PhD ThesisThe thesis comprises literature reviews which present arguments novel to the field
and two discrete but related studies, which in combination make a contribution to the
classification, assessment of risk and prevention of pressure sores.
The first study, a randomised controlled trial involving 446 patients undergoing
vascular, general and gynaecology surgery, the use of a dry visco-elastic polymer
pad intra-operatively reduced the probability of pressure sore development by half.
Pressure sore incidence was 11 % (22/205) for patients allocated to the dry polymer
pad and 20% (43/211) for patients allocated to the standard operating table mattress.
Both studies explored key prognostic factors using multi-variate methods. Analysis of
data derived from the randomised controlled trial found four factors to be
independently associated with post-operative pressure sore development including
intra-operative hypotensive episodes, Day I Braden mobility scale and intraoperative
mean core temperature. The second study, a prospective cohort study
involving 101 patients identified non-blanching erythema, pre-operative albumin,
weight loss preceding admission and intra-operative minimum diastolic blood
pressure. Results are consistent with findings from the literature review which
identified key factors in the prediction of pressure sore development (reduced
mobility, nutrition, perfusion, age and skin condition).
The second study also explored the clinical significance of erythema in defining and
classifying the term 'pressure sore'. Using laser Doppler imaging it was determined
that blanching and non-blanching erythema are characterised by high blood flow of
differing intensity. Discriminant analysis identified three general patterns in skin blood
flow, which enabled scan classification with good agreement between clinical and
predicted classifications. The results confirm data derived from the prospective
observations of skin suggesting that non-blanching erythema is not indicative of
irreversible ischaemic damage and resolves in approximately two thirds of cases.
The point at which non-blanching erythema becomes irreversible remains unknownNHSE Northern and Yorkshire:
Tissue Viability Research Training Fellowship:
NHSE Northern and Yorkshire Research Capacity Committee:
Smith and Nephew Foundation Research Fellowship