ANALYSIS OF ARTERIAL FLOWMOTION IN SPINAL-CORD INJURED AND ELDERLY SUBJECTS IN AN AREA AT RISK FOR THE DEVELOPMENT OF PRESSURE SORES

Flowmotion (blood flow changes due to vasomotion) in the skin over a r isk area for pressure sores, the sacrum, and a non-risk area, the glut eus muscle, was evaluated by laser Doppler fluxmetry during resting co nditions and post-occlusive reactive hyperaemia (PRH) response. Measur ements were made in healthy younger subjects and in two risk groups fo r pressure sores-spinal cord injured (SCI) and the elderly. The SCI we re divided into two subgroups, one with and one without distinct flowm otion seen on the original recordings over the sacrum. The Prony spect ral line estimation (PSLE) method was used to determine the power spec trum of the flowmotion activity. During the PRH, flowmotion frequencie s were found in two separated bands, 5.4-6.6 cpm (cycles min(-1)) and 7.8-9.0 cpm. In the subgroup without distinct flowmotion, the PSLE met hod found flowmotion frequencies similar to the other groups. During t he PRH, the flowmotion power pattern over the sacrum was similar withi n all groups, but the power was extremely low in one subgroup of SCI s ubjects. To conclude, flowmotion (vasomotion) was present in the two s kin areas and increased during the PRH response, reaching a maximum wi thin 50 s. This study shows that the flowmotion frequencies might be l ocally driven, whereas the power might be centrally mediated. Disturba nces in microcirculatory flowmotion can be a part of the mechanisms le ading to skin ischaemia and pressure sores. A new method has been deve loped for analysing differences in flowmotion behaviour such that stat istical comparisons can be made.