Mobile Lower Body Negative Pressure Suit as an Integrative Countermeasure for Spaceflight

Area of Science:

• Space Medicine
• Human Physiology
• Biomedical Engineering

Background:

• Long-term spaceflight causes deconditioning due to fluid shifts and lack of mechanical loading.
• Lower body negative pressure (LBNP) can counteract these effects by promoting fluid shift and mechanical loading.
• Existing LBNP methods are often cumbersome and limit mobility.

Purpose of the Study:

• To design, build, and test a wearable, mobile, and flexible LBNP device (GravitySuit).
• To assess the GravitySuit's ability to induce mechanical loading and fluid shift.
• To evaluate cardiovascular responses and subject comfort during LBNP application.

Main Methods:

• Developed a GravitySuit with pressurized trousers and a thoracic vest.
• Eight healthy subjects underwent testing with the GravitySuit.
• Measured ground reaction forces, cardiovascular parameters, and internal jugular venous area (IJVa) using ultrasound.

Main Results:

• LBNP up to 40 mmHg induced axial loading from 13% to 125% of bodyweight.
• LBNP significantly reduced IJVa, indicating footward fluid shift.
• Moderate LBNP (30-40 mmHg) altered stroke volume and heart rate; cardiac output and mean arterial pressure remained stable.

Conclusions:

• The flexible GravitySuit comfortably induces mechanical loading and fluid displacement.
• The device maintains mobility of hip and knee joints.
• GravitySuit offers a feasible, integrative countermeasure for long-duration spaceflight.