| 1. |
- Anesater, Erik, et al.
(författare)
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A Rigid Disc for Protection of Exposed Blood Vessels During Negative Pressure Wound Therapy
- 2013
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Ingår i: Surgical Innovation. - : SAGE Publications. - 1553-3506 .- 1553-3514. ; 20:1, s. 74-80
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Tidskriftsartikel (refereegranskat)abstract
- Background. There are increasing reports of serious complications and deaths associated with negative pressure wound therapy (NPWT). Bleeding may occur when NPWT is applied to a wound with exposed blood vessels. Inserting a rigid disc in the wound may protect these structures. The authors examined the effects of rigid discs on wound bed tissue pressure and blood flow through a large blood vessel in the wound bed during NPWT. Methods. Wounds were created over the femoral artery in the groin of 8 pigs. Rigid discs were inserted. Wound bed pressures and arterial blood flow were measured during NPWT. Results. Pressure transduction to the wound bed was similar for control wounds and wounds with discs. Blood flow through the femoral artery decreased in control wounds. When a disc was inserted, the blood flow was restored. Conclusions. NPWT causes hypoperfusion in the wound bed tissue, presumably as a result of mechanical deformation. The insertion of a rigid barrier alleviates this effect and restores blood flow.
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| 2. |
- Anesäter, Erik, et al.
(författare)
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The influence of different sizes and types of wound fillers on wound contraction and tissue pressure during negative pressure wound therapy.
- 2011
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Ingår i: International Wound Journal. - 1742-481X. ; 8, s. 336-342
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Tidskriftsartikel (refereegranskat)abstract
- Negative pressure wound therapy (NPWT) contracts the wound and alters the pressure in the tissue of the wound edge, which accelerates wound healing. The aim of this study was to examine the effect of the type (foam or gauze) and size (small or large) of wound filler for NPWT on wound contraction and tissue pressure. Negative pressures between -20 and -160 mmHg were applied to a peripheral porcine wound (n = 8). The pressure in the wound edge tissue was measured at distances of 0·1, 0·5, 1·0 and 2·0 cm from the wound edge and the wound diameter was determined. At 0·1 cm from the wound edge, the tissue pressure decreased when NPWT was applied, whereas at 0·5 cm it increased. Tissue pressure was not affected at 1·0 or 2·0 cm from the wound edge. The tissue pressure, at 0·5 cm from the wound edge, was greater when using a small foam than when using than a large foam. Wound contraction was greater when using a small foam than when using a large foam during NPWT. Gauze resulted in an intermediate wound contraction that was not affected by the size of the gauze filler. The use of a small foam to fill the wound causes considerable wound contraction and may thus be used when maximal mechanical stress and granulation tissue formation are desirable. Gauze or large amounts of foam result in less wound contraction which may be beneficial, for example when NPWT causes pain to the patient.
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| 3. |
- Anesäter, Erik, et al.
(författare)
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The influence on wound contraction and fluid evacuation of a rigid disc inserted to protect exposed organs during negative pressure wound therapy.
- 2011
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Ingår i: International Wound Journal. - 1742-481X. ; 8, s. 393-399
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Tidskriftsartikel (refereegranskat)abstract
- The use of a rigid disc as a barrier between the wound bed and the wound filler during negative pressure wound therapy (NPWT) has been suggested to prevent damage to exposed organs. However, it is important to determine that the effects of NPWT, such as wound contraction and fluid removal, are maintained during treatment despite the use of a barrier. This study was performed to examine the effect of NPWT on wound contraction and fluid evacuation in the presence of a rigid disc. Peripheral wounds were created on the backs of eight pigs. The wounds were filled with foam, and rigid discs of different designs were inserted between the wound bed and the foam. Wound contraction and fluid evacuation were measured after application of continuous NPWT at -80 mmHg. Wound contraction was similar in the presence and the absence of a rigid disc (84 ± 4% and 83 ± 3%, respectively, compared with baseline). Furthermore, the rigid disc did not affect wound fluid removal compared with ordinary NPWT (e.g. after 120 seconds, 71 ± 4 ml was removed in the presence and 73 ± 3 ml was removed in the absence of a disc). This study shows that a rigid barrier may be placed under the wound filler to protect exposed structures during NPWT without affecting wound contraction and fluid removal, which are two crucial features of NPWT.
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| 4. |
- 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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| 5. |
- Birke-Sorensen, H., et al.
(författare)
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Evidence-based recommendations for negative pressure wound therapy: Treatment variables (pressure levels, wound filler and contact layer) - Steps towards an international consensus
- 2011
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Ingår i: Journal of Plastic, Reconstructive and Aesthetic Surgery. - : Elsevier BV. - 1878-0539 .- 1748-6815. ; 64, s. 1-16
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Forskningsöversikt (refereegranskat)abstract
- Negative pressure wound therapy (NPWT) is becoming a commonplace treatment in many clinical settings. New devices and dressings are being introduced. Despite widespread adoption, there remains uncertainty regarding several aspects of NPWT use. To respond to these gaps, a global expert panel was convened to develop evidence-based recommendations describing the use of NPWT. In a previous communication, we have reviewed the evidence base for the use of NPWT within trauma and reconstructive surgery. In this communication, we present results of the assessment of evidence relating to the different NPWT treatment variables: different wound fillers (principally foam and gauze); when to use a wound contact layer; different pressure settings; and the impact of NPWT on bacterial bioburden. Evidence-based recommendations were obtained by a systematic review of the literature, grading of evidence and drafting of the recommendations by a global expert panel. Evidence and recommendations were graded according to the Scottish Intercollegiate Guidelines Network (SIGN) classification system. In general, there is relatively weak evidence on which to base recommendations for any one NPWT treatment variable over another. Overall, 14 recommendations were developed: five for the choice of wound filler and wound contact layer, four for choice of pressure setting and five for use of NPWT in infected wounds. With respect to bioburden, evidence suggests that reduction of bacteria in wounds is not a major mode of action of NPWT. (C) 2011 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.
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| 6. |
- Borgquist, Ola, et al.
(författare)
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Individualizing the Use of Negative Pressure Wound Therapy for Optimal Wound Healing: A Focused Review of the Literature
- 2011
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Ingår i: Ostomy - Wound Management. - 0889-5899. ; 57:4, s. 44-44
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Forskningsöversikt (refereegranskat)abstract
- Currently available research suggests that negative pressure wound therapy (NPWT) creates a moist wound healing environment, drains exudate, reduces tissue edema, contracts the wound edges, mechanically stimulates the wound bed, and influences blood perfusion at the wound edge, which may lead to angiogenesis and the formation of granulation tissue. Although no clear evidence is available that NPWT accelerates wound healing compared to other interventions or that one form of NPWT is better than another, preclinical research suggests that the most commonly used dressings, level of negative pressure, and application mode (continuous, intermittent, or variable) may not be optimal for all patients. To summarize available literature related to these NPWT choices, pertinent literature published between 2005 and 2010 was reviewed. Preclinical study results suggest that the maximal biological effect of NPWT at the wound edge often can be achieved at -80 mm Hg and that foam dressings may be advantageous for large defect wounds, whereas gauze dressings may be more suitable for smaller wounds or when scar formation or pain is a concern. Preclinical research results also suggest that intermittent or variable pressure application has a better effect on granulation tissue formation than continuous application. The variable pressure mode maintains a negative pressure environment at lower pressure settings without dramatic fluctuations inherent to intermittent (on-and-off) pressure. Prospective, controlled clinical studies are needed to compare NPWT to other advanced wound care protocols of care and to ascertain the effect of various NPWT methods and regimens on outcomes of care.
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| 7. |
- 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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| 8. |
- Borgquist, Ola, et al.
(författare)
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Micro- and macromechanical effects on the wound bed of negative pressure wound therapy using gauze and foam.
- 2010
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Ingår i: Annals of Plastic Surgery. - 1536-3708. ; 64:6, s. 789-793
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Tidskriftsartikel (refereegranskat)abstract
- Negative pressure wound therapy (NPWT) results in 2 types of tissue deformation, macrodeformation (ie, wound contraction) and microdeformation (ie, the interaction of tissue and dressing on a microscopic level). These effects have been delineated for one type of wound filler, foam, but not for gauze. The mechanical deformation initiates a signaling cascade which ultimately leads to wound healing. The aim of the present study was to examine the effect of gauze and foam on macro- and microdeformation during treatment with negative pressure. An in vivo porcine peripheral wound model was used. NPWT was applied for 72 hours at 0, -75, and -125 mm Hg, using either foam or gauze as wound filler. The mechanical effects of NPWT were examined by measuring the wound surface area reduction and by histologic analysis of the wound bed tissue. Similar degrees of wound contraction (macrodeformation) were seen during NPWT regardless if foam or gauze was used. After negative pressure had been discontinued, the wound stayed contracted. There was no difference in wound contraction between -75 and -125 mm Hg. Biopsies of the wound bed revealed a repeating pattern of wound surface undulations and small tissue blebs ("tissue mushrooms") were pulled into the pores of the foam dressing and the spaces between the threads in the gauze dressing (microdeformation). This pattern was obvious in wounds treated both with foam and gauze, at atmospheric pressure (0 mm Hg) as well as at subatmospheric pressures (-75 and -125 mm Hg). The degrees of micro- and macrodeformation of the wound bed are similar after NPWT regardless if foam or gauze is used as wound filler.
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| 9. |
- Borgquist, Ola, et al.
(författare)
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The Effect of Intermittent and Variable Negative Pressure Wound Therapy on Wound Edge Microvascular Blood Flow
- 2010
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Ingår i: Ostomy - Wound Management. - 0889-5899. ; 56:3, s. 60-67
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Tidskriftsartikel (refereegranskat)abstract
- Negative pressure wound therapy (NPWT) alters wound edge microvascular blood flow. Some preclinical data suggest that cycling between low and high negative pressure may be more beneficial than continuous NPWT. The purpose of this in vivo study was to compare the effect of intermittent negative pressure (cycled either from 0 to -75 or to -125 mm Hg) and variable negative pressure (cycled from -10 to -75 or -125 mm Hg or from -45 to -75 or -125 mm Hg) on wound edge microvascular blood flow. Using a peripheral wound model (n = 8 domestic 70-kg pigs), intermittent and variable NPWT was applied to surgically created wounds (5 cm diameter, 2 cm. depth) for five cycles of 5 minutes of high and 2 minutes of low pressure. Blood flow was measured using laser Doppler velocimetry in subcutaneous and muscle tissue at 0.5 and 2.5 cm from the wound edge. When NPWT was applied, blood flow decreased an average of 29% +/- 2% in muscle tissue and 22 % +/- 4% in subcutaneous tissue at -75 mm Hg at 0.5 cm from the wound edge and increased an average of 20% +/- 6% for -75 mm Hg at 2.5 cm from the wound edge. Blood flow changed repeatedly when negative pressure was cycled. Large gradients between the cycled pressures (eg, -10 to -75 mm Hg) resulted in greater blood flow alterations than smaller (eg, -45 to -75 mm Hg) gradients. Blood flow alternations were similar between low-pressure settings of -10 mm Hg (variable NPWT) and 0 mm Hg (intermittent NPWT) and between high-pressure settings of -75 or -125 mm Hg. Both intermittent and variable NPWT result in a beneficial combination of increased blood flow, known to facilitate oxygenation and nutrient supply, and decreased blood flow, known to stimulate angiogenesis and granulation tissue formation. Cycling the negative pressure may be especially advantageous when treating poorly vascularized tissue. In cases where intermittent therapy causes patient discomfort, variable therapy may be superior.
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| 10. |
- Borgquist, Ola, et al.
(författare)
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The influence of low and high pressure levels during negative pressure wound therapy on wound contraction and fluid evacuation.
- 2011
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Ingår i: Plastic and Reconstructive Surgery. - 0032-1052. ; 127:2, s. 551-559
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Negative pressure wound therapy (NPWT) promotes healing by drainage of excessive fluid and debris and also by mechanical deformation of the wound edge tissue. The most commonly used negative pressure is -125 mmHg. However, this pressure may cause pain and ischemia, and the pressure often needs to be reduced. The aim of the present study was to examine wound contraction and fluid removal during low and increasing levels of negative pressures. METHODS: A peripheral wound was created in 70 kg pigs. The immediate effects of NPWT (-10 to -175 mmHg) on wound contraction and fluid removal was studied in eight pigs. The long-term effects on wound contraction were studied in eight additional pigs during 72 hours of NPWT at -75 mmHg. RESULTS: The wound contraction and fluid removal increased gradually with increasing levels of negative pressure until reaching a steady state. Maximum wound contraction was observed at -75 mmHg. When NPWT was discontinued, after 72 hours of therapy, the wound surface area was smaller than before therapy. Maximum wound fluid removal was observed at -125 mmHg. Higher pressures did not further reduce wound surface area or fluid volume. The time required for evacuation of 50% of the maximal fluid drained for a specific pressure level was longer for low negative pressures (∼45 s for pressures below -50 mmHg) than for high negative pressures (∼15-20 s for pressures above -50 mmHg). CONCLUSIONS: NPWT facilitates drainage of wound fluid and exudates and results in mechanical deformation of the wound edge tissue which is known to stimulate granulation tissue formation. Maximum wound contraction is achieved already at -75 mmHg, and this may be a suitable pressure for most wounds. In wounds with large volumes of exudate, higher pressure levels may be needed for the initial treatment period.
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