The investigation of early classification of pressure ulcers using computer image analysis for early prognostic assessment

A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of PhilosophyPressure sore prevention is becoming a very important issue due to the cost of nursing time, quality assurance and possible litigation. Recent government reports Essence of Care (2001) and National Institute for Clinical Excellence Pressure ulcer risk assessment and prevention (2001) focus on pressure ulcers as a measurable outcome. Correct classification of the early stage of a pressure ulcer is essential, in order to instigate early interventions to prevent further pressure damage. This thesis had four studies: " The first study examines statistical evidence of the efficacy of two alternating mattresses. A randomised controlled trial of 141 Care of Elderly Patients who were assessed to have Torrance grade 2 and above pressure ulcers (71 on Cairwave, 70 on Nimbus 3). The secondary aim was to determine whether availability of extra pressure relief equipment would reduce the incidence of ulcers in an acute hospital. " The second study investigated healing rates on the alternating mattress. This was measured using digital image analysis macro. Precision of image analysis assessed by within- and between-batch Coefficients of Variation was excellent: Calibration CV 0.93 - 1.84%; Area CV 4.61 - 5.72%. ". The third study was a descriptive study using a questionnaire and twelve digital photographs classified by 200 subjects using two classification systems, the European Pressure Ulcer Advisory Panel and Stirling plus digits. The expert panel comprised of 5 tissue viability specialists / clinical lecturers in tissue viability with many years of collective experience were used as the gold standard to classify the questionnaire digital photographs. " The fourth study used data from the original randomised control clinical trial of Pegasus Cairwave & proactive seating cushion and the Nimbus 3& Aura seating cushion for the treatment of pressure ulcers. The data was examined to determine whether there are any common factors relating Hue Saturation and Intensity and a particular grade of pressure ulcers. Overall, in studies 1 and 2 it was demonstrated that the Nimbus 3 was better at treating heel ulcers but both mattresses help treat sacral pressure ulcers at approximately the same rate. The questionnaire demonstrated that there is considerable lack of consensus when pressure ulcers are graded using the Stirling plus digit grading system, and less disagreement when the EPUAP scale is used. Clinical Nurse Specialists in Tissue Viability were keen to receive extra education, whilst ward nurses were happy with their current knowledge and did not believe further education on pressure ulcers was required. The final study demonstrated that the computer was able to identify early pressure ulcer formation with reasonable accuracy disparate. Using the information from the consensus panel, demonstrated a positive correlation between the computerized model and the panel's grades of pressure ulcers