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The evolution of negative pressure wound therapy: negative pressure wound therapy with instillation Complex wounds pose a considerable burden to patients and the health-care system. The development of negative pressure wound therapy (NPWT) has revolutionised the treatment of these wounds. NPWT helps create a favourable wound healing environment by removing infectious material, decreasing oedema and promoting perfusion and granulation tissue formation. Additionally, NPWT has been reported to help reduce time to wound closure and length of hospital stay. Modifications of this foundation of wound care have added intermittent instillation with a dwell time to NPWT (NPWTi-d). This new system offers more comprehensive wound care through automated wound irrigation, allowing more control over the wound environment and the opportunity to deliver topical wound solutions directly to the affected tissues. A comparison between the two therapies, NPWT and NPWTi-d, is described, and two real-world applications of NPWTi-d are presented. Declaration of interest TW presented as a faculty member during the 2014 International Surgical Wound Forum (ISWF), an annual educational event sponsored by KCI, an Acelity company, held in 2014 in Edinburgh, Scotland. This article is part of a KCI-funded educational supplement based on 2014 ISWF faculty presentations about wound-care strategies using negative pressure wound therapy. Acelity assisted with the editorial review of the manuscript. TW also has a consultant agreement with KCI, an Aecilty company. Key words: negative pressure wound therapy with instillation, wound healing, dwell time, instillation therapy
T
he widespread use of negative pressure wound therapy (NPWT) has revolutionised the treatment of complex wounds. It helps create a favourable environment for wound healing through stimulating granulation tissue formation and perfusion, reduction in oedema, and removal of exudate and infectious material.1,2 NPWT effects may be due to the concept of macrostrain (contraction of the wound caused by contraction of the foam), and microstrain (stretch and straining of the cellular elements pulled into the foam), which has been reported to promote cellular proliferation.3–5 This review will focus on one form of NPWT (V.A.C. Therapy; KCI, an Acelity company, San Antonio, TX, USA) and its latest technology.
The systems NPWT is a system composed of a hydrophobic open-cell reticulated foam dressing that is placed into the wound and then covered by a semi-occlusive drape. A hole cut in the drape allows attachment of suction tubing to the dressing. The other end of the tubing is connected to a microprocessor-controlled pump that creates negative pressure in a continuous or intermittent fashion. The tubing has pressure-sensing channels that allow for measurement of pressure at the wound surface to help with pressure regulation. The latest form of NPWT technology, the V.A.C. Ulta Negative Pressure Wound Therapy System (KCI, an Acelity Company, San Antonio, TX, USA), is an integrated wound management system that can be used for both traditional
P r o c e e d i n g s o f t h e I n t e r n at i o n a l s u r g i c a l wo u n d f o r u m 2 0 1 4
Tom Wolvos, Msc, MD, FAC, Chief, General Surgery, Scottsdale Healthcare Osborn Medical Center, Scottsdale, Arizona, USA Email: twolvosmd@ scottsdalesurgical. com 15
Journal of Wound Care. Downloaded from magonlinelibrary.com by 206.214.006.110 on November 2, 2015. For personal use only. No other uses without permission. . All rights reserved. JWC_KCI_Supplement_18MarchTC.indd 15
20/03/2015 15:30
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NPWT and NPWT with automated intermittent instillation of topical wound solutions with a dwell time (NPWTi-d; V.A.C. VeraFlo Therapy, KCI, an Acelity company).6–8 NPWTi-d helps cleanse the wound by loosening contaminants, followed by the subsequent removal of these materials during the negative pressure phase. A significant improvement in this system is that the topical solution is delivered to the wound as a preset volume, compared with the gravity feed seen with the original system. A ‘fill assist tool’ also allows a clinician to determine visually an appropriate volume of topical wound solution to be instilled for the specific wound dressing.
simply using an intermittent therapy alone.12 The findings from the porcine model have been supported by a recent human clinical study in which NPWTi-d with normal saline was used in 131 wounds of various aetiologies seen in 131 patients at three different centres in France.13 Saline was instilled for 20 or 30 seconds with a dwell time of 10 minutes, followed by -125mmHg continuous negative pressure for 4–12 hours. The results of this study were a 98% closure rate after an average of 13 days of treatment. The investigators also observed increased granulation tissue formation and reduced wound volume.13
Continuous versus intermittent instillation systems
A list of wounds that are appropriate for adjunctive NPWTi‑d has been previously published.14 Typical wound types include: wounds with invasive infection, extensive contamination, stalled wounds, diabetic foot ulcers, and wounds with a very viscous exudate (Case study 1). NPWTi-d should not be used as the sole therapy for these wounds; it should be combined with a comprehensive programme that includes debridements, if indicated, and when appropriate, use of systemic antibiotics.15 NPWTi-d should not be used if topical solution will be instilled into the abdominal or thoracic cavities. Solutions should not be used if they will degrade the foam or other parts of the system. Since NPWTi-d is an intermittent mode, it should not be used in wounds where continuous negative pressure therapy is required, such as a bolster for skin grafts.
In another commercially available instillation system (Svedman Wound Treatment System; Innovative Therapies Inc., Hunt Valley, MD), the topical wound solution is instilled while the negative pressure is being applied (continuous instillation). With this type of system, when negative pressure is applied, tunnels may remain collapsed and areas of undermining and the edges of crevices may be pulled together; thus, these areas inside the wound would be inaccessible to the instilled solution. Conversely, during an intermittent system, when negative pressure is paused during the instillation and dwell phases, the inside of tunnels, crevices and areas of undermining are allowed to open up and are accessible to the instilled solution. In a bench top agarbased anatomic wound model, the solution was demonstrated to access areas of tunnelling in an intermittent instillation system (i.e. three 10-minute dwell times) while being inaccessible in a continuous instillation system (solution delivered continuously at a constant rate of 30ml/hour for 3.5 hours, with continuous removal by negative pressure).9
NPWTi-d and non-infected wounds There is in vitro evidence that instillation of normal saline alone may be more effective than traditional NPWT.10 In a non-infected full-thickness porcine wound model, instillation of normal saline every 6 hours resulted in wound fill with higher quality granulation tissue composed of increased collagen when compared with NPWT alone. The 43% increase in granulation tissue thickness after 7 days was statistically significant (p
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The evolution of negative pressure wound therapy: negative pressure wound therapy with instillation Complex wounds pose a considerable burden to patients and the health-care system. The development of negative pressure wound therapy (NPWT) has revolutionised the treatment of these wounds. NPWT helps create a favourable wound healing environment by removing infectious material, decreasing oedema and promoting perfusion and granulation tissue formation. Additionally, NPWT has been reported to help reduce time to wound closure and length of hospital stay. Modifications of this foundation of wound care have added intermittent instillation with a dwell time to NPWT (NPWTi-d). This new system offers more comprehensive wound care through automated wound irrigation, allowing more control over the wound environment and the opportunity to deliver topical wound solutions directly to the affected tissues. A comparison between the two therapies, NPWT and NPWTi-d, is described, and two real-world applications of NPWTi-d are presented. Declaration of interest TW presented as a faculty member during the 2014 International Surgical Wound Forum (ISWF), an annual educational event sponsored by KCI, an Acelity company, held in 2014 in Edinburgh, Scotland. This article is part of a KCI-funded educational supplement based on 2014 ISWF faculty presentations about wound-care strategies using negative pressure wound therapy. Acelity assisted with the editorial review of the manuscript. TW also has a consultant agreement with KCI, an Aecilty company. Key words: negative pressure wound therapy with instillation, wound healing, dwell time, instillation therapy
T
he widespread use of negative pressure wound therapy (NPWT) has revolutionised the treatment of complex wounds. It helps create a favourable environment for wound healing through stimulating granulation tissue formation and perfusion, reduction in oedema, and removal of exudate and infectious material.1,2 NPWT effects may be due to the concept of macrostrain (contraction of the wound caused by contraction of the foam), and microstrain (stretch and straining of the cellular elements pulled into the foam), which has been reported to promote cellular proliferation.3–5 This review will focus on one form of NPWT (V.A.C. Therapy; KCI, an Acelity company, San Antonio, TX, USA) and its latest technology.
The systems NPWT is a system composed of a hydrophobic open-cell reticulated foam dressing that is placed into the wound and then covered by a semi-occlusive drape. A hole cut in the drape allows attachment of suction tubing to the dressing. The other end of the tubing is connected to a microprocessor-controlled pump that creates negative pressure in a continuous or intermittent fashion. The tubing has pressure-sensing channels that allow for measurement of pressure at the wound surface to help with pressure regulation. The latest form of NPWT technology, the V.A.C. Ulta Negative Pressure Wound Therapy System (KCI, an Acelity Company, San Antonio, TX, USA), is an integrated wound management system that can be used for both traditional
P r o c e e d i n g s o f t h e I n t e r n at i o n a l s u r g i c a l wo u n d f o r u m 2 0 1 4
Tom Wolvos, Msc, MD, FAC, Chief, General Surgery, Scottsdale Healthcare Osborn Medical Center, Scottsdale, Arizona, USA Email: twolvosmd@ scottsdalesurgical. com 15
Journal of Wound Care. Downloaded from magonlinelibrary.com by 206.214.006.110 on November 2, 2015. For personal use only. No other uses without permission. . All rights reserved. JWC_KCI_Supplement_18MarchTC.indd 15
20/03/2015 15:30
supplement
NPWT and NPWT with automated intermittent instillation of topical wound solutions with a dwell time (NPWTi-d; V.A.C. VeraFlo Therapy, KCI, an Acelity company).6–8 NPWTi-d helps cleanse the wound by loosening contaminants, followed by the subsequent removal of these materials during the negative pressure phase. A significant improvement in this system is that the topical solution is delivered to the wound as a preset volume, compared with the gravity feed seen with the original system. A ‘fill assist tool’ also allows a clinician to determine visually an appropriate volume of topical wound solution to be instilled for the specific wound dressing.
simply using an intermittent therapy alone.12 The findings from the porcine model have been supported by a recent human clinical study in which NPWTi-d with normal saline was used in 131 wounds of various aetiologies seen in 131 patients at three different centres in France.13 Saline was instilled for 20 or 30 seconds with a dwell time of 10 minutes, followed by -125mmHg continuous negative pressure for 4–12 hours. The results of this study were a 98% closure rate after an average of 13 days of treatment. The investigators also observed increased granulation tissue formation and reduced wound volume.13
Continuous versus intermittent instillation systems
A list of wounds that are appropriate for adjunctive NPWTi‑d has been previously published.14 Typical wound types include: wounds with invasive infection, extensive contamination, stalled wounds, diabetic foot ulcers, and wounds with a very viscous exudate (Case study 1). NPWTi-d should not be used as the sole therapy for these wounds; it should be combined with a comprehensive programme that includes debridements, if indicated, and when appropriate, use of systemic antibiotics.15 NPWTi-d should not be used if topical solution will be instilled into the abdominal or thoracic cavities. Solutions should not be used if they will degrade the foam or other parts of the system. Since NPWTi-d is an intermittent mode, it should not be used in wounds where continuous negative pressure therapy is required, such as a bolster for skin grafts.
In another commercially available instillation system (Svedman Wound Treatment System; Innovative Therapies Inc., Hunt Valley, MD), the topical wound solution is instilled while the negative pressure is being applied (continuous instillation). With this type of system, when negative pressure is applied, tunnels may remain collapsed and areas of undermining and the edges of crevices may be pulled together; thus, these areas inside the wound would be inaccessible to the instilled solution. Conversely, during an intermittent system, when negative pressure is paused during the instillation and dwell phases, the inside of tunnels, crevices and areas of undermining are allowed to open up and are accessible to the instilled solution. In a bench top agarbased anatomic wound model, the solution was demonstrated to access areas of tunnelling in an intermittent instillation system (i.e. three 10-minute dwell times) while being inaccessible in a continuous instillation system (solution delivered continuously at a constant rate of 30ml/hour for 3.5 hours, with continuous removal by negative pressure).9
NPWTi-d and non-infected wounds There is in vitro evidence that instillation of normal saline alone may be more effective than traditional NPWT.10 In a non-infected full-thickness porcine wound model, instillation of normal saline every 6 hours resulted in wound fill with higher quality granulation tissue composed of increased collagen when compared with NPWT alone. The 43% increase in granulation tissue thickness after 7 days was statistically significant (p
