Assessing safety of negative-pressure wound therapy over pedicled muscle flaps: A retrospective review of gastrocnemius muscle flap

Accepted Manuscript Assessing Safety of Negative Pressure Wound Therapy over Pedicled Muscle Flaps: A Retrospective Review of Gastrocnemius Muscle Flap Samuel Lance, M.D., Lindsey Harrison, B.S., Hakan Orbay, M.D., Ph.D., David Boudreault, M.D., Gavin Pereira, MBBS, David Sahar, M.D. PII:

S1748-6815(15)00556-2

DOI:

10.1016/j.bjps.2015.11.010

Reference:

PRAS 4830

To appear in:

Journal of Plastic, Reconstructive & Aesthetic Surgery

Received Date: 23 September 2015 Revised Date:

10 November 2015

Accepted Date: 15 November 2015

Please cite this article as: Lance S, Harrison L, Orbay H, Boudreault D, Pereira G, Sahar D, Assessing Safety of Negative Pressure Wound Therapy over Pedicled Muscle Flaps: A Retrospective Review of Gastrocnemius Muscle Flap, British Journal of Plastic Surgery (2015), doi: 10.1016/j.bjps.2015.11.010. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Summary The use of negative pressure wound therapy for management of open wounds and immobilization of split-thickness skin grafts over wounds has been well described. However,

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there is a concern for potential compromise of flap viability when negative pressure wound therapy is used for skin grafts over pedicled muscle flaps. We have used negative pressure wound therapy to immobilize split-thickness skin grafts in eight patients who underwent a

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pedicled gastrocnemius muscle flap operation in our department. We applied a negative pressure of -75 mmHg on the muscle flaps for 5 days postoperatively. All wounds healed successfully,

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with a 97.5±5.5 % mean split-thickness skin graft uptake. No flap necrosis was observed. In our series, the use of negative pressure wound therapy for fixation of split-thickness skin grafts over pedicled gastrocnemius muscle flap was effective and had no negative impact on flap viability.

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Key words: negative pressure wound therapy · vacuum-assisted closure · gastrocnemius pedicled

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muscle flap · split thickness skin graft

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Assessing Safety of Negative Pressure Wound Therapy over Pedicled Muscle Flaps: A Retrospective Review of Gastrocnemius Muscle Flap Samuel Lance M.D.* 1, Lindsey Harrison B.S.* 1, Hakan Orbay M.D., Ph.D. 1, David Boudreault

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M.D. 1, Gavin Pereira, MBBS2, David Sahar M.D. 1 * These authors contributed equally to this work 1

Department of Surgery, Division of Plastic Surgery, University of California - Davis, CA,

Department of Orthopedic Surgery, University of California - Davis, CA, USA

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USA.

Running Head: Negative Pressure Wound Therapy over Muscle Flaps

This work should be attributed to:

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University of California Davis Medical Center. Department of Surgery, Division of Plastic Surgery. Cypress Building. 2221 Stockton Blvd., Suite E. Sacramento, CA 95817 USA

David E. Sahar, MD

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Corresponding Author:

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University of California Davis Medical Center. Department of Surgery, Division of Plastic Surgery. 2221 Stockton Boulevard, Suite 2123. Sacramento, CA 95817 Tel: 916-734-4834, Fax: 916-734-7104 E-mail: [email protected]

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Introduction Injuries of the lower limb often cause extensive soft tissue damage, which can be difficult to cover due to the diminished local blood flow.1 Medial and lateral gastrocnemius flaps provide

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reliable soft tissue coverage for the defects in the proximal third of the lower leg and increase vascularization when placed over the site of injury. 1, 2 Split thickness skin grafts (STSG) are

used to cover the raw surface of muscle flaps as primary closure over the flap is generally not

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possible. Negative pressure wound therapy (NPWT) is widely used in wound care to promote

healing of open wounds and STSG as a bolster while reducing tissue edema and bacterial counts. Despite the popularity of NPWT in wound treatment, there is a scarcity of publications

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examining the effectiveness of NPWT when used over STSG covering pedicled muscle flaps. The main concern is the potential for distal flap necrosis due to surface pressure induced by NPWT.

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The purpose of this study is to evaluate the safety of NPWT when used in conjunction with the pedicled gastrocnemius muscle flap to secure the STSG over the muscle flap. We hypothesize that NPWT placed over skin-grafted gastrocnemius muscle flaps will not

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compromise muscle viability. The authors adhered to the STROBE guidelines during the preparation of this manuscript.

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Patients and Methods

Between January 2011 and October 2013, we applied NPWT to the STSG of eight patients who underwent pedicle gastrocnemius flap operation. Out of all study patients, seven had medial and one had a lateral gastrocnemius flap and all operations were performed by a single full time academic surgeon. Detailed information about the patients can be found in Table 1. The gastrocnemius muscle flap was elevated and rotated on the defect zone using standard

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surgical technique as described elsewhere. The flap donor site was closed primarily over a 15F round Blake drain. The muscle flap was covered with 12/1000 inch thick STSG’s meshed 1:1. The STSG was secured with simple, running 5-0 chromic gut sutures. A V.A.C. therapy unit

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(KCI, San Antonio) was used to apply continuous negative pressure of -75 mmHg on the STSG for 5 days after operation. Meanwhile, the patients kept on strict bed rest with minimal activity. Patients were discharged on post-operative day 5 upon completion of NPWT.

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Mean patient age was 54.13 ± 6.9 years and mean graft area was 57 ± 32.6 cm2. Postoperative outcomes were evaluated for graft adherence and flap failure. Complete graft

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adherence and reduction in flap edema were observed in each case, without evidence of flap vascular compromise in the form of congestion or necrosis. Post-operative follow-up period ranged from 6 weeks to 8 months with no evidence of skin graft detachment (mean uptake = 97.5 ± 5.5 %) or flap compromise (Table 1).

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Case 1

A 56-year old female with no known comorbidities presented with a right proximal-third lower extremity wound with exposed tibia (Fig. 1). This defect was covered with a medial

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gastrocnemius flap followed by a STSG. The wound to be grafted measured 32cm2. The patient

noted. Case 2

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had 100 % graft adherence at 5 days and at 6 months follow-up. There were no complications

A 50-year old male with hypertension and diabetes mellitus underwent right total knee arthroplasty, resulting in a defect and draining wound (Fig. 2). The defect was covered with a medial gastrocnemius flap and STSG. Approximate graft area was 90cm2. The patient had 100% graft adherence at 5 days and on follow-up. There were no complications noted.

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Discussion NPWT became widely used since its introduction and changed the treatment algorithm for open wounds. However, the mechanism of action of NPWT remains controversial. A

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common theory is that NPWT decreases tissue pressure, resulting in dilation of capillaries, 5, 6

decrease in tissue edema, induction of angiogenesis and, ultimately, an accelerated and increased production of granulation tissue. 7-9 In contrary to this theory, it was shown that tissue pressure

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increases directly proportional to the magnitude of negative pressure applied, and may reach to a

NPWT on tissues prone to ischemia.

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point of compromise blood circulation. 10-12 Therefore, caution is recommended when using

The currently recommended magnitude of negative pressure to be used for NPWT is based on an experimental animal study by Morykwas et al. 3 In this study, Morykwas et al. investigated the effects of various levels of negative pressure on tissue perfusion in open

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standardized wounds in a swine model and concluded that blood flow could be increased 4-fold in comparison with baseline values when a pressure of -125 mmHg was applied. Following studies experimented with different magnitudes of negative pressure on different tissues in an

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attempt to find the optimum pressure that will not compromise the circulation, but at the same time preserve the beneficial effects of NPWT. Negative pressures ranging from 50-75 mmHg

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have been used on STSGs and pressure ulcers. A negative pressure within this range allowed uniform application of pressure to STSGs and at the same time minimized shear forces that may have impaired adhesion and vascularization of the graft. 7 Also in a porcine sternotomy wound model, the peak increase in blood flow was observed at -75 and -100 mmHg, while high pressures induced hypoperfusion. 5 Beneficial effects of NPWT were also observed at pressure levels as low as -45 mmHg. 13

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Considering all these studies and in order to minimize the risk of flap compromise in our series, we chose to use a negative pressure of -75 mmHg, which is less than the current standard pressure applied on open wounds (-125 mmHg). At this lower negative pressure, we observed

obtain an excellent STSG adherence, and decreased tissue edema.

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that the flaps remained viable and no detrimental effects were noted. Moreover, we could still

There no papers reporting necrosis of the muscle flaps with the application of NPWT.

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However, due to the concerns about flap compromise based on previous studies 10-12 only a small number of clinical studies have investigated the use of NPWT on skin-grafted muscle flaps. 14-18

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Eisenhardt et al., examined the use of NPWT over skin-grafted free flaps, and found that although the NPWT mildly compressed the muscle tissue, the underlying anastomosis and flap remained uncompromised. 15 In another study, Vaienti et al., reported that NPWT does not compromise free flap circulation. Rather, it resolves any venous insufficiency and necrosis of the

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flap, while stimulating production of viable granulation tissue. 18 Similar results have been reported by Hanasono et al., and Uygur et al. 14, 17

In contrast to previous reports focusing on free flaps, our series is focused solely on the

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use of NPWT on the gastrocnemius muscle flaps. Based on our experiences, we believe the type of vascular compromise may also affect the decision whether to use NPWT on muscle flaps or

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not. In case of a venous congestion NPWT might be helpful by draining the blood collected in the flap; however, in case of an arterial insufficiency NPWT may further compromise the circulation by increasing the tissue interstitial pressures and subsequently vascular resistance. In such cases, we recommend the use of decreased negative pressure levels. As clearly demonstrated by our results and others, NPWT has beneficial effects on tissues even at lower magnitudes of negative pressure. As a precaution, NPWT should not be applied circumferentially

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on the rotational muscle flaps. Mean tissue pressure increments resulting from the circumferential dressings were found to be significantly higher than those resulting from the noncircumferential dressings. 10 Therefore, circumferential NPWT dressings and high levels of

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negative pressure increase the risk of circulatory compromise in rotational muscle flaps and should be avoided.

In conclusion, the use of NPWT as a bolster for STSG on muscle flaps is effective and

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has no negative impact on flap viability when negative pressure is set at -75mmHg. The use of the NPWT allows for improved graft apposition and contouring over significant irregularities

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and decreases sheering. However, we recommend avoiding the use of circumferential and / or high pressure NPWT on rotational muscle flaps.

Conflict of Interest Statement

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The authors have no conflicts of interest to declare.

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References 1. Reddy V, Stevenson TR. MOC-PS(SM) CME article: lower extremity reconstruction. Plast Reconstr Surg 2008;121;1-7.

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2. Guzman-Stein G, Fix RJ, Vasconez LO. Muscle flap coverage for the lower extremity. Clin Plast Surg 1991;18;545-52.

3. Morykwas MJ, Argenta LC, Shelton-Brown EI, McGuirt W. Vacuum-assisted closure: a new

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method for wound control and treatment: animal studies and basic foundation. Ann Plast Surg 1997 Jun;38(6);553-62.

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4. Kanakaris NK, Thanasas C, Keramaris N, Kontakis G, Granick MS, Giannoudis PV. The efficacy of negative pressure wound therapy in lower extremity trauma: a review of clinical evidence. Injury 2007;38-S5;S9-S18.

5. Petzina R, Gustafsson L, Mokhtari A, Ingemansson R, Malmsjo M. Effect of vacuum-assisted

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closure on blood flow in the peristernal thoracic wall after internal mammary artery harvesting. Eur J Cardiothorac Surg 2006;30;85-9.

6. Chen SZ, Li J, Li XY, Xu LS. Effects of vacuum-assisted closure on wound microcirculation:

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an experimental study. Asian J Surg 2005;28;211-7.

7. Argenta LC, Morykwas MJ. Vacuum-assisted closure: a new method for wound control and

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treatment: clinical experience. Ann Plast Surg 1997;38;563-76; discussion 77. 8. Mendonca DA, Papini R, Price PE. Negative-pressure wound therapy: a snapshot of the evidence. Int Wound J 2006;3;261-71. 9. 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;66571.

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10. Kairinos N, Solomons M, Hudson DA. Negative-pressure wound therapy I: the paradox of negative-pressure wound therapy. Plast Reconstr Surg 2009;123;589-98; discussion 99-600.

vitro studies. J Plast Reconstr Aesthet Surg 2010;63;174-9.

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11. Kairinos N, Solomons M, Hudson DA. The paradox of negative pressure wound therapy--in

12. Kairinos N, Voogd AM, Botha PH, et al. Negative-pressure wound therapy II: negativepressure wound therapy and increased perfusion. Just an illusion? Plast Reconstr Surg

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2009;123;601-12.

13. Borgquist O, Ingemansson R, Malmsjö M. Wound edge microvascular blood flow during

Plast Reconstr Surg 2010 Feb;125(2);502-9

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negative-pressure wound therapy: examining the effects of pressures from -10 to -175 mmHg.

14. Hanasono MM, Skoracki R. Securing skin grafts to microvascular free flaps using the vacuum-assisted closure (VAC) device. Ann Plast Surg 2007 May;58(5);573-6.

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15. Eisenhardt SU, Schmidt Y, Thiele JR, et al. Negative pressure wound therapy reduces the ischaemia/reperfusion-associated inflammatory response in free muscle flaps. J Plast Reconstr Aesthet Surg 2012 May;65(5);640-9.

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16. Blackburn JH, 2nd, Boemi L, Hall WW, et al. Negative-pressure dressings as a bolster for skin grafts. Ann Plast Surg 1998;40;453-7.

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17. Uygur F, Duman H, Ulkur E, Celikoz B. The role of the vacuum-assisted closure therapy in the salvage of venous congestion of the free flap: case report. Int Wound J 2008;5(1);50–53. 18. Vaienti L, Gazzola R, Benanti E, et al. Failure by congestion of pedicled and free flaps for reconstruction of lower limbs after trauma: the role of negative-pressure wound therapy. J Orthop Traumatol 2013 Sep;14(3);213-7.

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Figure legends Figure 1. Figure shows the clinical course of case 1. (A) The defect before the operation; exposed bone can be seen at the wound base. (B) The defect was covered with a medial

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gastrocnemius flap. (C) The appearance of the flap at postoperative 6 months. (D) The

appearance of flap donor site at postoperative 6 months. (E) STSG donor site at postoperative 6 months.

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Figure 2. Figure shows the clinical course of case 2. (A) The defect on the knee was covered by a medial gastrocnemius flap. (B) The appearance of flap at postoperative 6 months. (C) The

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appearance of donor site at postoperative 6 months.

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Table 1. Study patients Pt 1

Side

Flap

Age

Sex

Comorbidities

1

R Knee

Medial

56

F

none

Injury/wound

Graft Area (cm2)

Duration of NPWT (days) 5

Immediate graft take (%) 100

Post-op followup graft take (%) 100

Flap necrosis/vascular congestion none

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Right proximal 32 third, tibial wound with exposed bone 2 L Knee Lateral 50 M DM 2, smoking, Left knee 32 5 100 100 none Hep C 3, CAD 4 exposed hardware 3 R Knee Medial 48 M none Right knee open 120 5 Lost to follow-up none joint Right knee 90 5 100 none 4 R Knee Medial 50 M HTN 5, DM draining wound, status post total knee arthroplasty 5 L Knee Medial 63 F HTN, DM, Chronic drainage 40 5 100 85 none smoking and inadequate coverage 6 L Knee Medial 48 M Smoking Hardware 64 5 98 none replacement and chronic drainage 7 L Knee Medial 52 M DM, CVA 6 Acquired left 48 5 100 100 none knee defect 8 R Knee Medial 66 M none Acquired right 30 5 well 100 none knee open adherent wound 1 Pt = Patients, 2 DM = Diabetes Mellitus, 3 Hep C = Hepatitis C, 4 CAD = Coronary Artery Disease, 5 HTN = Hypertension, 6 CVA = Cerebrovascular Accident

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