Sequence showing uniform bladder deflation for consistent pressure off loading. The bladders are made of polyurethane foam with a seam sealed urethane cover.

The profile of the bladder, as well as multiple stiffnesses of the cover, help ensure uniform deflation.

A double-layer base ensures internal circulation for uniform deflation. There are about 15 iterations for the bladder design, optimizing foam stiffness, cover material, and base design.

This iteration incorporated piezoelectric thermocouples to dissipate heat from within the bladder in an attempt to control the microclimate within the cushion.

All the components--pump, battery, valves, electronics--are contained within the cushion in a shell under the thighs.

Pressure mapping showing full loading on left, and offloading with deflated bladders on right.

Built through a collaboration of researchers, engineers, and clinicians at CATEA. Above picture: the contour is based on anthropometry to ensure good postural support an dpressure distribution. This version is shown with a silicon impregnated reticulated polyurethane foam.

For additional information, please contact:
Lauren MacLanahan - 404.894.6900
Office of Technology Licensing
Georgia Institute of Technology

Description
A self-contained dynamic off-loading wheelchair cushion, designed to alleviate pressure under the primary at-risk sites for the seated individual: the ischial tuberosities and coccyx/sacrum.

Background
Most alternating pressure wheelchair cushions on the market currently are designed similar to alternating pressure mattresses. Adjacent components alternate between high and low inflation to sequentially raise and lower pressure. In contrast, this project is based upon unique patented technology (US Patent 6,367,106 Therapeutic support for the reduction of decubitus ulcers). The cushion incorporates three bladders, which are deflated via a vacuum pump to vary loading on the buttock tissues. Further, the cushion uses programmable electronics which allows customization of a pressure relief schedule. The Mobility RERC has partnered with the patent holder, Z Development, to optimize design features and demonstrate clinical utility.

System Characteristics
• Low cost: Cost of goods $150-175, Target retail $750- $875
• Portable: Cushion is battery operated & components are self contained.
• Battery life: The cushion will operate for up to 16 hours.
• Weight: Total cushion weight ≤ 9 pounds.


Market Opportunity
Sale of such a cushion would be to individuals, as well as to health care facilities with a focus in wound healing. This cushion could be an integral component of acute rehabilitation status post pressure ulcer surgery. The target end user population consists of any wheelchair user with a current pressure ulcer or at high risk of pressure ulcer development due to impaired mobility and sensation, especially those with history of a pressure ulcer or ulcers. A HCPCS code exists for alternating pressure cushions, but CMS has determined that medical benefit has not been demonstrated for this category of cushions. The dynamic off-loading cushion is uniquely designed for clinical research as the programmable electronics allow for complete customization of the duty cycle to determine an optimal pressure relief schedule.

Prototypes
Every aspect of this cushion has been tested and tweaked to ensure it's performance. Different sized pumps and batteries were tested to run all day. The bladders were tested for 50,000 cycles to determine fatigue of the inner foam and outer shell. And the cushion in it's entirety was tested with an array of pressure sensors, doppler, and acoustic probes, to verify pressure release of the bony prominences as well as blood flow in the surrounding tissue.