A new perspective in clinical assessment of seat interface pressure measurement

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A new perspective in clinical assessment of seat interface pressure measurement


Author: Ng, Hoi-kwai Vincent
Title: A new perspective in clinical assessment of seat interface pressure measurement
Degree: M.Sc.
Year: 2002
Subject: Hong Kong Polytechnic University -- Dissertations
Sitting position -- Health aspects
Wheelchairs -- Physiological aspects
Pressure -- Measurement
Department: Jockey Club Rehabilitation Engineering Centre
Pages: ix, 52 leaves : ill. (some col.) ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1659573
URI: http://theses.lib.polyu.edu.hk/handle/200/198
Abstract: Wheelchair users have a high prevalence in developing pressure ulcers, partly because the interface pressure over Ischial Tuberosity (IT) is higher when they assume a sitting position. They sit on the wheelchair for a long period of time during the day and some has limited ability to perform pressure relief. As a preventive measure, proper choice of pressure relief cushions as well as proper adjustment of wheelchair is of equal importance in clinical practice. Unfortunately, the effectiveness of these preventive measures is still dependent on the experience of individual therapist and most of the evaluations performed in clinical settings are rather subjective. With the availability of pressure mapping system in recent advancement of technology, clinician can objectively measure, and determine whether these interfacial pressures are within the acceptable level based on the findings of published literatures. Interface pressure measurement during clinical examination is usually conducted in one single sitting position, which may cause under estimation of the tissue distresses resulting from other daily activities like wheelchair maneuvering. This study aims to measure the seat interface pressure continuously when the wheelchair user performs three common wheelchair activities using a portable pressure measurement system. Peak and average pressure under the IT was evaluated and compared between static and dynamic situations using paired t-test. The change of peak pressure and average pressure over the IT in three wheelchair activities (level propulsion, push up slope and down-kerb) were evaluated using repeated measures ANOVA. It was found that both peak and average pressure over Ischial Tuberosities during continuous measurement were significantly higher (p>0.05) than the results from traditional static measurement. Therefore, clinicians should consider a higher safety limit when just assessing the patient in a static situation or consider use of a continuous measurement method. Among the three activities, there is significant difference between Slope and Down kerb, with down kerb activity being 42% higher in average pressure ( F(1,16) = 7.427 p = 0.0l5) and 29% higher in peak pressure ( F(1,16) = 8.854 p =0.09). There is also significant difference found in peak and average pressures between Level Propulsion and Down Kerb activity Down Kerb activity was found to be 48% higher in average pressure ( F(1,16) = 11.486 p = 0.04) and 46% higher in peak pressure ( F(1,16) = 8.099 p = 0.0l2). These findings demonstrated that interface pressure over the IT is higher when the wheelchair users perform their daily activities, as compared to sitting in astatic position. For some vigorous activities such as down kerb, it even has a significantly higher pressure than the usual activities such as propelling the wheelchair. This study suggests a new perspective in assessing the seat interface pressure using a continuous measurement method. However, the effect of the intermittent high pressure on tissue damage as revealed during dynamic assessment is still not clear. Further research is required to gain better understanding on the potential risk of pressure sore resulting from dynamic wheelchair activities.

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