NOTE: Project start date updated due to P.I. change to B. Macias. Information per C. Ribeiro/NASA-JSC. (Ed. 8/29/22).

Specific Aims:

1. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents ocular and cerebral structural changes during 30 days of strict 6° head-down tilt bedrest.

2. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents ocular functional changes during 30 days of strict 6° head-down tilt bedrest.

3. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents vascular and cerebrospinal fluid changes during 30 days of strict 6° head-down tilt bedrest.

This bedrest study will be implemented in the :envihab facility at the German Aerospace Center (DLR) in Cologne, Germany.

Personnel from the Cardiovascular and Vision Laboratory (CVL) traveled to the German Aerospace Center (DLR) five times to provide training and support before and during data collection. The purpose of the first visit was to provide in-person training sessions to DLR staff and to oversee baseline data collection (BDC) on the 12 subjects participating in the first campaign of the study. Additionally, due to unforeseen issues with the Dynamic Vessel Analyzer (DVA) hardware that resulted in the company being unable to train DLR staff prior to BDC as planned, a CVL team member collected all BDC data on the 12 subjects. CVL personnel then returned on an additional trip to collect recovery day 2 data (R+2) and continue training DLR staff to perform DVA measurements so that they could successfully collect data on R+12.

CVL personnel then traveled back to DLR prior to subject arrival for the start of Campaign 3 to provide in-person training to DLR staff for the new protocol involving VTCs. During the visit, the subjects' BDC began, and the CVL was present to observe and guide the VTC fit checks to ensure that subjects were fit with the correct size of cuff. Another visit occurred mid-way through Campaign 3 to observe how subjects and operators were doing with the VTCs. The final visit was during the BDC timeframe of Campaign 4 to train new operators and observe the VTC fit checks.

All data from the 4 bedrest campaigns have been imported into a study database and delivered to NASA Life Sciences Data Archive. The CVL also provided comprehensive lessons learned for future collaboration and bedrest studies at the facility.

Six publications to date have resulted from this study. Their references and summaries are listed below.

1. Moestl S et al. (2025). Mechanical countermeasures for spaceflight-associated neuro-ocular syndrome during 30-days of head down tilt bed rest: design, implementation, and tolerability. Front Physiol; DOI: 10.3389/fphys.2025.1530783.

2. He Y, Karanjia R, Zhang X, Wanderer D, Walker E, Lee SH, Poczatek MJ, O’Grady CS, Marion KM, Young M, Moestl S, Mulder E, Stern C, Sadda SR, Laurie SS, Macias BR, Huang AS. Optic nerve vasculature and countermeasure assessment in a bedrest analogue of spaceflight-associated neuro-ocular syndrome. Am J Ophthalmol. 2025;278, 317–327.

3. Hoenemann J-N, Moestl S, de Boni L, Hoffmann F, Arz M, Berger L, Pesta D, Heusser K, Mulder E, Lee SMC, Macias BR, Tank J, Jordan J. Cardiopulmonary deconditioning and plasma volume loss are not sufficient to provoke orthostatic hypertension. Hypertens Res. 2024;1–6.

4. Hönemann J-N, Hoffmann F, de Boni L, Gauger P, Mulder E, Möstl S, Heusser K, Schmitz M-T, Halbach M, Laurie SS, Lee SMC, Macias BR, Jordan J. Tank J. Impact of daily lower-body negative pressure or cycling followed by venous constrictive thigh cuffs on bedrest-induced orthostatic intolerance. J Am Heart Assoc. 2024;13:e034800.

5. Berger L, Mulder E, Zange J, Frings-Meuthen P, Frett T, Simon P, Hoenemann J-N, Poczatek MJ, Laurie SS, Huang AS, Macias B, Jordan J, Tank J, Rittweger J, Schmitz M-T, Pesta D. Aerobic exercise and subsequent venoconstrictive thigh cuffs preserve cardiorespiratory fitness but not muscle function after 30 days of bed rest. Med Sci Sports Exerc. 2025. DOI: 10.1249/MSS.0000000000003803.

6. Laurie SS et al. Daily use of countermeasures to prevent headward fluid shifts throughout 30 days of strict head-down tilt bed rest. J Appl Physiol Bethesda Md 1985. 2025;139:394–413.

NOTE: Project start date updated due to P.I. change to B. Macias. Information per C. Ribeiro/NASA-JSC. (Ed. 8/29/22).

Specific Aims:

1. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents ocular and cerebral structural changes during 30 days of strict 6° head-down tilt bedrest.

2. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents ocular functional changes during 30 days of strict 6° head-down tilt bedrest.

3. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents vascular and cerebrospinal fluid changes during 30 days of strict 6° head-down tilt bedrest.

This bedrest study will be implemented in the :envihab facility at the German Aerospace Center (DLR) in Cologne, Germany.

NOTE: Project start date updated due to P.I. change to B. Macias. Information per C. Ribeiro/NASA-JSC. (Ed. 8/29/22).

Specific Aims:

1. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents ocular and cerebral structural changes during 30 days of strict 6° head-down tilt bedrest.

2. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents ocular functional changes during 30 days of strict 6° head-down tilt bedrest.

3. To determine if daily exposure to actual (upright posture) and simulated (LBNP) hydrostatic pressure gradients prevents vascular and cerebrospinal fluid changes during 30 days of strict 6° head-down tilt bedrest.

This bedrest study will be implemented in the :envihab facility at the German Aerospace Center (DLR) in Cologne, Germany.

March 2023 Update on Task Status (Ed., 1/3/24)

Data collection has been completed for campaigns 3 (January-March 2023) and campaign 4 preparations are underway (planned data collection May-July 2023). In campaign 3, 6 subjects in each of the Control and Exercise plus thigh cuff groups completed data collection, with 12 additional subjects being planned for campaign 4. In this reporting period, personnel from the Cardiovascular and Vision Laboratory (CVL) traveled to the German Aerospace Center (DLR) to provide in-person training sessions to DLR staff and to oversee baseline data collection (BDC) on the 12 subjects who participated in campaign 3 of the study. Key aspects of training included countermeasure protocol development and new ultrasound targets of the femoral artery and vein related to the new thigh cuff countermeasure. The majority of data has been received by the CVL, with a few final pieces expected in the coming weeks. Data analysis was accelerated for optical coherence tomography (OCT) outcomes and the new ultrasound targets. Hand entry of multiple outcome variables has also been initiated.