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- Källman, Ulrika, 1968-
(författare)
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Evaluation of Repositioning in Pressure Ulcer Prevention
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: To reduce the risk for pressure ulcers, repositioning of immobile patients is an important standard nursing practice. However, knowledge on how this preventive intervention is carried out among elderly immobile patients is limited and to what extent patients perform minor movements between nursing staff-induced repositionings is largely unknown, but these movements might have implications for the repositioning intervention. Different lying positions are used in repositioning schedules, but there is lack of evidence to recommend specific positions.Aim: The overall aim of this thesis was to describe and evaluate how repositioning procedures work in practice in the care of elderly immobile patients. The aim was also to compare the effects of different positions with regard to interface pressure, skin temperature, and tissue blood flow in elderly patients lying on a pressure-redistribution mattress.Methods: This thesis consists of four quantitative studies. In Study I, 62 elderly immobile patients were included. All movements the patients made, either with help from the nursing staff or spontaneously, were registered continuously over the course of three days. Study II served to pilot the procedure for Study III. Tissue blood flow and skin temperature were measured in hospital patients (n = 20) for 5 minutes in two supine, two semi-Fowler, and two lateral positions. In Study III, a new sample was recruited (n = 25) from three nursing homes. Measurement of interface pressure was added, and the measurements were extended from 5 minutes to 1 hour. The six positions were reduced to four by excluding the two semi-Fowler positions. Blood flow was measured using photopletysmography (Study II-IV) and laser Doppler flowmetry (Studies III and IV). In Study IV a deeper analysis of the individual pressure-induced vasodilation (PIV) responses was performed on the sample from Study III. An age of 65 years or older was an inclusion criterion in all studies.Results: Study I showed that there was a large variation in the extent to which the elderly immobile patients made spontaneous movements, and these movements were positively related to taking analgesics and negatively related to taking psycholeptics. Patients scored as high risk for pressure ulcer development were repositioned more frequently than patients scored as low risk. However, the spontaneous movement frequency was not associated with any risk scores. Study II showed that the different lying positions influenced the blood flow in different ways. In Study III, it was found that the overall blood flow response during one hour of loading was significantly higher in the 30° supine tilt position than in the 0° supine, 30° lateral, and 90° lateral positions. The overall blood flow in the 90° lateral position did not differ compared to the 30° lateral position, although the interface pressure was significant higher in the 90° lateral position. In patients lacking a PIV response (Study IV), the blood flow decreased immediately and remained below baseline during the one hour of loading.Conclusions: Although elderly and immobilized, some patients frequently perform minor movements while others do not. Patients who cannot perform minor movements are important for the nursing staff to identify because they very likely need more intensive repositioning interventions. The spontaneous movement frequency was not associated with the risk assessment score, and this implies that some immobile patients assessed as low risk might need to be repositioned as often as patients assessed as high risk. Of the positions evaluated, the 30° supine tilt position was concluded to be most beneficial. There was no great difference in how the blood flow was affected in the 90° lateral position compared to the 30° lateral position, which question the appropriateness of the recommendation to avoid the 90° lateral position. The patients with lacking a PIV response might be particularly vulnerable to pressure, which also implies that these patients might need to be repositioned more frequently.
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| 2. |
- Bergstrand, Sara, 1978-
(författare)
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Preventing pressure ulcers by assessment of the microcirculation in tissue exposed to pressure
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this thesis was to combine optical methods into a system with the ability to simultaneously measure blood flow changes at different tissue depths. The goal of such a system was to reveal vascular mechanisms relevant to pressure ulcer etiology under clinically relevant conditions and in relation to the evaluation of pressure-redistribution support surfaces.This thesis consists of four quantitative, cross-sectional studies measuring blood flow responses before, during, and after pressure exposure of the sacral tissue. Two optical methods – photoplethysmography and laser Doppler flowmetry – were combined in a newly developed system that has the ability to discriminate blood flows at different tissue depths. Studies I and II explored blood flow responses at different depths in 17 individuals. In Study I the blood flow was related to tissue thickness and tissue compression during pressure exposure of ≥ 220 mmHg. In Study II, the sacral tissue was loaded with 37.5 mmHg and 50.0 mmHg, and the variation in blood flow was measured. Studies III and IV included 42 healthy individuals < 65 years, 38 healthy individuals ≥ 65 years, and 35 patients ≥ 65 years. Study III included between-subject comparisons of blood flow and pressure between individuals in the three study groups lying in supine positions on a standard hospital mattress. Study IV added within-subject comparisons while the individual was lying on four different types of mattress. The studies explored the vascular phenomena pressure-induced vasodilation (PIV) and reactive hyperemia (RH).The most common blood flow response to tissue exposure in this thesis was PIV, although a decrease in blood flow (a lack of PIV) was observed in some individuals. The patients tended to have higher interface pressure during pressure exposure than the healthy groups but no differences in blood flow responses were seen. Our results showed that pressure levels that are normally considered to be harmless could have a significant effect on the microcirculation in different tissue structures. Differences in individual blood flow responses in terms of PIV and RH were seen, and a larger proportion of individuals lacked these responses in the deeper tissue structures compared to more superficial tissue structures.This thesis identified PIV and RH that are important vascular mechanisms for pressure ulcer development and revealed for the first time that PIV and RH are present at different depths under clinically relevant conditions. The thesis also identified a population of individuals not previously identified who lack both PIV and RH and seem to be particularly vulnerable to pressure exposure. Further, this thesis has added a new perspective to the microcirculation in pressure ulcer etiology in terms of blood flow regulation and endothelial function that are anchored in clinically relevant studies. Finally, the evaluation of pressureredistribution support surfaces in terms of mean blood flow during and after tissue exposure was shown to be unfeasible, but the assessment of PIV and RH could provide a new possibility for measuring individual physiological responses that are known to be related to pressure ulcer development.
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