Comparing Wheelchair Cushions for Effectiveness of Pressure Relief: A Pilot Study

The purpose of this study was to determine if there were differences in pressure relieving abilities among six commonly prescribed wheelchair cushions and whether differences were related to the participant's body mass. In addition, the participant's perception of cushion comfort was investigated. A convenience sample of 40 adult wheelchair users were recruited from a rehabilitation hospital. Participants sat on the following six cushions for 5 minute periods: Flexseat, Jay 2, Pindot, ROHO High, ROHO Low, and Stimulite. Pressure measurements were recorded with the Xsensor Pressure Mapping System, a new instrument available to therapists. It was discovered that ROHO High and ROHO Low cushions were more effective in relieving pressure than the other cushions. Cushion pressure relieving abilities were largely dependent on the individual's body mass. ROHO cushions were also perceived to be more comfortable than all other cushions tested regardless of body mass and pressure relief. Orit Shechtman, PhD, OTR; Carolyn S. Hanson, PhD, OTR; and Donna Garrett, MHS, OTR are from the Department of Occupational Therapy, University of Florida, Gainesville, Florida. Pam Dunn, MS, OTR/L, is Wheelchair Clinic Specialist, Brooks Rehab Hospital, Jacksonville, Florida. The Occupational Therapy Journal of Research Winter 2001, Volume 21, Number 1 Decubitus ulcers, also known as pressure ulcers and pressure sores, are a frequent and serious complication for many long-term wheelchair users that disrupt every aspect of a person's life, affecting health, employment, education, and social interaction (Springle, Faisant, & Chung, 1990). Kuhn and Coulter (1993) estimated that 1.7 million patients develop new pressure sores annually, with associated expenditures of 8.5 billion dollars. The costs of preventing pressure sores, however, are significantly less than the costs of treatment. Decubitus ulcers develop mainly as a result of disruption to the vascular network of arteries, arterioles, and capillaries (Bridel, 1993). Although impaired metabolism, friction, and shear forces have been shown to be instrumental in the pathogenesis of decubi-tus ulcers, prolonged supracapillary pressure appears to play the most important role (Bridel, 1993; Dinsdale, 1974; Kosiak, 1958). In his landmark work, Kosiak (1959) demonstrated an inverse relationship between the minimal time arid the minimal pressure needed to produce a decubitus ulcer. It has since been established that redness persisting for 24 hours or more is a stage I decubitus, and if pressure is not removed entirely, such an area frequently proceeds to ulceration (Delateur, Berni, Hongladarom, & Giaconi, 1976). Kdsiak's studies proved what has come to be well known and accepted among the medical community—duration of pressure is actually more critical than intensity. Proportionately lower pressures produce equivalent tissue damage with increasing duration of application (Souther, Carr, & Vistnes, 1974). Foremost in the prevention and treatment of decubitus ulcers is the prescription of pressure relieving devices such as wheelchair cushions designed to distribute the body's weight away from the areas most vulnerable to tissue erosion. The knowledge and expertise to prescribe these devices usually lies with the rehabilitation staff and includes occupational and physical therapists (Garber, 1979). A primary objective of occupational therapy is to maximize functional potential in patients with impairment and disability. Pressure sores are a major complication in the rehabilitation of these individuals (Garber, 1985b). The occupational therapy perspective or practice model that the therapist uses to organize the many aspects of this complication will influence what the therapist measures, which variables she or he chooses to treat, and what conclusions are drawn. The rehabilitative conceptual model of practice is applicable to patients with the potential complication of decubitus ulcers secondary to impaired mobility and sensation because it addresses problems at the disability and handicap levels of disablement and aims at making the person as independent as possible inspite of residual disability. The rehabilitative model is used when remediation is incomplete or impossible and focuses on teaching adaptation so that the person may become an active partner in his or her health (Trombly, 1995). Knowledge of the causes and treatment of decubitus ulcers is therefore essential for the occupational therapist, and effective methods of prevention are critical if occupational therapy is to be instrumental in bringing about rehabilitation through adaptation in persons at potential risk for decubitus ulcers. To aid in the decision, the therapist employs various strategies to select a patient's wheelchair cushion, including the objective assessment of pressure between the patient's buttocks and the seating surface and also clinical judgment including diagnosis and analysis of lifestyle factors. Since the successful selection of the proper wheel-chair cushion for a particular patient cannot be based on objective data or clinical judgment alone, it becomes obvious that individualized prescription must be a combination of objective information provided by a pressure-detecting instrument and skilled clinical assessment (Garber, 1985b). In addition to a therapist's judgment, patient preference must always be considered in the cushion selection process, especially the patient's perception of comfort of the cushion. A cushion, regardless of its ability to relieve pressure, is unlikely to be used if the patient feels that it is uncomfortable. Also, no studies have yet examined the relationship between a person's assessment of cushion comfort and the cushion's actual pressure relieving ability. Once a pressure relieving wheelchair cushion has been carefully selected and prescribed, it is often the occupational therapist who is responsible for training the patient and family in proper, cushion use, positioning, care, and maintenance. Many decubitus ulcers have developed when a patient has sat on a deflated air type cushion for a period of time, or has unknowingly reversed the cushion and sat on the abductor wedge. A major goal, therefore, of occupational therapy is consumer education. Consumers need to know the characteristics of the many types of cushions available and the advantages and disadvantages of each cushion being considered. Data suggest that periodic reevaluation of patients by their therapist is essential to detect changes in lifestyle, general health, and skin integrity in order to prevent the development of decubitus ulcers (Garber & Krouskop, 1982). It must be realized that cushion prescription is not a one time occurrence, and changes may be necessitated by a patient's alteration in health status, body build, mobility level, or activity pattern. In recent years, hundreds of commercially available seating devices have been developed and marketed, creating an urgent need for therapists to better understand this technology (Garber, 1985a). Although specially designed pressure relieving wheelchair cushions have been manufactured and widely prescribed, little research (Rosenthal, Felton, Hileman, Lee, Friedman, & Navach, 1996) examining the relative effectiveness of these cushions has been conducted within the last 5 years. Earlier studies comparing the pressure relieving abilities of various cushioning technologies examined cushions that are no longer manufactured or prescribed, with the exception of ROHO and Jay products (Fisher & Patterson, 1983; Garber, 1985b; Garber, Krouskop, & Carter, 1978). Since the 1970s, several pressure-mapping systems have been employed in clinical research studies to compare commonly prescribed pressure relieving wheelchair cushions (Rosenthal et al., 1996; Fisher & Patterson, 1983; Garber, 1985b; Garber et al., 1978). These evaluation systems, however, were impractical to mass-produce, cumbersome to operate, and not readily available for use in the clinic. The technology of both wheelchair cushions and pressure detection instrumentation has changed dramatically in recent time. The availability of pressure detection instrumentation in the clinical setting may allow therapists to make informed decisions in choosing appropriate cushions for specific patients. Indeed, the idea for this project was conceived out of clinicians' interest in scientific inquiry of optimum patient care. This pilot study was conducted in a wheelchair clinic to investigate the capabilities of a recently purchased pressure detection system (the Xsensor Pressure Mapping System) designed to determine differences in pressure among wheelchair cushions. The purpose of this study was to investigate whether there were differences in the pressure relieving abilities of six wheelchair cushions currently on the market. Also, we investigated whether the pressure relieving abilities of these cushions were related to the participant's body mass, and whether the participant's opinion regarding'the comfort of the cushions corresponded to the objective measure of pressure relief provided by the cushions.