A PROPOSED LOW COST CUSHION DESIGN FOR INDIVIDUALS WITH SPINAL CORD INJURY IN DEVELOPING COUNTRIES

Nigel Shapcott, Dave Cooper, Jess Gonzalez, Alan Haddow, Mike Heinrich, Diane Hobley, Dave Savage
Post International Seating Symposium Sore Butts Working Group

ABSTRACT

A group of interested individuals has met after the last two International Seating Symposiums (Vancouver'94, Pittsburgh'95) to brainstorm and create strategies for devices and educational efforts aimed at reducing the problem of pressure sores after spinal cord injury. This paper describes a prototype low cost cushion design, using commonly available materials, which may have some relevance for individuals with spinal cord injury in developing countries. This prototype effort relates directly to the Sore Butts Cushion Design Competition which is under development by RESNA's International Appropriate Technology Special Interest Group (SIG17).

BACKGROUND

Pressure relieving cushions have been used in the management of spinal cord injury for many years and are provided as part of the rehabilitation process routinely. They fall into broad catagories: contoured (standard shape or customized) which can be made of many different materials ranging from foam to cardboard; flat (normally foam or gel); air flotation; liquid flotation; gel; and combinations of the above.

STATEMENT OF THE PROBLEM

In developing countries spinal cord injuries are normally (80%) followed by death within 2 years as a result of pressure sore related problems, (1). Previous work related to low cost pressure measurement techniques (2) and vacuum consolidation (3) have attempted to address some aspects of the problem. Hotchkiss has developed a low cost cushion fabricated from layers of cardboard which is shaped by sitting pressures and carving to form a custom contoured cushion. His main problem with this is that the time it takes to manufacture a single cushion makes it an unattractive option. In Western countries mass production of cushions (and thus ready availability) is the standard approach with customization being reserved only for the most difficult problems, however most of these cushions vary in cost from $200-$400 dollars which is totally inappropriate for the target markets. As a price comparison, low cost devices which aid in the rehabilitation process, such as wheelchairs locally manufactured for about $150 are being successfully introduced in some countries (4).

RATIONALE

The International Appropriate Technology Special Interest Group (SIG17) within RESNA have for the past two years attempted to develop strategies which might address some of the issues related to pressure sore prevention. One of the strategies to emerge has been the development of the "Sore Butts Competition".

The purpose of this competition is to stimulate ideas for such devices that could be manufactured in the required locality, by the local population. It is envisaged that this competition will be run annually, resulting in evolving prototypes that will be of use in a variety of different settings.

This paper describes the development of a prototype low cost pressure relieving cushion for individuals with spinal cord injury, in order to provide insight into techniques which might reduce the incidence of pressure problems in this population. This prototyping experience helped in the development of the rules for the Sore Butts Competition.

DESIGN & DEVELOPMENT

Goals

The purpose of this work was to identify principles and techniques which may help to reduce the incidence of pressure sores amongst individuals with SCI in developing countries.

The group met in two sessions.

Session 1

Construction of prototypes and pressure measurement using the FSA Pressure Pad (5). Various combinations of the following devices and techniques were tested.

• Inner tube frame Air Flotn.

• Chicken wire frame Contoured

• Towel Flat

• Beach ball- partially inflated Air Flotn.

• Wire frame Contoured

The conclusions of the group were that the most effective of these was the beach ball in combination with some contouring to provide additional support, in this case a towel folded to provide a pre-ischial bar. The following conclusions came out of further discussion and measurement and identified the basic ingredients of a proposed SCI survival kit.

• Beach ball (cushion component)

• Towel (cushion component)

• Balloon and tube (pressure measurement(2))

• Bag (calibration and container)

• Educational material (how to be healthy)

Session 2

Discussion on the proposed SCI survival kit led to the following refinements.

Beach ball

• This is one of the main cushion components and is a partially filled, non extensible air container.

• It is suggested that 2 would be provided, one in use and wrapped in pre-ischial bar as a spare, our tests used a 49" circumference beach ball.

Towel

• This is the second major cushion component, size 27'X50", made from toweling, folded to 4 layers and rolled to form pre-ischial bar. The functions of the towel are to form pre-ischial bar for pelvic positioning and to cover over the beach ball to provide some cushioning in the event of accidental deflation.

Cushion Cover/Bag

• This is the third major component. A simple cotton or similar material bag constructed with 2 draw strings, which enable it to fulfill three functions: a calibration function- to ensure approximately 4-5 US quarts Volume of air is in the beach ball; a container in which to ship/transport the kit; and a cushion cover, to cover the toweling pre-ischial bar and beach ball and maintain their position on the wheelchair.

Balloon and tube Pressure measurement

• As previously defined and in current use (2) for ensuring safe sitting pressures.

Educational Material

• This has still to be developed to provide individuals with guidance on how to stay healthy with a spinal cord injury, how to maintain cushion function and the purpose and process of carrying out sitting pressure measurement.

Vinyl repair kit

• It is likely that any flexible air containing cushion will be damaged accidentally at some time. The vinyl repair kit will enable beach ball repair as necessary.

EVALUATION

Evaluation of the beach ball and pre-ischial bar toweling cushion was carried out using the Force Sensor Array (FSA) pressure measurement mat and was limited to one individual with a C6-7 spinal cord injury measured in the following configurations on the individuals regular Quickie 2 wheelchair.

• Contour/gel cushion

• Wheelchair Sling

• Partially Inflated Beach ball

• Partially Inflated Beach ball and Towel

• Sling and Towel

• Experience clinicians interpreted the data and concluded that, for this individual, the partially inflated beach ball and towel provided the lowest pressure readings.

• It should be noted however that the disabled user felt unstable and would require additional lateral pelvic stabilization for longer term testing.

DISCUSSION

Surprisingly low pressures were achieved with a partially inflated (49" inflated circumference) beach ball based cushion. The pressure readout was very even. Casual observation indicated a "flat" ball, however 1 US gallon of air was the measured volumetric content of the beach ball, this allowed for a great deal of surplus beach ball material in the form of wrinkles which appeared to have prevented hammocking effects. Beach balls can be purchased by the dozen for about $10.00. With the cost of a towel, cover and other materials identified in Session 2 (above) it is likely that a cushion kit could be assembled for about $10.

Further evaluation work is necessary before a design can be finalized.

REFERENCES

(1) Hotchkiss R, Personal communication.

(2) Shapcott N., Cooper D., Heinrich M.

"Low Cost Pressure Measurement Technique For Individuals With Spinal Cord Injury". Proceedings RESNA 1994

(3) Jess P. Gonzalez, Nigel Shapcott

"A Low Cost Vacuum Consolidation System To Facilitate Seating Evaluations". Proceedings RESNA 1994

(4) Hotchkiss R., Independence through Mobility: A Guide to the Manufacture of the ATI- Hotchkiss Wheelchair. Appropriate Technology International. Washington, DC.

(5)) Vistamed, Box 23058- 1315 Pembina Hwy., Winnipeg, Manitoba, Canada, R3T 5S3. Force Sensing Array; Piezoelectric, multiple cell, continuous measurement.

ACKNOWLEDGEMENTS

SHRS, Rehabilitation Engineering Program, University of Pittsburgh for the loan of testing and recording equipment. Andy Frank, Vistamed for software support.