Thermographic studies of tissue trauma and seating
Wheelchair sitters with insensitive skin have a high risk of developing pressure sores. Prolonged pressure produces ischaemic conditions in the underlying tissues which may lead to cellular death and necrosis. Properly designed seating may reduce this risk and prevent the onset of pressure sores. To achieve the best protection possible a method of objective evaluation is required which will account for variations in tissue quality, sitting behaviour and sitting biomechanics. This thesis reports on the application of thermography into a tissue trauma seating programme and the quantification of isotherm areas for statistical comparisons of skin temperature response to experimental parameters. The thermographic research is presented in three phases of analysis: Chapter 4, a retrospective study of thermograms based on maximum temperatures; Chapter 5 both maximum temperatures from the real-time thermograph display and automatically collected areameter isotherm area data; and Chapter 6, a prospective patient study based on isotherm area data. During the preliminary stages of research, patients were followed with thermographic examinations at various stages of fitting and trial sitting on wheelchair cushions. There followed a series of tests with able-bodied subjects on experimental seats in an environmental chamber to determine the minimum conditions required for quantitative measurement of thermographic data. The examination room at the Ontario Crippled Children's Centre was then modified accordingly for patient studies and quantitative techniques were tested further. The results of these three phases of reseach are presented with recommendations for continuing studies. The acquired information supports the use of thermography in tissue trauma programmes. Sites of accumulated stress were found to be identifiable and approaches tor the quantitative comparison of thermal response to sate and unsafe loading conditions presented. Maximum temperatures were the most sensitive measures of hyperthermic response and mean imaged temperatures, the most readily characterized for cooling. Detailed discrimination of differences in skin cooling were found to be enhanced when the area of examination was minimized.