Management of Skin Grafts Using Negative Pressure Therapy: The Effect of Varied Pressure on Skin Graft Incorporation
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Index: WOUNDS. 2013;25(4):89–93.
Abstract: Introduction. Optimal pressure settings have been suggested in the use of negative pressure wound therapy (NPWT) in wound dressings. When used as a bolster for skin grafting, an NPWT setting of 125 mm Hg was initially suggested, but not validated through studies. The objective of this study is to report findings on the effect of varied pressure settings on the incorporation of split thickness skin grafts when using an NPWT bolster. Methods. From 2007 to 2010, 48 inpatients underwent split thickness skin grafting using a negative pressure system as a bolster under the care of 2 surgeons at 2 academic institutions. Twenty-two patients were evaluated retrospectively who were treated using NPWT bolsters at 75 mm Hg and 125 mm Hg based on the surgeon’s discretion. Twenty-six patients were evaluated prospectively and were randomized to 50 mm Hg, 75 mm Hg, 100 mm Hg, and 125 mm Hg pressure settings. Graft incorporation was assessed at time of bolster removal, 2 weeks, and 4 weeks, per standard protocol. Results. At each assessment point, incorporation of each skin graft was > 95% in all study subjects, at all pressure settings. Conclusion. Whereas initially postulated to be 125 mm Hg, ideal pressure settings for NPWT, when used as a bolster for split thickness skin grafts, may be lower. This study suggests that pressures as low as 50 mm Hg can be tolerated without compromise of skin graft incorporation. Study findings were presented at the Plastic Surgery Research Council Meeting in San Francisco, CA in April of 2010.
Negative pressure wound therapy (NPWT) has revolutionized the management of open wounds by mechanisms of bacteria clearance, moisture elimination, edema reduction, and angiogenesis stimulation.1-4 Given these benefits, many surgeons have adopted the use of NPWT as a bolster dressing for split-thickness skin grafts (STSG) and full-thickness skin grafts. Studies have shown improved graft survival and epithelialization with NPWT bolster, as well as decreased numbers in repeat STSG procedures.5-8 Incorporation seems particularly improved in large or irregularly shaped wounds.9-10 Although studies have suggested optimal pressure settings for healing of open wounds,11-12 these settings may not be optimal when using NPWT dressing as a bolster. The purpose of this study is to see if NPWT bolsters will achieve optimal incorporation at pressures lower than the standard pressure of 125 mm Hg commonly used in open wounds.
Materials and Methods
All patients undergoing STSG who were treated by the 2 senior authors, Wirth and Evans, between 2007 and 2010, were considered for this study. Outpatients, patients for whom NPWT was contraindicated, and patients who declined participation were excluded. All pathologies and wound locations were included. Institutional Review Board approval was obtained at each participating institution (University of California at Irvine and Long Beach Memorial) prior to initiating the study. All prospective patients signed informed consent prior to participation.
Patients undergoing STSG with NPWT bolster prior to December 2008 were assessed by retrospective chart review. Patients after December 2008 were assessed prospectively and randomized to 4 treatment arms: 50 mm Hg, 75 mm Hg, 100 mm Hg, and 125 mm Hg. Randomization was determined by computer algorithm prior to patient enrollment. Thickness of STSG, method of fixation, and decision for meshing or “piecrusting” were left to the surgeon’s discretion.
A negative pressure wound therapy bolster using a vacuum-assisted closure device (V.A.C., Kinetic Concepts, Inc, San Antonio, TX) was used in all patients.