head-down tilt induces cephalad fluid shifts, whereas LBNP opposes these shifts. Controlled Mueller maneuvers are used to manipulate cardiovascular variables. Through interventions applied before, during, and after flight, the relationship between fluid shifts and the VIIP syndrome can be fully evaluated.

^ back to top

Applications

Space Applications
Fluid Shifts investigates the causes for severe and lasting physical changes to astronaut's eyes. Because the headward fluid shift is a hypothesized contributor to these changes, reversing this fluid shift with a lower body negative pressure device is being investigated as a possible intervention. Results from this study may help to develop preventative measures against lasting changes in vision and eye damage.

Earth Applications
Results from the Fluid Shifts investigation are expected to improve scientists' understanding of how blood pressure in the brain affects eye shape and vision, which could also benefit people confined to long-term bed rest, or suffering from disease states that increase swelling and pressure in the brain.

^ back to top

Operations

Operational Requirements and Protocols

The Fluid Shifts experiment requires 10 subjects. Dilution Measures occur at Flight Day (FD) 45 and Return minus 45 for mission durations of six months, with an additional collection at FD 150 for subjects with a mission duration of one year. The Imaging Measures baseline activity is planned within 10 days of each performance of Dilution Measures collections and the Lower Body Negative Pressure (LBNP) Imaging Measures are completed within 30 days of Dilution Measures operations. There is a requirement for real-time data downlink for remote guidance for all ultrasound, OCT, and IOP scans. Additional medical monitoring requirements are in place for the LBNP collections using the Russian Chibis. An additional crewmember acting as an on-orbit medical monitor and real-time monitoring of physiological data on the ground are required during these sessions. Also, LBNP is limited to no more than 60 minutes at a time, resulting in the split of the LBNP collections over 2 days in-flight.

Dilution Measures includes determination of fluid compartmentalization via assessment of total body water (via saliva and urine analysis) and extracellular and intracellular fluid volume (via blood and urine analysis).  The Imaging Measures Baseline activities use various hardware to measure a multitude of anatomical and physiological data points:

  • Ultrasound measures of fluid shifts:
    • Arterial and venous measures of head and neck
    • Cardiac, ophthalmic, and portal vein measures
    • Tissue thickness of lower and upper body
  • Other physiological measures:
    • Intracranial Pressure (CCFP/DPOAE)
    • Intraocular Pressure (Tonopen/iCare and Ultrasound)
    • Ocular Structure (OCT)
    • Blood Pressure / Heart Rate / Vascular Resistance

The LBNP Imaging Measures are a repeat of a subset of the Baseline data points, excluding those that are not available due to the subject wearing Chibis. 
 

^ back to top

Decadal Survey Recommendations

Information Pending

^ back to top

Results/More Information

Information Pending

^ back to top

Results Publications

^ back to top

Ground Based Results Publications

^ back to top

ISS Patents

^ back to top

Related Publications

    Macias BR, Liu J, Grande-Gutierrez N, Hargens AR.  Intraocular and intracranial pressures during head-down tilt with lower body negative pressure. Aviation, Space, and Environmental Medicine. 2015 January 1; 86(1): 3-7. DOI: 10.3357/AMHP.4044.2015. PMID: 25565526.

^ back to top

Related Websites

^ back to top


Imagery

image
NASA Image: ISS043E276208 - Scott Kelly uses ultrasound to image his jugular vein with the aid of Gennady Padalka, in order to evaluate the effectiveness of a lower body negative pressure countermeasure (Chibis LBNP, controlled by Mikhail Kornienko) used to reverse the headward fluid shift that occurs in the weightlessness environment of space.

+ View Larger Image


image
NASA Image: ISS045E015466 - NASA astronaut Scott Kelly wearing a headset and a Chibis Lower Body Negative Pressure (LBNP) Suit, undergoes ultrasound measurements for the Fluid Shifts experiment.

+ View Larger Image


image NASA Image: ISS045E015549 - NASA astronaut Scott Kelly wearing a Chibis Lower Body Negative Pressure (LBNP) Suit, undergoes ultrasound measurements for the Fluid Shifts experiment.
+ View Larger Image


image NASA Image: JSC2015E046468 - Human Health Performance & Engineering, Biomedical Research & Environmental Sciences Cardio Lab.
+ View Larger Image


image
NASA Image: ISS045E015434 - Chibis Lower Body Negative Pressure (LBNP) Suit prior to its use in Fluid Shifts experiment operations. Image taken in the Zvezda Service Module (SM).

+ View Larger Image