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Published on: January 20, 2019
Development of a Sitting MicroEnvironment Simulator for wheelchair cushion assessment
Tyler Freeto1, Allissa Cypress2, Sarah Amalraj2
1Advanced Platform Technology Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
Study Aim:
Pressure ulcers (PU) are a common comorbidity among wheelchair users. An appropriate wheelchair cushion is essential to relieve pressure and reduce PU development during sitting. The microenvironment, specifically excessive heat and moisture, impacts risk for PU development. An effective wheelchair cushion should maintain a healthy microenvironment at the seating interface. Measurement of heat and moisture can characterize microenvironmental conditions at the wheelchair cushion interface under load. We describe the development of a Sitting MicroEnvironment Simulator (SMES) for the reliable assessment of wheelchair cushion microenvironments.
Materials:
The prototype SMES was developed for use mounted on a Materials Testing Systems (MTS) 810(®) uniaxial servo-hydraulic loading rig and used to assess microenvironmental conditions for Jay Medical Jay 2(®), Roho High Profile Dry Floatation(®) and Low Profile Dry Floatation(®) cushions and a novel modular gel cushion.
Methods:
Each cushion was assessed for two hours in triplicate. The SMES was used to load the cushions to 300N ± 10N, with an interface surface temperature of 37 °C±1 °C and fluid delivery of 13 mL/h±1 mL/h of water. Interface temperature and humidity were measured at the left ischial tuberosity (IT) region every five minutes.
Results:
Heat and moisture responses were similar for the three commercial cushions. The modular gel cushion stayed cooler for at least 15 min longer than any commercial cushion.
Conclusions:
The SMES maintained performance to technical specifications for over one hundred hours of total testing and is a reliable tool for characterizing the microenvironmental conditions of wheelchair cushions.
