This website could be intermittent Saturday Mar 30, 2024 starting 7PM until next day 11AM Eastern Time due to server/facility maintenance. We apologize for any inconvenience.

 

Menu

 

The NASA Task Book
Advanced Search     

Project Title:  Mobile Gravity Suit (an Integrative Countermeasure Device) Reduce
Images: icon  Fiscal Year: FY 2024 
Division: Human Research 
Research Discipline/Element:
HRP HHC:Human Health Countermeasures
Start Date: 10/04/2018  
End Date: 10/01/2023  
Task Last Updated: 01/21/2024 
Download report in PDF pdf
Principal Investigator/Affiliation:   Petersen, Lonnie  M.D., Ph.D. / University of California, San Diego 
Address:  Clinical Physiology Laboratory, Department of Orthopedic Surgery 
9452 Medical Center Dr, LL2 West 417 
La Jolla , CA 92037-1337 
Email: l8petersen@ucsd.edu 
Phone: 858-263-6365  
Congressional District: 52 
Web:  
Organization Type: UNIVERSITY 
Organization Name: University of California, San Diego 
Joint Agency:  
Comments:  
Co-Investigator(s)
Affiliation: 
Levine, Benjamin  M.D., Ph.D. University of Texas Southwestern Medical Center at Dallas 
Key Personnel Changes / Previous PI: Change (FY2021 report): Co-I Alan Hargens is no longer affiliated with this project.
Project Information: Grant/Contract No. 80NSSC19K0020 
Responsible Center: NASA JSC 
Grant Monitor: Stenger, Michael  
Center Contact: 281-483-1311 
michael.b.stenger@nasa.gov 
Unique ID: 12051 
Solicitation / Funding Source: 2017 HERO 80JSC017N0001-Crew Health and Performance (FLAGSHIP1, OMNIBUS). Appendix A-Flagship1, Appendix B-Omnibus 
Grant/Contract No.: 80NSSC19K0020 
Project Type: GROUND 
Flight Program:  
TechPort: Yes 
No. of Post Docs:
No. of PhD Candidates:
No. of Master's Candidates:
No. of Bachelor's Candidates: 40 
No. of PhD Degrees:  
No. of Master's Degrees:  
No. of Bachelor's Degrees: 20 
Human Research Program Elements: (1) HHC:Human Health Countermeasures
Human Research Program Risks: (1) SANS:Risk of Spaceflight Associated Neuro-ocular Syndrome (SANS)
Human Research Program Gaps: (1) SANS-301:Develop and test mechanical countermeasures in the laboratory.
Flight Assignment/Project Notes: NOTE: End date changed to 10/1/2023 per NSSC information (Ed., 4/3/23)

NOTE: End date changed to 10/1/2022 per NSSC information (Ed., 9/19/21)

NOTE: End date changed to 10/3/2021 per NSSC information (Ed., 8/21/20)

NOTE: End date changed to 10/3/2020 per NSSC information (Ed., 10/28/19)

Task Description: Because all parts of human physiology are affected by microgravity, an integrative countermeasure strategy is needed. Loss of muscle and bone mass along with deconditioning of the heart and vessels are well described effects of microgravity. More recently structural and functional changes of the eye, experienced by some astronauts during long-term missions, have been described and summarized in the Spaceflight Associated Neuro-ocular Syndrome (SANS). While the exact etiology of SANS remains unknown, the microgravity induced headward fluid shift is likely part of the pathophysiology and countermeasures that can reverse this fluid shift are prioritized.

Based on our experimental data from short-term microgravity by parabolic flights and 24-hour simulated microgravity, we suggest that fluid redistribution in space may not give rise to a pathological increase in intracranial pressure, but rather the lack of diurnal fluctuations in intracranial volume and pressures may be responsible for the remodeling of the eye. In ambulatory neurosurgical patients with pressure sensors inserted in the brain tissue, we therefore demonstrated the feasibility of lower body negative pressure to reduce intracranial pressure as means of re-introducing diurnal pressure variability. Extending on this, in a recent 3-day, 6° head-down tilt bedrest trial we applied lower body negative pressure (LBNP) for 8 hours every day, to demonstrate safety and efficacy to significantly reduce long-term swelling at the back of the eye believed to be early symptoms of SANS.

At the Aerospace Physiology Lab at University of California San Diego (UCSD) we have developed and tested a mobile "Gravity Suit" comprised of pressurized-trousers and attached vest. The suit simulates the effects of gravitational stress by application of low-levels lower body negative pressure to re-introduce an Earth-like fluid shift while at the same time inducing a ground reaction force at the bottom of the feet and a mechanical load along the entire body axis. Preliminary tests involving healthy human subjects in simulated microgravity have demonstrated the efficacy of 20 mmHg lower body negative pressure within the suit to reduce internal jugular vein cross-sectional area by some 45% and induce mechanical load of 57% bodyweight.

The intravehicular suit is comfortable enough to wear 8-10 hours a day and flexible enough to be combined with daily activity and even exercise with the overall aim to provide an integrative countermeasure. As an overall long-term aim, we suggest that use of the Gravity Suit will 1) re-introduce the diurnal variability of intracranial pressure and volume to help prevent development of SANS; 2) stimulate the cardiovascular system to maintain cardiac muscle mass and vascular compliance; 3) counteract loss of postural muscle mass and bone density; 4) finally, the axial loading may preserve curvature of the spine, paraspinal muscle, and disc morphology to both ameliorate in-flight back pain, and reduce risk of post-flight disc herniation.

Within the scope of this proposal, we will finalize and further test our prototype by integrating vacuum- and monitoring systems within the waist-belt to increase safety and allow for free and un-tethered movement. Comfort, range of motion, and gait will be assessed during relevant activities simulating daily work tasks on the International Space Station (ISS) and in combination with resistive exercise device relevant for cislunar and deep space missions. High levels and/or prolonged exposure to lower body negative pressure can potentially compromise blood flow to the brain; however, activity and use of the muscle pump increases orthostatic tolerance. To establish a safe range and optimize the user scenario, we will test cardiovascular responses and cerebral perfusion during graded lower body negative pressure with and without a combined ground reaction force and in combination with rowing exercise. Successful funding of this proposal will bring our Gravity Suit to Countermeasure Readiness Level 7.

Research Impact/Earth Benefits: While designed as a countermeasure for use in space, LBNP may hold benefits for life on Earth. One specific example is reduction of pressure inside the brain which may hold potential for patients on Earth with elevated intracranial pressure.

Task Progress & Bibliography Information FY2024 
Task Progress: The project met all outlined aims and included significant technology development and validation in human subjects. Main deliverable is a functional, wearable and mobile LBNP-suit (GravitySuit) which is comfortable enough to wear for several hours of use and compatible with most everyday activities.

Bibliography: Description: (Last Updated: 01/24/2024) 

Show Cumulative Bibliography
 
Articles in Peer-reviewed Journals Petersen L. "Arterial and intracranial hypotension during and following exercise." Physiology. 2023 May;38(S1):5793685. https://doi.org/10.1152/physiol.2023.38.S1.5793685 , May-2023
Articles in Peer-reviewed Journals Harris KM, Arya R, Elias A, Weber T, Green DA, Greaves DK, Petersen LG, Roberts L, Kamine TH, Mazzolai L, Bergauer A, Kim DS, Olde Engberink RH, Zu Eulenberg P, Grassi B, Zuccarelli L, Baldassarre G, Tabury K, Baatout S, Jordan J, Blaber AP, Choukér A, Russomano T, Goswami N. "Pathophysiology, risk, diagnosis, and management of venous thrombosis in space: Where are we now?" npj Microgravity. 2023 Feb 16;9:17. Review. https://doi.org/10.1038/s41526-023-00260-9 ; PMID: 36797288; PMCID: PMC9935502 , Feb-2023
Articles in Peer-reviewed Journals Harris K, Laws JM, Elias DA, Green A, Goswami N, Jordan J, Kamine TH, Mazzolai L, Petersen LG, Winnard AJ, Weber T. "Search for venous endothelial biomarkers heralding venous thromboembolism in space: A qualitative systematic review of terrestrial studies." Front Physiol. 2022 Apr 27;13:885183. https://doi.org/10.3389/fphys.2022.885183 ; PMID: 35574486; PMCID: PMC9092216 , Apr-2022
Articles in Peer-reviewed Journals Petersen LG, Whittle RS, Lee JH, Sieker J, Carlson J, Finke C, Shelton CM, Petersen JCG, Diaz-Artiles A. "Gravitational effects on ocular pressure and perfusion pressure." J Appl Physiol (1985). 2022 Jan 1;132(1):24-35. https://doi.org/10.1152/japplphysiol.00546.2021 ; PMID: 34762525 , Jan-2022
Articles in Peer-reviewed Journals Whittle RS, Stapleton LM, Petersen LG, Diaz-Artiles A. "Indirect measurement of absolute cardiac output during exercise in simulated altered gravity is highly dependent on the method." J Clin Monit Comput. 2022 Oct;36(5):1355-66. https://doi.org/10.1007/s10877-021-00769-y ; PMID: 34677821 , Oct-2022
Project Title:  Mobile Gravity Suit (an Integrative Countermeasure Device) Reduce
Images: icon  Fiscal Year: FY 2022 
Division: Human Research 
Research Discipline/Element:
HRP HHC:Human Health Countermeasures
Start Date: 10/04/2018  
End Date: 10/01/2023  
Task Last Updated: 11/09/2023 
Download report in PDF pdf
Principal Investigator/Affiliation:   Petersen, Lonnie  M.D., Ph.D. / University of California, San Diego 
Address:  Clinical Physiology Laboratory, Department of Orthopedic Surgery 
9452 Medical Center Dr, LL2 West 417 
La Jolla , CA 92037-1337 
Email: l8petersen@ucsd.edu 
Phone: 858-263-6365  
Congressional District: 52 
Web:  
Organization Type: UNIVERSITY 
Organization Name: University of California, San Diego 
Joint Agency:  
Comments:  
Co-Investigator(s)
Affiliation: 
Levine, Benjamin  M.D., Ph.D. University of Texas Southwestern Medical Center at Dallas 
Key Personnel Changes / Previous PI: Change (FY2021 report): Co-I Alan Hargens is no longer affiliated with this project.
Project Information: Grant/Contract No. 80NSSC19K0020 
Responsible Center: NASA JSC 
Grant Monitor: Stenger, Michael  
Center Contact: 281-483-1311 
michael.b.stenger@nasa.gov 
Unique ID: 12051 
Solicitation / Funding Source: 2017 HERO 80JSC017N0001-Crew Health and Performance (FLAGSHIP1, OMNIBUS). Appendix A-Flagship1, Appendix B-Omnibus 
Grant/Contract No.: 80NSSC19K0020 
Project Type: GROUND 
Flight Program:  
TechPort: Yes 
No. of Post Docs:
No. of PhD Candidates:
No. of Master's Candidates:
No. of Bachelor's Candidates: 40 
No. of PhD Degrees:  
No. of Master's Degrees:  
No. of Bachelor's Degrees: 20 
Human Research Program Elements: (1) HHC:Human Health Countermeasures
Human Research Program Risks: (1) SANS:Risk of Spaceflight Associated Neuro-ocular Syndrome (SANS)
Human Research Program Gaps: (1) SANS-301:Develop and test mechanical countermeasures in the laboratory.
Flight Assignment/Project Notes: NOTE: End date changed to 10/1/2023 per NSSC information (Ed., 4/3/23)

NOTE: End date changed to 10/1/2022 per NSSC information (Ed., 9/19/21)

NOTE: End date changed to 10/3/2021 per NSSC information (Ed., 8/21/20)

NOTE: End date changed to 10/3/2020 per NSSC information (Ed., 10/28/19)

Task Description: Because all parts of human physiology are affected by microgravity, an integrative countermeasure strategy is needed. Loss of muscle and bone mass along with deconditioning of the heart and vessels are well described effects of microgravity. More recently structural and functional changes of the eye, experienced by some astronauts during long-term missions, have been described and summarized in the Spaceflight Associated Neuro-ocular Syndrome (SANS). While the exact etiology of SANS remains unknown, the microgravity induced headward fluid shift is likely part of the pathophysiology and countermeasures that can reverse this fluid shift are prioritized.

Based on our experimental data from short-term microgravity by parabolic flights and 24-hour simulated microgravity, we suggest that fluid redistribution in space may not give rise to a pathological increase in intracranial pressure, but rather the lack of diurnal fluctuations in intracranial volume and pressures may be responsible for the remodeling of the eye. In ambulatory neurosurgical patients with pressure sensors inserted in the brain tissue, we therefore demonstrated the feasibility of lower body negative pressure to reduce intracranial pressure as means of re-introducing diurnal pressure variability. Extending on this, in a recent 3-day, 6° head-down tilt bedrest trial we applied lower body negative pressure (LBNP) for 8 hours every day, to demonstrate safety and efficacy to significantly reduce long-term swelling at the back of the eye believed to be early symptoms of SANS.

At the Aerospace Physiology Lab at University of California San Diego (UCSD) we have developed and tested a mobile "Gravity Suit" comprised of pressurized-trousers and attached vest. The suit simulates the effects of gravitational stress by application of low-levels lower body negative pressure to re-introduce an Earth-like fluid shift while at the same time inducing a ground reaction force at the bottom of the feet and a mechanical load along the entire body axis. Preliminary tests involving healthy human subjects in simulated microgravity have demonstrated the efficacy of 20 mmHg lower body negative pressure within the suit to reduce internal jugular vein cross-sectional area by some 45% and induce mechanical load of 57% bodyweight.

The intravehicular suit is comfortable enough to wear 8-10 hours a day and flexible enough to be combined with daily activity and even exercise with the overall aim to provide an integrative countermeasure. As an overall long-term aim, we suggest that use of the Gravity Suit will 1) re-introduce the diurnal variability of intracranial pressure and volume to help prevent development of SANS; 2) stimulate the cardiovascular system to maintain cardiac muscle mass and vascular compliance; 3) counteract loss of postural muscle mass and bone density; 4) finally, the axial loading may preserve curvature of the spine, paraspinal muscle, and disc morphology to both ameliorate in-flight back pain, and reduce risk of post-flight disc herniation.

Within the scope of this proposal, we will finalize and further test our prototype by integrating vacuum- and monitoring systems within the waist-belt to increase safety and allow for free and un-tethered movement. Comfort, range of motion, and gait will be assessed during relevant activities simulating daily work tasks on the International Space Station (ISS) and in combination with resistive exercise device relevant for cislunar and deep space missions. High levels and/or prolonged exposure to lower body negative pressure can potentially compromise blood flow to the brain; however, activity and use of the muscle pump increases orthostatic tolerance. To establish a safe range and optimize the user scenario, we will test cardiovascular responses and cerebral perfusion during graded lower body negative pressure with and without a combined ground reaction force and in combination with rowing exercise. Successful funding of this proposal will bring our Gravity Suit to Countermeasure Readiness Level 7.

Research Impact/Earth Benefits: While designed as a countermeasure for use in space, LBNP may hold benefits for life on Earth. One specific example is reduction of pressure inside the brain which may hold potential for patients on Earth with elevated intracranial pressure.

Task Progress & Bibliography Information FY2022 
Task Progress: Ed. Note -- May 2023 Update Compiled from January 2023 report to NASA

2022/23 UPDATE -- COVID IMPACT:

University of California, San Diego (UCSD) closed down early in 2020 and regrettably did not fully open for human-subject testing until 2022 (only COVID-related research could be done). The Aerospace Physiology lab (Petersen lab) submitted, and was approved for, onsite research ramp-up; however, all work has been under significant restrictions and 6 feet distance has to be maintained at all times. Thus, research with human subjects has been close to impossible. Based on this, I was granted a no-cost extension on this grant.

Because no human subject research was possible for a significant period, I focused efforts on work that was possible; therefore significant technical / engineering advances have been made.

Based on feedback from NASA's Human Research Program (HRP), it is important to move away from a lithium battery-based system. However, this poses a challenge for weight, size, and lifetime of the alternative batteries. My team and I have tested multiple vacuum systems and customized functionality to be specifically tailored towards a wearable lower body negative pressure (LBNP) device. Additionally, much experimental work has gone into material selection. Based on this, my recommendation is a two-layer softshell with the inner lining being a soft material with optimized wicking capacity and an outer layer of more robust and airtight material.

Mobility across the individual joint has also been a focus and we have created a knee design that allows for full mobility without contact with the skin. We are currently evaluating materials for the structural support of the knee joint.

Bibliography: Description: (Last Updated: 01/24/2024) 

Show Cumulative Bibliography
 
 None in FY 2022
Project Title:  Mobile Gravity Suit (an Integrative Countermeasure Device) Reduce
Images: icon  Fiscal Year: FY 2021 
Division: Human Research 
Research Discipline/Element:
HRP HHC:Human Health Countermeasures
Start Date: 10/04/2018  
End Date: 10/01/2022  
Task Last Updated: 05/05/2021 
Download report in PDF pdf
Principal Investigator/Affiliation:   Petersen, Lonnie  M.D., Ph.D. / University of California, San Diego 
Address:  Clinical Physiology Laboratory, Department of Orthopedic Surgery 
9452 Medical Center Dr, LL2 West 417 
La Jolla , CA 92037-1337 
Email: l8petersen@ucsd.edu 
Phone: 858-263-6365  
Congressional District: 52 
Web:  
Organization Type: UNIVERSITY 
Organization Name: University of California, San Diego 
Joint Agency:  
Comments:  
Co-Investigator(s)
Affiliation: 
Levine, Benjamin  M.D., Ph.D. University of Texas Southwestern Medical Center at Dallas 
Key Personnel Changes / Previous PI: Change (FY2021 report): Co-I Alan Hargens is no longer affiliated with this project.
Project Information: Grant/Contract No. 80NSSC19K0020 
Responsible Center: NASA JSC 
Grant Monitor: Stenger, Michael  
Center Contact: 281-483-1311 
michael.b.stenger@nasa.gov 
Unique ID: 12051 
Solicitation / Funding Source: 2017 HERO 80JSC017N0001-Crew Health and Performance (FLAGSHIP1, OMNIBUS). Appendix A-Flagship1, Appendix B-Omnibus 
Grant/Contract No.: 80NSSC19K0020 
Project Type: GROUND 
Flight Program:  
TechPort: Yes 
No. of Post Docs:
No. of PhD Candidates:
No. of Master's Candidates:
No. of Bachelor's Candidates: 20 
No. of PhD Degrees:  
No. of Master's Degrees:  
No. of Bachelor's Degrees:  
Human Research Program Elements: (1) HHC:Human Health Countermeasures
Human Research Program Risks: (1) SANS:Risk of Spaceflight Associated Neuro-ocular Syndrome (SANS)
Human Research Program Gaps: (1) SANS-301:Develop and test mechanical countermeasures in the laboratory.
Flight Assignment/Project Notes: NOTE: End date changed to 10/1/2022 per NSSC information (Ed., 9/19/21)

NOTE: End date changed to 10/3/2021 per NSSC information (Ed., 8/21/20)

NOTE: End date changed to 10/3/2020 per NSSC information (Ed., 10/28/19)

Task Description: Because all parts of human physiology are affected by microgravity, an integrative countermeasure strategy is needed. Loss of muscle and bone mass along with deconditioning of the heart and vessels are well described effects of microgravity. More recently structural and functional changes of the eye, experienced by some astronauts during long-term missions, have been described and summarized in the Spaceflight Associated Neuro-ocular Syndrome (SANS). While the exact etiology of SANS remains unknown, the microgravity induced headward fluid shift is likely part of the pathophysiology and countermeasures that can reverse this fluid shift are prioritized.

Based on our experimental data from short-term microgravity by parabolic flights and 24-hour simulated microgravity, we suggest that fluid redistribution in space may not give rise to a pathological increase in intracranial pressure, but rather the lack of diurnal fluctuations in intracranial volume and pressures may be responsible for the remodeling of the eye. In ambulatory neurosurgical patients with pressure sensors inserted in the brain tissue, we therefore demonstrated the feasibility of lower body negative pressure to reduce intracranial pressure as means of re-introducing diurnal pressure variability. Extending on this, in a recent 3-day, 6° head-down tilt bedrest trial we applied lower body negative pressure (LBNP) for 8 hours every day, to demonstrate safety and efficacy to significantly reduce long-term swelling at the back of the eye believed to be early symptoms of SANS.

At the Aerospace Physiology Lab at University of California San Diego (UCSD) we have developed and tested a mobile "Gravity Suit" comprised of pressurized-trousers and attached vest. The suit simulates the effects of gravitational stress by application of low-levels lower body negative pressure to re-introduce an Earth-like fluid shift while at the same time inducing a ground reaction force at the bottom of the feet and a mechanical load along the entire body axis. Preliminary tests involving healthy human subjects in simulated microgravity have demonstrated the efficacy of 20 mmHg lower body negative pressure within the suit to reduce internal jugular vein cross-sectional area by some 45% and induce mechanical load of 57% bodyweight.

The intravehicular suit is comfortable enough to wear 8-10 hours a day and flexible enough to be combined with daily activity and even exercise with the overall aim to provide an integrative countermeasure. As an overall long-term aim, we suggest that use of the Gravity Suit will 1) re-introduce the diurnal variability of intracranial pressure and volume to help prevent development of SANS; 2) stimulate the cardiovascular system to maintain cardiac muscle mass and vascular compliance; 3) counteract loss of postural muscle mass and bone density; 4) finally, the axial loading may preserve curvature of the spine, paraspinal muscle, and disc morphology to both ameliorate in-flight back pain, and reduce risk of post-flight disc herniation.

Within the scope of this proposal, we will finalize and further test our prototype by integrating vacuum- and monitoring systems within the waist-belt to increase safety and allow for free and un-tethered movement. Comfort, range of motion, and gait will be assessed during relevant activities simulating daily work tasks on the International Space Station (ISS) and in combination with resistive exercise device relevant for cislunar and deep space missions. High levels and/or prolonged exposure to lower body negative pressure can potentially compromise blood flow to the brain; however, activity and use of the muscle pump increases orthostatic tolerance. To establish a safe range and optimize the user scenario, we will test cardiovascular responses and cerebral perfusion during graded lower body negative pressure with and without a combined ground reaction force and in combination with rowing exercise. Successful funding of this proposal will bring our Gravity Suit to Countermeasure Readiness Level 7.

Research Impact/Earth Benefits: While designed as a countermeasure for use in space, LBNP may hold benefits for life on Earth. One specific example is reduction of pressure inside the brain which may hold potential for patients on Earth with elevated intracranial pressure.

Task Progress & Bibliography Information FY2021 
Task Progress: Ongoing Work and Scope of Second Year of Funding

The focus of ongoing work is to further investigate any potential physiological differences in response between classic LBNP and LBNP including ground reaction forces (GRF). The bulk of available literature includes “classic” LBNP (no GRF) which seems promising as a countermeasure for SANS (Lawley et al. Daily Generation of a Footward Fluid Shift Attenuates Ocular Changes Associated with Head-Down Tilt Bedrest. J Appl Physiol. 129(5), 1220-1231, 2020). With the second year of the omnibus project, I aim to further investigate potential differences in LBNP response when GRF are allowed. Since GRF include activation of the muscle pump and a potentially a myriad of other reflexes from proprioceptor and vestibular-cardio reflexes, it is possible that the cardiovascular response to LBNP+GRF is modulated. Furthermore, we will continue the development of the GravitySuit, particularly focusing on the vacuum and safety systems.

COVID UPDATE: UCSD closed down early in 2020 and has, regrettably, not fully opened up yet. Aerospace Physiology lab (Petersen lab) submitted and was approved for on-site research ramp-up; however, all work has been under significant restrictions and 6 feet distance has to be maintained at all times. Thus, research with human subjects has been close to impossible and I have focused efforts that were possible; therefore, significant technical advances have been made while some experimental data was collected.

Technical Progress: Based on feedback from HRP (NASA's Human Research Program), we have updated the battery system and vacuum system. Additionally, much experimental work has gone into material selection both for the soft-shell and the structure framework. Mobility across the individual joint has also been a focus and we have created a knee design that allows for full mobility without contact with the skin. We are currently evaluating materials for the structural support of the knee joint.

Experimental procedure arm: I was able to include nine subjects in the experimental arm of the extension grant. Please find abstract summarizing method and data below:

Title: LOWER BODY NEGATIVE PRESSURE AS INTEGRATIVE COUNTERMEASURE DURING SPACEFLIGHT

INTRODUCTION: Because most aspects of human physiology are affected by microgravity, an integrated countermeasure strategy is warranted. Deconditioning of the cardiovascular and musculoskeletal system are well described consequences of long-tern spaceflight and more recently the Spaceflight-Associated Neuro-ocular Syndrome (SANS) has been identified and classified as a major risk factor. While exact mechanisms are incompletely understood, combined effects of altered fluid distribution and lack of diurnal intracranial pressure (ICP) variability are likely key factors. Lower body negative pressure (LBNP) simulates the beneficial effects of gravity by re-introducing foot-ward fluid shift and generating mechanical loading. In ground-based trials we have demonstrated the dose-response relationship between LBNP and ICP and determined 20-30 mmHg as recommended level counteract cephalic congestion without impairing cerebral perfusion (Petersen et al. 2018) and when applied for 8-hours daily during slight head-down tilt bedrest LBNP ameliorated choroidal engorgement and other early signs of SANS (Lawley et al. 2020). AIM: To increase feasibility of LBNP during spaceflight we have developed and validated a wearable, flexible, and mobile LBNP: GravitySuit (Petersen et al. 2019). Application of LBNP in a weightless environment differs from that of ground-based in that the subject cannot rely on friction forces (1GX) to prevent them from being displaced into the device. Therefore, subject must push off against the bottom of the device and LBNP-induced ground-reaction forces (GRF) between subjects’ feet and device are inevitable. This project investigated if LBNP with and without GRF induce similar physiological responses.

METHOD AND RESULTS: Nine healthy young volunteers (5/4 female/male) were included in a randomized cross-over trial and incremental LBNP from 0 to 40 mmHg was applied for 2 min either with use of a foot-board for subjects to push off against (+GRF) or with use of a saddle to prevent any mechanical forces (-GRF). Cardiovascular parameters (Nexfin) and internal jugular venous cross-sectional area (IJVa) were recorded.

We found no statistical difference in blood pressure responses, cardiac stroke volume or cardiac output between +GFR and -GFR at any level of LBNP. Importantly, IJVa was reduced to the same extend by incremental LBNP with and without GRF: from a baseline of 1.1 +/- 0.4 cm2 to 0.4 +/- 3.3 cm2 at 40mmHg without GRF; and from 1.1 +/- 0.6 cm2 to 0.4 +/- 0.3 cm2 with GRF (mean +/- SD; P>0.05). The increase in heart rate at every level of LBNP was trended to be smaller when GRF were allowed compared to no GRF but failed to reach statistical significance.

DISCUSSION: Volumetric values responded in a similar fashion during short term application of LBNP with and without GRF. Heart rate trended toward a blunted LBNP-induced increase when GRF were included. LBNP +GRF more closely simulates a normal upright standing posture, which usually does not induce syncope to the same extend as passive head-up tilt or LBNP without GRF. GRF introduces a host of compensatory mechanisms including the muscle venous pump and orthostatic cardiovascular reflexes. Potential differences in effect during long-term LBNP application remain unknown. We recommend future ground-based analogue trials investigating LBNP as a countermeasure considers not only duration of application but also the method including +/- GRF. The mandatory GRF when LBNP is applied in weightlessness is a limitation for considerations of applying LBNP during sleep.

References

Petersen LG, Lawley JS, Lilja-Cyron A, Petersen JCG, Howden EJ, Sarma S, Cornwell WK, Zhang R, Whitworth LA, Williams MA, Juhler M, Levine BD. Lower Body Negative Pressure to Safely Reduce Intracranial Pressure. J Phys 597:237-248, 2018

Lawley JS, Babu G, Janssen SLJE, Petersen LG, Hearon Jr. CM, Dias KA, Sarma S, Williams MA, Whitworth LA, Levine BD. Daily Generation of a Footward Fluid Shift Attenuates Ocular Changes Associated with Head-Down Tilt Bedrest. J Appl Physiol. 129(5), 1220-1231, 2020

Petersen LG, Hargens A, Bird E, Ashari N, Saalfeld J, Petersen JCG. Mobile Lower Body Negative Pressure Suit as an Integrative Countermeasure for Spaceflight. Aerospace Medicine and Human Performance. 1;90(12):993-999, 2019

Bibliography: Description: (Last Updated: 01/24/2024) 

Show Cumulative Bibliography
 
Articles in Peer-reviewed Journals Harris KM, Petersen LG, Weber T. "Reviving lower body negative pressure as a countermeasure to prevent pathological vascular and ocular changes in microgravity." npj Microgravity. 2020 Dec 17;6(1):38. https://doi.org/10.1038/s41526-020-00127-3 ; PMID: 33335101; PMCID: PMC7746725 , Dec-2020
Articles in Peer-reviewed Journals Ogoh S, Washio T, Paton JFR, Fisher JP, Petersen LG. "Gravitational effects on intracranial pressure and blood flow regulation in young men: a potential shunting role for the external carotid artery." J Appl Physiol (1985). 2020 Oct 1;129(4):901-8. Epub 2020 Aug 20. https://doi.org/10.1152/japplphysiol.00369.2020 ; PMID: 32816640 , Oct-2020
Articles in Peer-reviewed Journals Roberts DR, Petersen LG. "Studies of hydrocephalus associated with long-term spaceflight may provide new insights into cerebrospinal fluid flow dynamics here on Earth. [Editorial comment on Lee et al. Spaceflight-associated brain white matter microstructural changes and intracranial fluid redistribution. JAMA Neurol. 2019 Apr 1;76(4):412-9. https://doi.org/10.1001/jamaneurol.2018.4882 ]" JAMA Neurology. 2019 Apr;76(4):391-2. https://doi.org/10.1001/jamaneurol.2018.4891 ; PubMed PMID: 30673794 , Apr-2019
Papers from Meeting Proceedings Harris K, Petersen LG, Damann V, Scott J, Weber T. "Effects of Lower-body Negative Pressure on Fluid Distribution During Gravitational Unloading." 70th International Astronautical Congress (IAC), Washington, DC, October 21-25, 2019.

70th International Astronautical Congress (IAC), Washington, DC, October 21-25, 2019. Paper IAC-19,A1,4,1149136. , Oct-2019

Project Title:  Mobile Gravity Suit (an Integrative Countermeasure Device) Reduce
Images: icon  Fiscal Year: FY 2020 
Division: Human Research 
Research Discipline/Element:
HRP HHC:Human Health Countermeasures
Start Date: 10/04/2018  
End Date: 10/03/2020  
Task Last Updated: 11/07/2019 
Download report in PDF pdf
Principal Investigator/Affiliation:   Petersen, Lonnie  M.D., Ph.D. / University of California, San Diego 
Address:  Clinical Physiology Laboratory, Department of Orthopedic Surgery 
9452 Medical Center Dr, LL2 West 417 
La Jolla , CA 92037-1337 
Email: l8petersen@ucsd.edu 
Phone: 858-263-6365  
Congressional District: 52 
Web:  
Organization Type: UNIVERSITY 
Organization Name: University of California, San Diego 
Joint Agency:  
Comments:  
Co-Investigator(s)
Affiliation: 
Hargens, Alan  Ph.D. University of California, San Diego 
Levine, Benjamin  M.D., Ph.D. University of Texas Southwestern Medical Center at Dallas 
Project Information: Grant/Contract No. 80NSSC19K0020 
Responsible Center: NASA JSC 
Grant Monitor: Norsk, Peter  
Center Contact:  
Peter.norsk@nasa.gov 
Unique ID: 12051 
Solicitation / Funding Source: 2017 HERO 80JSC017N0001-Crew Health and Performance (FLAGSHIP1, OMNIBUS). Appendix A-Flagship1, Appendix B-Omnibus 
Grant/Contract No.: 80NSSC19K0020 
Project Type: GROUND 
Flight Program:  
TechPort: Yes 
No. of Post Docs:
No. of PhD Candidates:
No. of Master's Candidates:
No. of Bachelor's Candidates:
No. of PhD Degrees:  
No. of Master's Degrees:  
No. of Bachelor's Degrees:  
Human Research Program Elements: (1) HHC:Human Health Countermeasures
Human Research Program Risks: (1) SANS:Risk of Spaceflight Associated Neuro-ocular Syndrome (SANS)
Human Research Program Gaps: (1) SANS-301:Develop and test mechanical countermeasures in the laboratory.
Flight Assignment/Project Notes: NOTE: End date changed to 10/3/2020 per NSSC information (Ed., 10/28/19)

Task Description: Because all parts of human physiology are affected by microgravity, an integrative countermeasure strategy is needed. Loss of muscle and bone mass along with deconditioning of the heart and vessels are well described effects of microgravity. More recently structural and functional changes of the eye, experienced by some astronauts during long-term missions, have been described and summarized in the Spaceflight Associated Neuro-ocular Syndrome (SANS). While the exact etiology of SANS remains unknown, the microgravity induced headward fluid shift is likely part of the pathophysiology and countermeasures that can reverse this fluid shift are prioritized.

Based on our experimental data from short-term microgravity by parabolic flights and 24-hour simulated microgravity, we suggest that fluid redistribution in space may not give rise to a pathological increase in intracranial pressure, but rather the lack of diurnal fluctuations in intracranial volume and pressures may be responsible for the remodeling of the eye. In ambulatory neurosurgical patients with pressure sensors inserted in the brain tissue, we therefore demonstrated the feasibility of lower body negative pressure to reduce intracranial pressure as means of re-introducing diurnal pressure variability. Extending on this, in a recent 3-day, 6° head-down tilt bedrest trial we applied lower body negative pressure (LBNP) for 8 hours every day, to demonstrate safety and efficacy to significantly reduce long-term swelling at the back of the eye believed to be early symptoms of SANS.

At the University of California San Diego we have developed and tested a fully mobile "Gravity Suit" comprised of pressurized-trousers and attached vest. The suit simulates the effects of gravitational stress by application of low-levels lower body negative pressure to re-introduce an Earth-like fluid shift while at the same time inducing a ground reaction force at the bottom of the feet and a mechanical load along the entire body axis. Preliminary tests involving healthy human subjects in simulated microgravity have demonstrated the efficacy of 20 mmHg lower body negative pressure within the suit to reduce internal jugular vein cross-sectional area by some 45% and induce mechanical load of 57% bodyweight.

The intravehicular suit is comfortable enough to wear 8-10 hours a day and flexible enough to be combined with daily activity and even exercise with the overall aim to provide an integrative countermeasure. As an overall long-term aim, we suggest that use of the Gravity Suit will 1) re-introduce the diurnal variability of intracranial pressure and volume to help prevent development of SANS; 2) stimulate the cardiovascular system to maintain cardiac muscle mass and vascular compliance; 3) counteract loss of postural muscle mass and bone density; 4) finally, the axial loading will preserve curvature of the spine, paraspinal muscle, and disc morphology to both ameliorate in-flight back pain, and reduce risk of post-flight disc herniation.

Within the scope of this proposal, we will finalize and further test our prototype by integrating vacuum- and monitoring systems within the waist-belt to increase safety and allow for free and un-tethered movement. Comfort, range of motion, and gait will be assessed during relevant activities simulating daily work tasks on the International Space Station (ISS) and in combination with resistive exercise device relevant for cislunar and deep space missions. High levels and/or prolonged exposure to lower body negative pressure can potentially compromise blood flow to the brain; however, activity and use of the muscle pump increases orthostatic tolerance. To establish a safe range and optimize the user scenario, we will test cardiovascular responses and cerebral perfusion during graded lower body negative pressure with and without a combined ground reaction force and in combination with rowing exercise. Successful funding of this proposal will bring our Gravity Suit to Countermeasure Readiness Level 7.

Research Impact/Earth Benefits: While designed as a countermeasure for use in space, LBNP may hold benefits for life on Earth. One specific example is reduction of pressure inside the brain which may hold potential for patients on Earth with elevated intracranial pressure.

Task Progress & Bibliography Information FY2020 
Task Progress: Introduction: Because all aspects of human physiology are affected by microgravity, an integrated countermeasure approach is warranted. The aim of this proposal is to finalize and further validate our prototype of an intravehicular mobile countermeasure suit, which consists of lower body negative pressure (LBNP) trousers and vest to reproduce the effects of gravitational stress during spaceflight. This mobile “Gravity Suit” aims to be: 1) Comfortable enough to allow for use for several hours per day, which entails monitoring and some form of regulation of the internal environment (temperature and humidity); 2) Not interfere with everyday in-flight activities, which entails being slim enough to allow for movement around the station and to be mobile and un-tethered, i.e., to have a mobile battery-operated vacuum system; 3) be flexible enough to be combined with some forms of exercise and movement, which entails ability to flex the knee and hip to at least 90 degrees.

Background: LBNP was used as early as the Apollo program through Skylab and Mir (Hoffler et al. 1977, Iwasaki et al. 2007). Currently the Russian LBNP device (“Chibis”) is available on International Space Station (ISS). Several indications point to beneficial multi-system effects. To make LBNP feasible as a countermeasure, we created a wearable, untethered, mobile, and flexible device.

Aim: To test that the suit induces caudal fluid shift as know from “classic rigid LBNP” devices (Petersen et al. 2019) and in addition to that it provides mechanical loading of the body which could potentially be beneficial for the musculoskeletal system.

Materials and Methods: We have designed and built a wearable LBNP device consisting of a set of trousers that can be pressurized with a seal created at the iliac crest and attached “boots” that support ground reaction forces. The mechanical loads are carried to the shoulders by means of the attached vest to provide mechanical loading to the entire axial length of the body. Negative pressure is generated by a portable vacuum powered by a rechargeable battery. Following Institutional Review Board (IRB) approval 8 healthy subjects were included in initial testing. Mechanical loading was quantified as ground reaction forces (GRF) under the sole of each foot using force sensors (Tekscan, USA) and on the shoulders under the vest. Caudal fluid shift was assessed from the reductions in internal jugular venous cross-sectional area (IJVa) using ultrasounds (treason t3200, treason, USA). Continuous cardiovascular profile was recorded using the volume-clamp method from a finger cuff (Nexfin, BMeye, The Netherlands) and presented as 1 min average following 5 minutes of rest at each condition. Range of motion was recorded as maximum comfortable angle of flexion of the hip and knees from the normal position. Incremental LBNP from 0 to 40 mmHg at increments of 10 mmHg were applied while subjects were resting in a suspended supine position. Following completion of the incremental protocol, LBNP was set at 20 mmHg and range of motion at this level was recorded.

Results: Relative to normal body weight (BW) when standing upright, increments of 10 mmHg LBNP from 0 to 40 mmHg whilst supine generated incremental axial mechanical loading of the body with around 35 mmHg generating close to one bodyweight. Caudal fluid displacement was indicated by the significant reduction of IVJa while cardiovascular parameters were well maintained (P > 0.05) with the exception of stroke volume (SV) which decreased at 40 mmHg, and which was accompanied by a non-significant increase in heart rate (HR). Mean arterial blood pressure (MAP) was maintained throughout the incremental LBNP protocol. Range of motion across the hip and knee joints was measured and confirmed to reach 90 degrees.

Discussion: LBNP is a potential countermeasure to reverse the cranial fluid shift associated with weightlessness. In the first year of this omnibus project, we have demonstrated that a caudal fluid shift and mechanical loading can be achieved using a wearable mobile LBNP suit.

Limitations: An important limitation is the restricted dimensions of the suit which only allowed for inclusion of subjects with a limited waist-, hip-, and leg-circumference and length of the legs. Ongoing efforts are directed toward including subjects of varying size and further investigating the effects of LBNP in combination with GRF.

References

Hoffler WG, Johnson P, Nicogossian AE, et al Vectorcardiographic Results From Skylab Medical Experiment M092: Lower Body Negative Presure. In: Biomedical results from Skylab. Scientific and Technical Information Office, National Aeronautics and Space Administration, Washington, D.C., pp 313–323, 1977

Iwasaki K,Levine BD, Zhang R, Zuckerman JH, Pawelczyk JA, Diedrich A, Ertl AC, Cox JF, Cooke WH, Giller CA, Ray CA, Lane LD, Buckey JC Jr, Baisch FJ, Eckberg DL, Robertson D, Biaggioni I, Blomqvist CG. Human cerebral autoregulation before, during and after spaceflight J Physiol. 579:799-810. 2007

Petersen LG, Lawley JS, Lilja-Cyron A, Petersen JCG, Howden EJ, Sarma S, Cornwell WK, Zhang R, Whitworth LA, Williams MA, Juhler M, Levine BD. Lower Body Negative Pressure To Safely Reduce Intracranial Pressure. J Phys 597:237-248, 2019.

Bibliography: Description: (Last Updated: 01/24/2024) 

Show Cumulative Bibliography
 
Abstracts for Journals and Proceedings Petersen LG. "Effects of Gravity and Spaceflight on Fluid Shifts and Neuro-ocular Impairment: Countermeasures." Presented at 39th International Society for Gravitational Physiology (ISGP) & European Space Agency (ESA) Life Sciences Meeting, Noordwijk, Netherlands, June 18-22, 2018.

Abstracts. 39th International Society for Gravitational Physiology (ISGP) & European Space Agency (ESA) Life Sciences Meeting, Noordwijk, Netherlands, June 18-22, 2018. , Jun-2018

Abstracts for Journals and Proceedings Petersen LG, Hargens A, Levine B. "Mobile Negative Pressure Suit as an Integrative Countermeasure." Poster, 2019 NASA Human Research Program Investigators’ Workshop, Galveston, TX, January 22-25, 2019.

Abstracts. 2019 NASA Human Research Program Investigators’ Workshop, Galveston, TX, January 22-25, 2019. , Jan-2019

Abstracts for Journals and Proceedings Petersen LG. "Mobile Lower Body Negative Pressure Suit as an Integrative Countermeasure." Presented at 90th Aerospace Medicine Association Meeting, Las Vegas, NV, May 5-19, 2019.

Aerospace Medicine and Human Performance. 2019 Mar;90(3). , Mar-2019

Articles in Peer-reviewed Journals Petersen LG, Ogoh S. "Gravity, intracranial pressure, and cerebral autoregulation." Physiol Rep. 2019 Mar;7(6):e14039. https://doi.org/10.14814/phy2.14039 ; PubMed PMID: 30912269; PubMed Central PMCID: PMC6434070 , Mar-2019
Articles in Peer-reviewed Journals Petersen LG, Hargens A, Bird EM, Ashari N, Saalfeld J, Petersen JCG. "Mobile lower body negative pressure suit as an integrative countermeasure for spaceflight." Aerosp Med Hum Perform. 2019 Dec 1;90(12):993-9. https://doi.org/10.3357/AMHP.5408.2019 ; Pubmed PMID: 31747995 [note reported previously in November 2019 as 'Aerospace Medicine and Human Performance, accepted for publication as of October 2019.'] , Dec-2019
Awards Petersen LG. "1st Place Aerospace Medical and Human Performance, AMSRO Scientific Paper Award. 89th Aerospace Medicine Association Meeting, Las Vegas, NV, May 5-19, 2019." May-2019
Project Title:  Mobile Gravity Suit (an Integrative Countermeasure Device) Reduce
Images: icon  Fiscal Year: FY 2019 
Division: Human Research 
Research Discipline/Element:
HRP HHC:Human Health Countermeasures
Start Date: 10/04/2018  
End Date: 10/03/2020  
Task Last Updated: 10/30/2018 
Download report in PDF pdf
Principal Investigator/Affiliation:   Petersen, Lonnie  M.D., Ph.D. / University of California, San Diego 
Address:  Clinical Physiology Laboratory, Department of Orthopedic Surgery 
9452 Medical Center Dr, LL2 West 417 
La Jolla , CA 92037-1337 
Email: l8petersen@ucsd.edu 
Phone: 858-263-6365  
Congressional District: 52 
Web:  
Organization Type: UNIVERSITY 
Organization Name: University of California, San Diego 
Joint Agency:  
Comments:  
Co-Investigator(s)
Affiliation: 
Hargens, Alan  Ph.D. University of California, San Diego 
Levine, Benjamin  M.D., Ph.D. University of Texas Southwestern Medical Center at Dallas 
Project Information: Grant/Contract No. 80NSSC19K0020 
Responsible Center: NASA JSC 
Grant Monitor: Norsk, Peter  
Center Contact:  
Peter.norsk@nasa.gov 
Unique ID: 12051 
Solicitation / Funding Source: 2017 HERO 80JSC017N0001-Crew Health and Performance (FLAGSHIP1, OMNIBUS). Appendix A-Flagship1, Appendix B-Omnibus 
Grant/Contract No.: 80NSSC19K0020 
Project Type: GROUND 
Flight Program:  
TechPort: Yes 
No. of Post Docs:  
No. of PhD Candidates:  
No. of Master's Candidates:  
No. of Bachelor's Candidates:  
No. of PhD Degrees:  
No. of Master's Degrees:  
No. of Bachelor's Degrees:  
Human Research Program Elements: (1) HHC:Human Health Countermeasures
Human Research Program Risks: (1) SANS:Risk of Spaceflight Associated Neuro-ocular Syndrome (SANS)
Human Research Program Gaps: (1) SANS-301:Develop and test mechanical countermeasures in the laboratory.
Flight Assignment/Project Notes: NOTE: End date changed to 10/3/2020 per NSSC information (Ed., 10/28/19)

Task Description: Because all parts of human physiology are affected by microgravity, an integrative countermeasure strategy is needed. Loss of muscle and bone mass along with deconditioning of the heart and vessels are well described effects of microgravity. More recently structural and functional changes of the eye, experienced by some astronauts during long-term missions, have been described and summarized in the Spaceflight Associated Neuro-ocular Syndrome (SANS). While the exact etiology of SANS remains unknown, the microgravity induced headward fluid shift is likely part of the pathophysiology and countermeasures that can reverse this fluid shift are prioritized.

Based on our experimental data from short-term microgravity by parabolic flights and 24-hour simulated microgravity, we suggest that fluid redistribution in space may not give rise to a pathological increase in intracranial pressure, but rather the lack of diurnal fluctuations in intracranial volume and pressures may be responsible for the remodeling of the eye. In ambulatory neurosurgical patients with pressure sensors inserted in the brain tissue, we therefore demonstrated the feasibility of lower body negative pressure to reduce intracranial pressure as means of re-introducing diurnal pressure variability. Extending on this, in a recent 3-day, 6° head-down tilt bedrest trial we applied lower body negative pressure (LBNP) for 8 hours every day, to demonstrate safety and efficacy to significantly reduce long-term swelling at the back of the eye believed to be early symptoms of SANS.

At the University of California San Diego we have developed and tested a fully mobile "Gravity Suit" comprised of pressurized-trousers and attached vest. The suit simulates the effects of gravitational stress by application of low-levels lower body negative pressure to re-introduce an Earth-like fluid shift while at the same time inducing a ground reaction force at the bottom of the feet and a mechanical load along the entire body axis. Preliminary tests involving healthy human subjects in simulated microgravity have demonstrated the efficacy of 20 mmHg lower body negative pressure within the suit to reduce internal jugular vein cross-sectional area by some 45% and induce mechanical load of 57% bodyweight.

The intravehicular suit is comfortable enough to wear 8-10 hours a day and flexible enough to be combined with daily activity and even exercise with the overall aim to provide an integrative countermeasure. As an overall long-term aim, we suggest that use of the Gravity Suit will 1) re-introduce the diurnal variability of intracranial pressure and volume to help prevent development of SANS; 2) stimulate the cardiovascular system to maintain cardiac muscle mass and vascular compliance; 3) counteract loss of postural muscle mass and bone density; 4) finally, the axial loading will preserve curvature of the spine, paraspinal muscle, and disc morphology to both ameliorate in-flight back pain, and reduce risk of post-flight disc herniation.

Within the scope of this proposal, we will finalize and further test our prototype by integrating vacuum- and monitoring systems within the waist-belt to increase safety and allow for free and un-tethered movement. Comfort, range of motion, and gait will be assessed during relevant activities simulating daily work tasks on the International Space Station and in combination with resistive exercise device relevant for cislunar and deep space missions. High levels and/or prolonged exposure to lower body negative pressure can potentially compromise blood flow to the brain; however, activity and use of the muscle pump increases orthostatic tolerance. To establish a safe range and optimize the user scenario, we will test cardiovascular responses and cerebral perfusion during graded lower body negative pressure with and without a combined ground reaction force and in combination with rowing exercise. Successful funding of this proposal will bring our Gravity Suit to Countermeasure Readiness Level 7.

Research Impact/Earth Benefits:

Task Progress & Bibliography Information FY2019 
Task Progress: New project for FY2019.

Bibliography: Description: (Last Updated: 01/24/2024) 

Show Cumulative Bibliography
 
 None in FY 2019