Original research
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Management of Skin Grafts Using
Negative Pressure Therapy: The Effect
of Varied Pressure on Skin Graft
Incorporation
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Address correspondence to:
Maristella Evangelista
Aesthetic and Plastic Surgery
Institute
University of California at Irvine
200 South Manchester Avenue,
Suite 650
Orange, CA 92648
[email protected]
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From the Aesthetic and Plastic
Surgery Institute, University of
California Irvine, Orange, CA and
Long Beach Memorial Medical
Center, Long Beach, CA
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.
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WOUNDS 2013;25(4):89–93
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Maristella S. Evangelista, MD, MBA; Eugene K. Kim, MD;
Gregory R. D. Evans, MD, FACS; Garrett A.Wirth, MD, MS, FACS
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egative 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 bolVol. 25, No. 4 April 2013
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Evangelista et al
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sters will achieve optimal incorporation at pressures lower than the standard pressure of 125 mm Hg commonly
used in open wounds.
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Figure 1. Patient distribution across varied negative pressure wound therapy settings.
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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. The bolster
was applied with a single layer petrolatum gauze interface between the STSG and the NPWT dressing. Length
of time with NPWT dressing was left to the surgeons’ discretion, but was primarily based on maximum reduction
of fluid exudate. Epithelialization was visually estimated
as a percent of incorporation by attending surgeons and
resident surgeons at time of bolster removal, at 2 weeks,
and at 4 weeks. Pictures were taken at each visit and findings were recorded.
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Materials and Methods
Keypoints
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atients 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 treatments 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.
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Figure 2. Average wound size at varied negative pressure
wound therapy settings.
Results
Forty-eight patients, 32 males and 16 females, were included in the study.Average age was 49 (range 13-89).The
retrospective pool contained 22 patients, with 3 patients
in the 75 mm Hg group and 19 patients in the 125 mm
Hg group. The prospective pool contained 26 patients,
with 2, 8, 4, and 12 patients in 50 mm Hg, 75 mm Hg,
100 mm Hg, and 125 mm Hg groups, respectively. Given
similar demographic and wound profiles, retrospective
and prospective data were pooled for assessment. Statistical significance was not calculated due to the small study
population.
Across all patients, average number of comorbidities
was 1 (range 0-5).Average wound size was 151 cm2 (range
28 cm2 - 561 cm2 ). Most common pathologies were trauma, 44%; oncology, 23%; and infection, 12.5%. The negative pressure wound therapy bolster was kept in place for
an average of 5 days (range 3 days - 8 days). Estimation of
skin graft incorporation was > 95% in all patients and at
Evangelista et al
Table 1. Summary of demographic data and comorbidities in various pressure groups.
75 mm Hg
100 mm Hg
2
11
4
71
53
53
Percentage female
50%
36%
0%
Average wound size
70
171
125
Percentage smokers
0%
18%
25%
13%
Percentage diabetes
mellitus
0%
9%
0%
6%
100%
0%
0%
10%
98%
Percentage take at 2
weeks
98%
Percentage take at 6
weeks
100%
31
46
35%
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167
98%
98%
95%
98%
100%
95%
100%
98%
100%
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Percentage take at 0
weeks
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Percentage myocardial
infarction, cerebrovascular accident or
stroke, or peripheral
vascular disease
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Average age
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Number of patients
125 mm Hg
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50 mm Hg
Figure 4. Postoperative results of skin grafting with negative pressure bolster at 50 mm Hg on postoperative day 5,
at time of bolster removal.
all time points.Across all patients, average wound size was
70 cm2, 171 cm2, 125 cm2, and 167 cm2, in the 50 mm Hg,
75 mm Hg, 100 mm Hg, and 125 mm Hg groups, respectively. The distribution of patients and wound size across
these pressure settings is summarized in Figure 1 and Figure 2. A summary of demographic data and comorbidities
associated with these groups is shown in Table 1.
No significant complications were encountered in the
study. One patient was treated with 3 skin grafts at nearby
sites on the lower extremity after the patient suffered compartment syndrome on the right lower extremity. In this
patient, each surgery was > 1 year apart and due to new
open wounds related to comorbidities of diabetes, peripheral vascular disease, and collagen disorder. This patient
had a pressure setting of 125 mm Hg on his NPWT bolster.
A second patient showed evidence of hypertrophic
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Figure 3. Hypertrophic scarring in a postradiation wound
after skin grafting with negative pressure bolster dressing
at 50 mm Hg.
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Evangelista et al
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Figure 5. (A) Preoperative and (B) postoperative results after skin grafting with negative pressure bolster at 75 mm Hg.
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and Figure 6 show results of other patients
at the various pressure settings.
Discussion
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Negative pressure
wound therapy is an
established
option
in the bolstering of
STSG.5-8 It seems to
offer particular benFigure 6. (A) Preoperative and (B) postoperative results after
efits in large and irskin grafting with negative pressure bolster at 125 mm Hg.
regularly contoured
wounds.9-11 In their
scarring at the STSG site after treatment with NPWT at clinical practice, senior authors Wirth and Evans have
50 mm Hg. This was thought to be related to prior ra- found that pressure settings of 125 mm Hg are not necdiation therapy to the wound bed. Figure 3 shows the essary to achieve good skin graft epithelialization. This
results on skin grafting in this patient. Figure 4, Figure 5, observation prompted review and further study of data,
the findings of which suggest that pressure settings as
low as 50 mm Hg can be used without compromise to
Keypoints
STSG incorporation.
• Across all patients, average number of comorbidities
2
Lower pressure settings may create potential benefits
was 1 (range 0-5). Average wound size was 151 cm
(range 28 cm2 - 561 cm2).
to patients and providers. The authors have noticed less
•Most common pathologies were trauma, 44%; onpain and less secondary skin reaction at the STSG cucology, 23%; and infection, 12.5%. The negative
taneous borders when lower pressure is used. Surgical
pressure wound therapy bolster was kept in place
concerns of venous occlusion and nerve compression,
for an average of 5 days (range 3 days - 8 days).
particularly in the pediatric population, may be obviat•Estimation of skin graft incorporation was > 95% in
ed. These findings follow the physiologic rationale that
all patients and at all time points.
any pressure above normal capillary pressure, approxi•No significant complications were encountered in
mately 25 mm Hg, should improve angiogenesis and epithe study.
thelialization.
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Evangelista et al
Limitations
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This study is limited in its population size and subjective measurements. The 50 mm Hg group, for instance,
had only 2 patients and wound sizes were smaller than
in other groups.These factors make it difficult to exclude
other reasons for successful take of the skin graft. Measuring endpoints by visual estimation also creates some
inaccuracy in this study’s results. Further analysis with
computer-based estimation, or histologic analysis, may
help to validate results. Finally, the benefit of NPWT at
lower pressure settings and in smaller wounds is not
clearly superior to that of a traditional bolster, and may
represent a higher cost that is not clearly beneficial to
patients. Further study in larger patient populations with
larger wound sizes will be necessary.
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• In their clinical practice, senior authors Wirth and
Evans have found that pressure settings of 125 mm
Hg are not necessary to achieve good skin graft epithelialization. This observation prompted review and
further study of data, the findings of which suggest
that pressure settings as low as 50 mm Hg can be
used without compromise to split thickness skin
graft incorporation.
Wound edge microvascular blood flow: effects of negative pressure wound therapy using gauze or polyurethane
foam. Ann Plast Surg. 2009;63(6):676-681.
Landau AG, Hudson DA, Adams K, Geldenhuys S, Pienaar
C. Full-thickness skin grafts: maximizing graft take using
negative pressure dressings to prepare the graft bed. Ann
Plast Surg. 2008;60(6):661-666.
Blackburn JH 2nd, Boemi L, Hall WW, et al. Negative-pressure dressings as a bolster for skin grafts. Ann Plast Surg.
1998;40(5):453-457.
Scherer LA, Shiver S, Chang M, Meredith JW, Owings JT.
The vacuum assisted closure device: a method of securing skin grafts and improving graft survival. Arch Surg.
2002;137(8):930-934.
Moisidis E, Heath T, Boorer C, Ho K, Deva AK. A prospective, blinded, randomized, controlled clinical trial of topical negative pressure use in skin grafting. Plast Reconstr
Surg. 2004;114(4):917-922.
Kim EK, Hong JP. Efficacy of negative pressure therapy to
enhance take of 1-stage allodermis and a split-thickness
graft. Ann Plast Surg. 2007;58(5):536-540.
Schneider AM, Morykwas MJ, Argenta LC. A new and reliable method of securing skin grafts to the difficult recipient bed. Plast Reconstr Surg. 1998;102(4):1195–1198.
Kasukurthi R, Borschel GH. Simplified Negative pressure
wound therapy in pediatric hand wounds. Hand (NY).
2010;5(1):95-98.
Morykwas MJ, Faler BJ, Pearce DJ, Argenta LC. Effects of
varying levels of subatmospheric pressure on the rate of
granulation tissue formation in experimental wounds in
swine. Ann Plast Surg. 2001;47(5):547-551.
Timmers MS, Le Cessie S, Banwell P, Jukema GN. The effects of varying degrees of pressure delivered by negative-pressure wound therapy on skin perfusion. Ann Plast
Surg. 2005;55(6):665-671.
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Keypoints
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Conclusions
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Negative pressure wound therapy offers established
benefits to STSG epithelialization.The findings in this study
suggest that pressure settings as low as 50 mm Hg may be
tolerated without compromise to epithelialization. Given
there are few patients and data points at this time, the
observations outlined serve as a proof of concept rather
than concrete clinical evidence. Further studies, in larger
study populations, larger wounds, wider spectra of pressure settings, and with more objective microscopic and
macroscopic measurement tools, are needed for better
understanding of the effect of pressure on epithelialization.
10.
Reference
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Argenta LC, Morykwas MJ.Vacuum-assisted closure: a new
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