| 1. |
- Anesäter, Erik, et al.
(författare)
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The use of a rigid disc to protect exposed structures in wounds treated with negative pressure wound therapy: Effects on wound bed pressure and microvascular blood flow.
- 2012
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Ingår i: Wound Repair and Regeneration. - 1524-475X. ; 20:4, s. 611-616
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Tidskriftsartikel (refereegranskat)abstract
- There are increasing reports of deaths and serious complications associated with the use of negative pressure wound therapy (NPWT). Bleeding may occur in patients when NPWT is applied to a wound with exposed blood vessels or vascular grafts, possibly due to mechanical deformation and hypoperfusion of the vessel walls. Recent evidence suggests that using a rigid barrier disc to protect underlying tissue can prevent this mechanical deformation. The aim of this study was to examine the effect of rigid discs on the tissue exposed to negative pressure with regard to tissue pressure and microvascular blood flow. Peripheral wounds were created on the backs of eight pigs. The pressure and microvascular blood flow in the wound bed were measured when NPWT was applied. The wound was filled with foam, and rigid discs of different designs were inserted between the wound bed and the foam. The discs were created with or without channels (to accommodate exposed sensitive structures such as blood vessels and nerves), perforations, or a porous dressing that covered the underside of the discs (to facilitate pressure transduction and fluid evacuation). When comparing the results for pressure transduction to the wound bed, no significant differences were found using different discs covered with dressing, whereas pressure transduction was lower with bare discs. Microvascular blood flow in the wound bed decreased by 49 ± 7% when NPWT was applied to control wounds. The reduction in blood flow was less in the presence of a protective disc (e.g., -6 ± 5% for a dressing-covered, perforated disc, p = 0.006). In conclusion, NPWT causes hypoperfusion of superficial tissue in the wound bed. The insertion of a rigid barrier counteracts this effect. The placement of a rigid disc over exposed blood vessels or nerves may protect these structures from rupture and damage.
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| 2. |
- Borgquist, Ola, et al.
(författare)
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Measurements of wound edge microvascular blood flow during negative pressure wound therapy using thermodiffusion and transcutaneous and invasive laser Doppler velocimetry
- 2011
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Ingår i: Wound Repair and Regeneration. - 1524-475X. ; 19:6, s. 727-733
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Tidskriftsartikel (refereegranskat)abstract
- The effects of negative pressure wound therapy (NPWT) on wound edge microvascular blood flow are not clear. The aim of the present study was therefore to further elucidate the effects of NPWT on periwound blood flow in a porcine peripheral wound model using different blood flow measurement techniques. NPWT at -20, -40, -80, and -125 mmHg was applied to a peripheral porcine wound (n = 8). Thermodiffusion, transcutaneous, and invasive laser Doppler velocimetry were used to measure the blood perfusion 0.5, 1.0, and 2.5 cm from the wound edge. Thermodiffusion (an invasive measurement technique) generally showed a decrease in perfusion close to the wound edge (0.5 cm), and an increase further from the edge (2.5 cm). Invasive laser Doppler velocimetry showed a similar response pattern, with a decrease in blood flow 0.5 cm from the wound edge and an increase further away. However, 1.0 cm from the wound edge blood flow decreased with high pressure levels and increased with low pressure levels. A different response pattern was seen with transcutaneous laser Doppler velocimetry, showing an increase in blood flow regardless of the distance from the wound edge (0.5, 1.0, and 2.5 cm). During NPWT, both increases and decreases in blood flow can be seen in the periwound tissue depending on the distance from the wound edge and the pressure level. The pattern of response depends partly on the measurement technique used. The combination of hypoperfusion and hyperperfusion caused by NPWT may accelerate wound healing.
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| 3. |
- Malmsjö, Malin, et al.
(författare)
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Negative-pressure wound therapy using gauze or open-cell polyurethane foam: similar early effects on pressure transduction and tissue contraction in an experimental porcine wound model.
- 2009
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Ingår i: Wound Repair and Regeneration. - 1524-475X. ; 17:2, s. 200-205
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Tidskriftsartikel (refereegranskat)abstract
- Negative-pressure wound therapy (NPWT), also known as topical negative-pressure therapy, is widely used to manage wounds and accelerate healing. NPWT has so far been delivered mainly via open-cell polyurethane foam, but increasing interest has been directed toward delivering NPWT via gauze. In the present study, the early effects of NPWT on pressure transduction and wound contraction were examined in wounds filled with either polyurethane foam or gauze. An experimental setup of a porcine wound model was used, in which the animals were anesthetized for 12-14 hours. Negative pressures between -50 and -175 mmHg were applied in -25 mmHg increments. Wound bed pressure was measured using a saline filled catheter sutured to the bottom of the wound. The contraction of the wound edges was also determined. The recordings were performed upon reaching steady state, which typically occurred within 1 minute. For both fillers, wound bed negative pressure increased linearly with delivered vacuum with little deviation from set pressure (correlation coefficient 0.99 in both cases). Similar tissue contraction was observed when using foam and gauze. The most prominent contraction was observed in the range of 0 to -50 mmHg with greater vacuum only producing minor further movement of the wound edge. In conclusion, the present experimental study shows that gauze and foam are equally effective at delivering negative pressure and creating mechanical deformation of the wound.
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| 4. |
- Velander, Patrik, et al.
(författare)
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Impaired wound healing in an acute diabetic pig model and the effects of local hyperglycemia.
- 2008
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Ingår i: Wound Repair and Regeneration. - 1524-475X. ; 16:2, s. 288-293
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Tidskriftsartikel (refereegranskat)abstract
- Diabetic wounds result in significant morbidity, prolonged hospitalization, and enormous health-care expenses. Pigs have been shown to have wound healing resembling that in humans. The aim of this study was to develop a large-animal model for diabetic wound healing. Diabetes was induced by streptozotocin injection in Yorkshire pigs. Full-thickness wounds were created and dressed with a sealed chamber. Nondiabetic pigs with or without high glucose wound fluid concentration served as controls. Glucose concentration in serum and wound fluid was measured and collected. Wound contraction was monitored, and biopsies were obtained for measurement of reepithelialization. Wound fluid was analyzed for insulin-like growth factor-1 (IGF-1), platelet-derived growth factor, and transforming growth factor. Glucose concentration in wound fluid initially followed serum levels and then decreased to undetectable on day 9. Reepithelialization was significantly delayed in diabetic pigs. In nondiabetic pigs, wounds treated in a local hyperglycemic environment, and thus excluding the effects of systemic hyperglycemia, showed no difference in wound closure compared with controls. This suggests that delayed wound healing in diabetes is not induced by local high-glucose concentration itself. Analysis of growth factor expression showed a marked reduction in IGF-1 in the diabetic wounds. Diabetic pigs have impaired healing that is accompanied by a reduction of IGF-1 in the healing wound and is not due to the local hyperglycemia condition itself.
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| 9. |
- Koskela, Anita, 1979-, et al.
(författare)
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Regulation of fibroblast gene expression by keratinocytes in organotypic skin culture provides possible mechanisms for the antifibrotic effect of reepithelialization
- 2010
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Ingår i: Wound Repair and Regeneration. - : The Wound Healing Society. - 1067-1927 .- 1524-475X. ; 18:5, s. 452-459
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the mechanisms behind the antifibrotic effect associated with epidermal regeneration, the expression of 12 fibroblast genes important for the modulation of the extracellular matrix (ECM), as well as alpha-smooth muscle actin, was studied in a keratinocyte-fibroblast organotypic skin culture model. The study was performed over time during epidermal generation and in the presence or absence of the profibrotic factor transforming growth factor-beta. the Presence of epidermal differentiation markers in the model was essentially coherent with that of native skin. Fibroblast gene expression was analyzed with real-time polymerase chain reaction after removal of the epidermal layer. After 2 days of air-exposed culture, 11 out of the 13 genes studied were significantly regulated by keratinocytes in the absence or presence of transforming growth factor-beta. The regulation of connective tissue growth factor, collagen I and III, fibronectin, plasmin system regulators, matrix metalloproteinases and their inhibitors as well as alpha-smooth muscle actin was consistent with a suppression of ECM formation or contraction. Overall, the results support a view that keratinocytes regulate fibroblasts to act catabolically on the ECM in epithelialization processes. This provides possible mechanisms for the clinical observations that reepithelialization and epidermal wound coverage counteract excessive scar formation.
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| 10. |
- Liu, Yawei, 1967-, et al.
(författare)
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Fibroblast proliferation due to exposure to a platelet concentrate in vitro is pH dependent
- 2002
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Ingår i: Wound Repair and Regeneration. - 1067-1927 .- 1524-475X. ; 10:5, s. 336-340
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Tidskriftsartikel (refereegranskat)abstract
- The influence of platelet-rich plasma lysates on fibroblast proliferation was studied in culture. Cells were exposed to platelet lysates that had been preincubated at different pHs (5.0, 7.1, and 7.6). Proliferation was evaluated with the MTT assay and incorporation of [3H]thymidine into macromolecules, while type I collagen production was assayed by Western blotting. Enzyme-linked immunosorbent assays were used to determine platelet-derived growth factor and transforming growth factor-β concentrations. Platelets preincubated in an acidic environment (pH 5.0) induced the highest degree of fibroblast proliferation, and the concentration of platelet-derived growth factor in the different treated lysates was the highest at that particular pH. The concentration of transforming growth factor-β, however, was lower after incubation at pH 5.0 than at either pH 7.1 or 7.6. These findings may be relevant to normal wound healing in vivo and useful in the treatment of wounds and delayed healing processes.
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