Silver Dressings and Wound Healing

Weeping spots, lymphorrhea, Cuts, Scrapes, Stitches, Blisters, Silver Dressings, Compression therapy, wound bandaging, wound infections

Moderators: jenjay, Cassie, patoco, Birdwatcher, Senior Moderators

Silver Dressings and Wound Healing

Postby patoco » Wed Nov 08, 2006 9:27 am

Healing Chronic Infected Foot Wounds with Human Fibroblast-Derived Dermal Substitute and Silver Dressings

- Stanley N. Carson, MD, FACS; Alanna Pankovich, DPM; Eric Travis, DPM; Diana To, MPT; Angie Rodriguez, PT

Abstract: Thirty consecutive patients with diabetes, ischemia, and chronic wounds of the lower leg, ankle, and foot were treated over an 18-month period. Patients had appropriate moist wound care, and their wounds failed to heal for 5 weeks or more (average = 11 weeks, range 5–60 weeks). All patients were considered candidates for limb salvage and were referred for a final effort to avoid amputation. Based on previous experiences in the authors’ wound care program, wounds were treated with debridement, silver-coated cloth dressings, and a dermal substitute. All wounds were colonized with methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococcus (VRE), or a combination of MRSA and another organism, usually pseudomonas or a streptococcus species. All cultures from the episodes of cellulitis were positive for VRE, MRSA, or both, and these were the suspected infecting organisms. All patients gave informed consent for their procedures and wound care. All patients’ wounds were located in ischemic areas determined by toe pressures of 35–50 mmHg and ankle brachial indices. Ischemia was corrected as much as possible in all patients, and 20 patients received bypass or angioplasty for their lower-extremity ischemia. Seventeen patients progressed to satisfactory healing and spontaneous closure by 84 days (average 46 days, range 32–94 days). Eight patients required skin grafts, which healed. All patients had ankle brachial indices recorded, and none of the patients were categorized into the incompressible group. Five patients did not heal and required amputation. Debridement, silver-coated cloth dressings, and dermal substitute appear to be efficacious in healing diabetic, ischemic, lower-extremity chronic wounds.

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Diabetic lower-extremity ulcers are associated with significant morbidity and mortality. Although recent outcomes in the treatment of diabetic lower-extremity ulcers seem to trend toward improved, there has been only little dramatic change in overall treatment and results.1–3

It is estimated that more than 600,000 amputations are performed annually in patients with diabetes in the United States.3,4 It is further estimated that approximately half of these patients will develop ulceration and infection in the contralateral limb in the 18 months following amputation.3,4 Slightly more than half of these patients, in turn, have contralateral amputations in 3 to 5 years, and their mortality rate after the first amputation is 20–50%.3,4

Individuals with diabetes also have an increased risk of infection with subsequent complications secondary to impaired macrophage and cellular immune responses.4–7 Their nonhealing lower-extremity ulcers may lead to lower-extremity amputation, which is at least 14 times more likely to occur in persons with diabetes than those without diabetes.3,4 In 1997, inpatient, outpatient, and outpatient pharmaceutical medical expenditures incurred by the diabetic population totaled $77.7 billion.3,4 The total direct and indirect cost of care related to diabetes was estimated at $98 billion.3,5 Recent articles4,6 reported costs for nonoperable treatment of a single ulcer to be $7,000–$8,000. Treatment of infected ulcers cost more than $17,000, while amputations cost almost $45,000.

Lower-extremity wounds associated with arterial insufficiency have poor healing potential. For this reason, they are typically excluded from clinical trials for wound healing treatments. As a result, many wound healing products are contraindicated in ischemic wounds. However, arterial insufficiency is a frequent complicating factor in many lower-extremity wounds, including nonhealing leg and foot ulcers in patients with diabetes.1,3,7,8 In the United States, the incidence of amputations for ischemic disease was estimated to be 2.5 per 10,000 per year.5 Although revascularization is accepted as the primary means of reducing the risk of amputation in these patients,6,7 some patients are not able to receive revascularization due to medical comorbidity or the lack of a suitable outflow vessel in the limb. Nehler et al.8 suggested primary amputation for such patients.

In addition, some patients may receive revascularization and do not achieve results that completely alleviate ischemia due to diminished number of outflow vessels, focal ischemia due to smaller vessel blockage, or lack of collateral arterial flow.9,10

In the authors’ wound healing practice, a large number of patients with diabetes who are maximally treated for ischemia are seen with recalcitrant, nonhealing, lower-extremity wounds. Some degree of ischemia is apparent in the majority of these patients. The authors have developed a variety of techniques for dealing with these wounds, including medication and advanced wound healing techniques.10 These techniques are reported here.11–16

Materials and Methods

Thirty consecutive patients with diabetes, ischemia, and chronic wounds of the ankle and foot were treated over an 18-month period. Patients had appropriate moist wound care, and their wounds failed to heal for 5 weeks or more (average = 11 weeks, range 5–60 weeks). All patients were ambulatory and had a history of at least 1 severe infection of the wound area (average 1.5, range 1–3). Wounds were colonized with methicillin-resistant Staphylococcus aureus (MRSA) (12), vancomycin-resistant enterococcus (VRE) (5), or MRSA and another organism (13), usually pseudomonas or a streptococcus species. All cultures from the episodes of cellulitis were positive for VRE, MRSA, or both, and these were the suspected infecting organisms. All patients gave informed consent for their procedures. All cases were initially referred to and seen weekly by the same physician (SNC). The patients in this report received most of their wound care on an outpatient basis. Wound size varied from 2.0 cm x 3.2 cm x 0.3 cm to 8 cm x 5 cm x 1 cm (average = 22.5 cm3). All patients had modest-moderate neuropathy as determined by the physician on initial examination with use of a disposable Semmes-Weinstein monofilament.

Ages were 22–83 years (average 62 years). There were 14 men and 16 women. Five patients were in renal dialysis. Pain was assessed throughout the treatments using a 0–10 visual analog pain scale where 0 is no pain at all and 10 is the worst pain imaginable.17

All wounds were offloaded as needed prior to wound treatments. Diabetic and nutritional status was assessed and corrected when needed, but a strict control of diabetes was not achieved (average HbA1c was 7.5, plasma glucose 160–200 mg/dL).

All patients had some form of arterial ischemia as determined by arterial duplex Doppler scans, toe pressures of 35–50 mmHg, and ankle brachial indices. Ischemia was corrected as much as possible in all patients. Twenty patients received bypass or angioplasty for their lower-extremity ischemia. Ankle brachial index (ABI) was defined as the ratio of the systolic blood pressure in the ankle divided by the systolic blood pressure at the arm. The tools required to perform the ABI measurement included a hand-held 5–10 MHz Parks Model 811-B Doppler probe (Parks Medical Electronics, Inc., Aloha, Ore) and a blood pressure cuff. The ABI was measured by placing the patient in a supine position for 5 minutes. Systolic blood pressure was measured in both arms, and the higher value was used as the denominator of the ABI. Systolic blood pressure was then measured in the dorsalis pedis and posterior tibial arteries by placing the cuff just above the ankle. The higher value was the numerator of the ABI in each limb. The diagnostic criteria for peripheral arterial disease (PAD) were based on the ABI and interpreted as follows: normal 0.91–1.30; mild obstruction 0.70–0.90; moderate obstruction 0.40–0.69; severe obstruction < 0.40; and poorly compressible > 1.30. A modified Parks Model Pneumoplethysmograph was used to measure toe pressures.

After the patient was admitted to the wound care program and offloaded where needed, correction of nutrition and diabetes control was reasonably obtained. It is noteworthy that at least half of the patients seen still required offloading of the chronic wounds. Moist wound care dressings with hydrogel and maintenance sharp debridement were continued until successful offloading was achieved.

Since no progression of healing had been noted, patients were treated with human fibroblast-derived dermal substitute (Dermagraft™, Smith & Nephew Inc., Largo, Fla) and silver dressings (Silverlon™, Argentum Medical LLC, Willowbrook, Ill). Sharp debridement of the wounds was performed prior to application of the dermal substitute and silver dressing and was repeated as necessary throughout the course of therapy. The dermal substitute was thawed and applied to the wound area. The silver dressing was moistened with water and placed over the dermal substitute. The silver dressing was changed every 7 days. A dressing consisting of a hydrogel and semi-occlusive gauze was placed over the silver dressing to provide moisture as needed. The dermal substitute was not debrided, and a new dermal substitute was applied over the previous graft at 15-day intervals. Wounds were debrided at this dressing change if necrosis and excessive slough were present. Care was taken not to disturb the grafts, although most graft tissues were incorporated at this 15-day interval. The healing progression of the wounds was evaluated weekly. If no response to the dermal substitute was noted after 2 grafts, no additional dermal substitute would be offered; however, this did not occur.

When wounds were thoroughly granulated, and if no clinical infection was present as determined by clinical signs and symptoms (ie, erythema or excessive swelling in the wound area, significantly increased pain in the area, purulent discharge collected beneath the skin or draining from the wound, foul odor from the wound, systemic signs of infection), the patient would continue on moist wound care using silver dressings without a dermal substitute.18 If epithelization did not begin and progress over the next 2 weeks, a skin graft would be offered.

Results

Seventeen patients progressed to satisfactory healing and spontaneous closure by 84 days (average 46 days, range 32 to 94 days). Eight patients required skin grafts that healed. All patients had ABIs recorded, and none of the patients were categorized into the incompressible group.

Previous studies suggested that results of toe pressure measurement are predictive of wound healing.9 These studies reported that wounds with toe pressures < 30 mmHg are unlikely to heal, while those with pressures of 30–50 mmHg may have more potential for healing. Ankle brachial index is also reproducible and a reasonably accurate, noninvasive measurement for the detection of PAD and the determination of disease severity.10 Table 1 lists the patient population characteristics, including ABIs.

Five patients did not heal and required amputation. Two patients required single toe amputations and had toe pressures < 30 mmHg and ABIs < 0.50. Three patients required below-knee amputations and had ABIs < 0.40–0.35, 0.38, and 0.36, respectively. These patients’ wounds subsequently healed.

Healing was maintained on follow-up at 20 weeks in the 25 patients that healed or had skin grafts. There were no episodes of cellulitis or infection once silver dressings and the dermal substitute were instituted in any of the patients.

Initially, pain was relatively high (average 7/10, range 3 to 10/10) but averaged 3/10 after the third week of dermal substitute and silver dressing treatment.

Discussion

Thirty consecutive patients with diabetes and infected chronic wounds of the feet were treated with silver dressings and a human fibroblast-derived dermal substitute. Patients had appropriate moist wound care and failed to heal for 5 weeks or more before instituting this treatment (average = 11 weeks, range 5–60 weeks). All wounds were associated with at least a single episode of cellulitis and were cultured for methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococcus, or both. Clearly, not all wounds were infected at all times, but cultures were consistent throughout this report. Patients were regularly treated in the wound care program with maintenance sharp debridement and moist silver dressings. A dermal substitute was applied with silver dressings every 15 days until healing or skin graft application.

Seventeen patients progressed to satisfactory healing and spontaneous closure (Figure 1–3). Eight patients required skin grafts that subsequently healed. Healing was maintained on follow-up at 8 weeks in all patients. There were no episodes of cellulitis or infection once silver dressings were instituted. Five patients required amputation for their nonhealing wounds, and all of these wounds subsequently healed. The patients with nonhealing wounds who required amputation were those patients with greater ischemia as compared to the group as a whole, but other patients had similar ischemia and healed. In the amputation group, 3 patients were on dialysis, while only 2 patients who healed were on renal dialysis. Pain was markedly relieved once healing had begun with use of silver dressings and the dermal substitute but was also relieved in those patients that underwent amputation after institution of silver dressings and the dermal substitute.

Chronic foot and lower-extremity wounds of patients with diabetes generally occur as a result of unrecognized neuropathy and repetitive trauma that results in injury. Once established, these wounds in patients with diabetes may not heal and may lead to limb loss. Despite the progress that has been made in recent years to better understand and treat these complex chronic wounds, many wounds still do not respond well to existing treatments.19,20 These wounds frequently have other contributing factors including arterial ischemia and infection.21 All of these complicating factors were present in the wounds seen here, which required multimodal advanced wound care including dermal substitutes and silver dressings.

It is likely that multiple components of the dermal substitute (ie, growth factors, cytokines, matrix proteins, and glycosaminoglycans) that are not found in the other modalities assisted in this process of wound repair and provided a substrate that allowed fibroblast and epithelial cell migration that eventually achieved wound closure.22

Clinically, patients are developing more frequent infections and colonization with antibiotic-resistant bacteria.23,24 Concomitantly, new roles for broad-spectrum antimicrobial dressings are being continuously found.25 Silver dressings have no apparent sensitizing effect that frequently accompanies topical antibiotics and chemicals, and silver at concentrations readily found in the silver-plated cloth dressings do not appear to induce resistance.26 Additionally, use of silver dressings may have other effects potentiating healing, including epithelization.27 The antimicrobial effect as well as the increased healing potential and epithelization has prompted the authors to use these dressings to cover skin grafts placed over chronic wounds and as a primary dressing for chronic wounds. Reduction of pain and concomitant inflammation, slough, and odor has been reported with silver dressings as seen here.27 As noted, this is a highly desirable effect that is particularly useful in the trauma and wound patient who has chronic, severe pain.

Conclusion

Many treatments have been developed and are utilized to treat ischemic wounds. The authors’ approach to treatment, like many, is a combination of multiple advanced wound healing modalities and techniques. It is clear that any initial physical arterial obstruction should be corrected as best as possible before continuing treatment. In many instances, this will not result in total circulatory correction as reported here. The use of dermal grafts and silver dressings can be useful in obtaining full wound healing and assisting in wound closure.

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References

1. Laing P. The development and complications of diabetic foot ulcers. Am J Surg. 1998;176(2A Suppl):11S–19S.
2. Marston WA, Hanft J, Norwood P, Pollak R; Dermagraft Diabetic Foot Ulcer Study Group. The efficacy and safety of Dermagraft in improving the healing of chronic diabetic foot ulcers: results of a prospective randomized trial. Diabetes Care. 2003;26(6):1701–1705.
3. Reiber GE, Lipsky BA, Gibbons GW. The burden of diabetic foot ulcers. Am J Surg. 1998;176(2A Suppl):5S–10S.
4. Consensus Development Conference on Diabetic Foot Wound Care: 7–8 April 1999, Boston, Massachusetts. American Diabetes Association. Diabetes Care. 1999;22(8):1354–1360.
5. Rich J, Veves A. Forefoot and rearfoot plantar pressures in diabetic patients: correlation to foot ulceration. WOUNDS. 2000;12(4):82–87.
6. Wieman TJ, Smiell JM, Su Y. Efficacy and safety of a topical gel formulation of recombinant human platelet-derived growth factor-BB (becaplermin) in patients with chronic neuropathic diabetic ulcers: a phase III randomized placebo-controlled double-blind study. Diabetes Care. 1998;21(5):822–827.
7. McNeely MJ, Boyko EJ, Ahroni JH, et al. The independent contributions of diabetic neuropathy and vasculopathy in foot ulceration. How great are the risks? Diabetes Care. 1995;18(2):216–219.
8. Nehler MR, Hiatt WR, Taylor LM Jr. Is revascularization and limb salvage always the best treatment for critical limb ischemia? J Vasc Surg. 2003;37(3):704–707.
9. Kalani M, Brismar K, Fagrell B, Ostergren J, Jorneskog G. Transcutaneous oxygen tension and toe blood pressure as predictors for outcome of diabetic foot ulcers. Diabetes Care. 1999;22(1):147–151.
10. Carson SN, Overall K. Adjunctive therapy for ischemic wounds using cilostazol. WOUNDS. 2003;15(3):77–82.
11. Frykberg RG, Armstrong DG, Giurini J, et al. Diabetic Foot Disorders: A Clinical Practice Guideline. Brooklandville, Md: Data Trace Publishing Co, 2000.
12. Gentzkow GD, Jensen JL, Pollock RA, et al. Improved healing of diabetic foot ulcers after grafting with a living human dermal replacement. WOUNDS. 1999;11(3):77–84.
13. Robson MC, Steed DL, McPherson JM, Pratt BM. Use of transforming growth factor beta 2 (TGF-beta2) in the treatment of chronic foot ulcers in diabetic patients. Wound Repair Regen. 1999;7(4):A266.
14. Wu L, Xia YP, Roth SI, Gruskin E, Mustoe TA. Transforming growth factor-beta1 fails to stimulate wound healing and impairs its signal transduction in an aged ischemic ulcer model: importance of oxygen and age. Am J Pathol. 1999;154(1):301–309.
15. APhA drug treatment protocols: management of foot ulcers in patients with diabetes. J Am Pharm Assoc. 2000;40(4):467–474.
16. McGuckin M, Stineman MG, Goin JE, Williams SV. Venous Leg Ulcer Guideline. Wayne, Pa: Health Management Publications Inc.; 1997.
17. Bergstrom N, Allman RM, Alvarez OM, et al. Clinical Practice Guideline Number 15: Treatment of Pressure Ulcers. Rockville, Md: US Department of Health and Human Services. Agency for Health Care Policy and Research; 1994. AHCPR Publication No. 95-0652.
18. Littman GS, Walker BR, Schneider BE. Reassessment of verbal and visual analog ratings in analgesic studies. Clin Pharmacol Ther. 1985;38(1):16–23.
19. Stotts NA. Determination of bacterial burden in wounds. Adv Wound Care. 1995;8(4):46–52.
20. Eisenbud D, Huang NF, Luke S, Silberklang M. Skin substitutes and wound healing: current status and challenges. WOUNDS. 2004;16(1):2–17.
21. Mulder G, Armstrong D, Seaman S. Standard, appropriate, and advanced care and medical-legal considerations: part one—diabetic foot ulcerations. WOUNDS. 2003;15(4):92–106.
22. Volpato S, Blaum C, Resnick H, Ferrucci L, Fried LP, Guralnik JM; Women’s Health and Aging Study. Comorbidities and impairments explaining the association between diabetes and lower extremity disability: The Women’s Health and Aging Study. Diabetes Care. 2002;25(4):678–683.
23. Lodise TP, McKinnon PS, Tam VH, Rybak MJ. Clinical outcomes for patients with bacteremia caused by vancomycin-resistant enterococcus in a level 1 trauma center. Clin Infect Dis. 2002;34(7):922–929.
24. Velmahos GC, Toutouzas KG, Sarkisyan G, et al. Severe trauma is not an excuse for prolonged antibiotic prophylaxis. Arch Surg. 2002;137(5):537–541; discussion 541–542.
25. Thomas S, McCubbin P. A comparison of the antimicrobial effects of four silver-containing dressings on three organisms. J Wound Care. 2003;12(3):101–107.
26. Demling RH, DeSanti L. The rate of re-epithelialization across meshed skin grafts is increased with exposure to silver. Burns. 2002;28(3):264–266.
27. Wilson V. Assessment and management of fungating wounds: a review. Br J Community Nurs. 2005;10(3):S28–34.

Wounds - ISSN: 1044-7946 - Volume 17 - Issue 10 - October 2005 - Pages: 282 - 289

http://www.woundsresearch.com/article/4779

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Reducing Bacterial Bioburden in Infected Wounds with Vacuum Assisted Closure and a New Silver Dressing—A Pilot Study

- Allen Gabriel, MD;1 Cherrie Heinrich, MD;1 Jaimie T. Shores, MD;1 Waheed K. Baqai, MPH;2 Frank R. Rogers, MD;1 Subhas Gupta, MD, PhD1

Abstract: The use of silver is increasing rapidly in the management of infected wounds and wounds at risk for infection. This 5-patient case series reviews the results of a pilot study designed to determine efficacy and safety of negative pressure wound therapy (NPWT; V.A.C.® Therapy™, KCI, San Antonio, Tex) with the new silver foam dressing (V.A.C.® GranuFoam® Silver™ Dressing, KCI). Data on wound progression and the primary endpoints—time to clear infection, time to wound closure, and time to discharge from hospital—are detailed in this manuscript. For the 5 patients treated with NPWT and the silver foam dressing, the mean time for treatment was 13.00 ± 3.39 days and the mean time to patient discharge was 16.00 ± 6.63 days. Wounds were clear of clinical signs of infection in 7.00 ± 1.58 days and closed in 19.20 ± 8.76 days.

Infections complicate the treatment of wounds and impede the healing process by damaging tissue, reducing wound tensile strength, and inducing an undesirable inflammatory response.1,2 Increased bacterial burden in a wound increases the metabolic requirements of the tissues, stimulates a proinflammatory environment, and encourages the in-migration of monocytes, macrophages, and leukocytes—all of which can negatively impact wound healing.

Bacteria can also secrete harmful cytokines, which can lead to direct vasoconstriction and decreased blood flow to the wound.3 Thus, controlling or preventing infections is essential in order for the normal wound healing process to occur. In addition, reduction of infection can also yield significant overall cost savings in healthcare, as infections lead to thousands of dollars in excess medical charges and lengthened hospital stays every year.4

Negative pressure wound therapy (NPWT; V.A.C.® Therapy™, KCI, San Antonio, Tex) was introduced by Argenta and Morykwas in 1995 to aid in the healing process by removing interstitial fluid and infectious materials through the application of localized negative pressure to the wound.5,6 The negative pressure applied to the foam of the NPWT system induces undulations in the wound surface, thereby stretching cells and promoting cell division and the proliferation of reparative granulation tissue.7 Scientific studies have also demonstrated that the therapy promotes blood flow.6,8 In clinical practice, the authors have found that NPWT can enhance the reliability of surgical procedures and have incorporated its use in a wide variety of applications, such as acute traumatic wounds, chronic wounds, dehisced wounds, degloving injuries, burns, pre- and post-skin graft applications and flap procedures, and in conjunction with skin substitutes.9–17

Ionic silver has long been recognized as an effective antimicrobial agent used against a broad spectrum of pathogens and is considered to be biocompatible with mammalian tissue.18–23 The authors hypothesized that combining the antimicrobial activity of silver with the proven clinical benefits of NPWT would effectively reduce bacterial bioburden in wounds. For this pilot study, NPWT was applied with the new microbonded silver foam dressings (V.A.C.® GranuFoam® Silver™ Dressing, KCI) designed specifically to be used with this NPWT system.

Patients and Methods

A prospective case series of 5 consecutive patients with infected wounds treated with NPWT and the silver foam dressing was conducted. Each patient met the following inclusion criteria: at least age 18 with complex, open, infected wounds. Patient age ranged from 26 to 49 years. Three men and 2 women were treated. Four wounds resulted from open fractures sustained during motor vehicle accidents, and 1 wound resulted from a surgical abdominal wound dehiscence. The total area of the wounds ranged from 5 cm2 to 100 cm2, and the mean wound area was 43.00 cm2 ± 42.22 cm2 (Tables 1 and 2).Table 2

All wounds were sharply debrided of nonviable tissue before NPWT was applied. For all patients, a swab of soft tissue was taken and submitted on Day 1 of hospital admission for qualitative culture analysis. For Patient 1, the silver foam dressing was applied on hospital Day 30 following 30 days of NPWT with the standard foam dressing. For the remaining 4 patients, NPWT with the silver foam dressing was initiated as a first line therapy upon admission, following initial surgical debridement.

The US Food and Drug Administration-approved silver foam dressing used in this case series is an open-celled, reticulated polyurethane foam that is microbonded with metallic silver via a proprietary metalization process (Figure 1).Figure 1

The silver foam dressing was placed in the entire wound cavity and covered with an adhesive drape to create an airtight seal. A 1–2 cm round hole was cut into the drape. A T.R.A.C.® pad with tubing was applied directly over the hole and connected to a fluid collection canister, which is contained within the computer-controlled NPWT device.

No interface or adjunctive antimicrobial dressings were used with the silver foam dressing. This allowed for direct and complete contact of the dressing with the wound bed. For each wound, the NPWT device was programmed to deliver –125 mmHg continuous pressure, with dressing changes every other day. When the wounds were granulated to the surface and could be closed primarily or via secondary intention NPWT with the silver foam dressing was discontinued. Time to wound closure was defined by complete closure of the wound either by primary or secondary intention. Wound progression data and the primary endpoints—time to clear infection, time to wound closure, and time to discharge from hospital—were documented and recorded for all 5 patients (Table 1). Age, wound area, history of diabetes, and albumin levels were also recorded (Table 2).

Descriptive statistics and statistical analyses were calculated using SPSS 12.0 (SPSS Inc, Chicago, Ill) to determine demographic and result endpoints for the silver foam dressing-treated patients. All categorical variables are expressed as frequency and percentages, while continuous variables are expressed as the mean ± standard deviation, unless otherwise stated.

Results

No complications were experienced during the application of the silver foam dressings for any of the 5 patients. All wounds progressed to the point of primary or secondary closure. The times to infection clearance and wound closure were 7.00 ± 1.58 and 19.20 ± 8.76 days, respectively. The mean number of days required for treatment was 13.00 ± 3.39 days, and healthy granulation tissue was present in 5.50 ± 2.08 days. Mean time to patient discharge was 16.00 ± 6.63 days (Tables 1 and 3).Table 3

Case Reports

Case 1. A 49-year-old man was admitted with an infected, open, left ankle wound. Six months prior to this admission, the patient sustained a distal tibial fracture, which was plated during surgery immediately following the incident. Upon this admission, the wound cultured positive for Staphylococcus and vancomycin-resistant Enterococci (VRE). Antibiotic therapy was initiated immediately for a total of 1 week. The infected plate was removed, and the wound was surgically debrided. The resulting wound area was 100 cm2 with exposed bone and tendon.

On Day 3 post surgical debridement and removal of the plate (Figure 2A), NPWT was initiated with the traditional foam dressing at –125 mmHg continuous pressure. Screw holes in exposed bone are visible in Figure 2A. On NPWT Day 22, the wound was 90% granulated (Figure 2B). However, on Day 30, the wound still cultured positive for VRE, which prompted a switch to treatment with the silver foam dressing (Figure 2C).Figure 2

On Day 35 of NPWT including 5 days with the silver foam dressing, the wound cultured negative for all clinical infection, including VRE (Figure 2D). Two days later, the wound was grafted with a bilayer matrix dermal regeneration template (Integra™, Integra LifeSciences Corporation, Plainsboro, NJ) on Day 37. The patient then underwent a split-thickness skin graft (STSG) on Day 39 and was discharged home (Figure 2E). The silver foam dressing was used on top of both the bilayer matrix template and the STSG.14,16 A nonadherent dressing was placed between the silver foam and the skin grafts per recommended protocol.24,25 On Day 42, NPWT was discontinued, and the STSG had 100% take without any sloughing or signs of infection. The wound remained closed at the 3-month follow-up visit (Figure 2F).

Case 2. A 47-year-old man sustained an ankle fracture 2 years prior to admission and presented with a necrotic wound over the prior surgical site. The wound culture returned positive for Staphylococcus, Enterococcus, Pseudomonas, Enterobacter, and Klebsiella. Further assessment revealed chronic osteomyelitis, which had been present and treated for 2 years. Upon admission, 6 weeks of antibiotic therapy were prescribed to treat the chronic osteomyelitis. The wound was surgically debrided, and the resulting wound measured 75 cm2 (Figure 3A). Immediately following surgical debridement, NPWT was initiated with the silver foam dressing at –125 mmHg continuous pressure.Figure 3

On Day 6 of using the silver foam dressing, healthy granulation tissue was observed, and the wound cultured negative for all bacterial organisms. On Day 12, the wound was considerably smaller and covered with granulation buds (Figure 3B). On Day 15, the dressing was switched to traditional foam dressing (Figure 3C). The wound was further contracted on Day 22 (Figure 3D). Negative pressure wound therapy with the standard foam dressing was applied until Day 27 (Figure 3E), at which time the wound was fully granulated to the surface, and the therapy was discontinued. The patient was discharged home with a nonadherent dressing over the wound to optimize re-epithelization. The closed wound at 2-month follow-up post discontinuation of NPWT with the silver foam dressing is shown in Figure 3F.

Case 3. A 42-year-old man sustained a pilon fracture 2 years prior to admission and presented with a chronic open ankle wound. Due to infection, hardware had been removed 3 months prior to presentation. A culture returned positive for VRE. The total area of the wound after debridement was 10 cm2 (Figure 4A). Immediately following debridement, NPWT was initiated with the silver foam dressing at –125 mmHg continuous pressure (Figure 4B). Healthy granulation tissue was observed on Day 3 (Figure 4C), and the wound was further contracted on Day 5 (Figure 4D). On Day 9, the wound culture returned negative for VRE infection (Figure 4E). No systemic antibiotics were used during the length of therapy for this patient. Negative pressure wound therapy was applied for 15 days with the silver foam dressing at which point the wound was closed and the patient was discharged home (Figure 4F).Figure 4

Case 4. A 26-year-old woman sustained a proximal ulnar fracture from a motor vehicle accident. The patient was admitted with an infected, open ulnar fracture with exposed bone 5 days following the accident. The total area of the wound after debridement was 25 cm2 (Figure 5A). A wound culture returned positive for Staphylococcus aureus and Enterococcus. Negative pressure wound therapy was initiated with the silver foam dressing at –125 mmHg continuous pressure (Figure 5B). The silver foam dressing was applied for 14 days. No systemic antibiotics were used during the length of NPWT for this patient. The wound cultured negative for infection on Day 8. On Day 14, the wound was fully granulated and the patient was discharged for a STSG at another facility (Figure 5C).Figure 5

Case 5. A 45-year-old woman with a history of type II diabetes mellitus, coronary artery disease, and obesity (body mass index of 56) was taken to the operating room for an open appendectomy and discharged home on postoperative Day 2. The patient subsequently presented to the emergency room on postoperative Day 5 with purulent drainage from the wound. She was admitted, and the wound was debrided. The total area of the wound after debridement was 5 cm2. A wound culture returned positive for Staphylococcus aureus and Enterococcus, at which time NPWT was initiated with the silver foam dressing at –125 mmHg continuous pressure. Negative pressure wound therapy was applied for 14 days with the silver foam dressing. No systemic antibiotics were used during the length of therapy for this patient. The wound cultured negative for infection on Day 7. On Day 14, the wound was fully granulated to the surface and contracted. Negative pressure wound therapy was discontinued and the patient was discharged home with antibiotic ointment and gauze. Complete re-epithelized closure was achieved on Day 20.

Discussion

From the present experience, the authors found the NPWT with the silver foam dressing to be a safe and efficacious adjunct in reducing bacterial bioburden in these wounds. The initial treatment results were noteworthy and showed a marked reduction in infection, wound closure time, and hospital stay over the institution’s historically employed use of moist wound therapy for the management of infected wounds. The sample size of this prospective case series of 5 consecutive patients treated with the silver foam dressing is relatively small and was meant to minimize patient risk.

The authors have found the new silver foam dressing to be most useful in cases of complex, colonized, or infected wounds post debridement, as well as for acute traumatic wounds for reduction of bacterial bioburden. It is a preferred dressing to help reduce the risk of recurrent infection in patients who have severe comorbidities and a history of chronic wound colonization. The authors have also observed good results when the silver foam dressing is placed over a STSG, as the dressing has the necessary antimicrobial coverage in addition to the bolstering effect of NPWT. Conversely, the authors would indicate the traditional foam dressing instead of the silver foam dressing for wounds that are clear of infection or have low risk of recurrent infection.

In the past, the authors have used other silver antimicrobial dressings in combination with the traditional foam dressing with mixed results. Some silver dressings led to adverse reactions in wound healing, and other dressings have not provided the antimicrobial coverage needed to decrease the bacterial bioburden. In addition, some of the silver dressings do not have the wound conformability needed to eliminate areas of noncontact, which may allow bacteria to proliferate in those areas.26 It has also been shown that negative pressure can be affected when an interface layer is used between the foam dressing and the wound.27

Use of the silver foam dressing in conjunction with NPWT offers a sufficient antimicrobial effect and a good bridge to wound healing. This may be due to a combination of factors including nontoxic levels of silver release (2–3 parts per million [ppm]), optimal wound conformability, nontraumatic exudate removal, and the proven clinical benefits of NPWT. In addition, the silver foam dressing is “user-friendly,” as it does not require adjunctive antimicrobial dressings beneath the foam.

In each of the 5 cases, use of the silver dressing was continued past the point of infection clearance to act as a barrier to further bacterial penetration.2 There were no incidences of recurrent infection. In 2 of the 5 cases, systemic infection was present, and intravenous antibiotics were administered to treat the invasive infection. In these situations, literature supports that topical antibiotic agents alone are not sufficient to reduce infection, and culture-specific systemic antibiotics should be prescribed.3 An additional risk for these 2 cases was insufficient systemic antibiotic delivery due to an ischemic lower extremity. In these instances, the silver foam dressing provided effective topical antimicrobial action in addition to the systemic antibiotics. Systemic antibiotics were not prescribed in the remaining 3 cases, as the presence of topical infection only was suspected. Bacterial bioburden was reduced and wound closure was achieved without the need for systemic antibiotics.

The resurgence of interest in silver products for wound care stems from the increase in the level of bacterial resistance to traditional antibiotics. For example, rates of methicillin-resistant Staphylococcus aureus (MRSA) increased steadily over the past decade from approximately 30% in 1989 to approximately 40% in 1997 among intensive care unit patients.28 Unlike traditional antibiotics, ionic silver has multiple mechanisms of action, such as inhibiting cellular respiration, denaturing nucleic acids, and altering cellular membrane permeability.29,30 An adequate concentration of silver coupled with its various mechanisms of action make it difficult for microorganisms to develop resistance to silver because they would have to undergo several mutations in order to develop defense mechanisms against silver’s multi-pronged attack.3

However, potential resistance to silver should be a consideration, and the adequate level of silver required for bioburden efficacy remains a controversial and complex issue. Some investigators believe low levels are enough, and others support the view that a higher level of silver is necessary for sufficient bacterial kill.29–31 There is no global standard for elution studies, and the literature varies drastically, from 1.0 ppm to more than 36 ppm, in the suggested requirements for the proper kill levels.31 A key confounding factor is that all pathogens have multiple strains, and different strains require different levels of silver for kill. There are also significant differences in methodology of measure, which complicate data interpretation of silver levels between various silver dressings.

Another important factor in measuring silver delivery is the ability of the dressing to conform to the wound site. Recent research indicates that the ability of a silver-containing dressing to conform to the contours of a wound is important to reduce areas of noncontact where bacteria may proliferate.26 The silver effect was evenly distributed to the entire wound surface with the silver foam dressing.

Scientific research has determined that the application of NPWT with a traditional foam dressing induces micromechanical effects at the dressing-to-tissue interface, resulting in tissue undulations and cellular microdeformation.32 The silver is microbonded to the silver foam dressing in such a way that the foam retains the same porosity and structure of the traditional foam dressing to simulate the same micromechanical effects (Figure 1). These localized micromechanical forces are thought to be a primary driver in cellular proliferation, angiogenesis, and stimulation of growth factors.7,32 Therefore, interface layers were not used between the wound and the silver foam dressing, except in cases of protecting exposed tendon or a split-thickness skin graft, in order to maximize the effectiveness of the NPWT.

Some authors have suggested that higher levels of silver delivered by agents, such as nanocrystalline silver, can be harmful to viable cells. This toxicity of silver is supported in several in-vitro studies.33,34 However, this is contrary to what the authors experienced in the clinic with this dressing. In each of the 5 cases in this series, use of the silver foam dressing was continued beyond the point of infection clearance because of consistently observed progression toward closure with the silver dressing. In 1 case, the silver foam dressing was applied over a split-thickness skin graft with the goal of bioburden reduction and enhanced graft take. The result was 100% graft take without sloughing or signs of infection. Demling and DeSanti35 published similar findings in a controlled study that showed a moistened silver delivery system placed over a meshed skin graft on an excised burn wound that significantly increased the rate of re-epithelization compared to a standard antibiotic bolster dressing.

A recent study sheds an interesting light on silver-containing dressings and their variable effects on cells. Cochrane et al36 used a fibroblast-seeded collagen gel model to evaluate the effect of 7 different silver-containing antimicrobial dressings on fibroblast contraction and viability. Of 7 dressings, 3 demonstrated less than 20% cell viability after 96 hours, compared to approximately 70% viability for the remaining 4 dressings. The authors concluded that silver dressing selection should be based on the overall characteristics of a dressing, including its antimicrobial, fluid-handling, physical, and chemical properties.

Numerous peer-reviewed publications support positive wound management aspects of nanocrystalline silver.35–38 Wright et al38 noted reduced levels of matrix metalloproteinases and a higher frequency of apoptosis in a porcine model of contaminated wounds treated with silver. The results suggest that nanocrystalline silver may play a role in altering or compressing the inflammatory events in wounds and facilitating the early phases of wound healing.

Conclusion

In this small, pilot study, NPWT with the new silver foam dressing demonstrated a reduction in the mean time to infection clearance, wound closure, and hospital discharge compared to the authors’ previous moist wound care therapy. By incorporating the new silver foam dressing into practice, the authors have been able to reduce bacterial bioburden in chronic and acute wounds, while allowing the wounds to progress to healing with a healthy granulating wound bed. This improved rate of wound healing has allowed the use of simpler procedures for closure and aversion of more complex procedures, such as free flaps, and their related expenses.39 Anecdotally, the authors have also noted a reduction in hospital length of stay for the patients treated with this combination therapy, which has yielded hospital savings in addition to the overall enhancement of patient quality of life. Further studies with larger patient samples hold promise for comparable results of this novel combination wound therapy.

References

1. Wright JB, Hansen DL, Burrell RE. The comparative efficacy of two antimicrobial barrier dressings: in vitro examination of two controlled release silver dressings. WOUNDS. 1998;10(6):179–188.
2. Yin HQ, Langford R, Burrell RE. Comparative evaluation of the antimicrobial activity of Acticoat antimicrobial barrier dressing. J Burn Care Rehabil. 1999;20(3):195–200.
3. Warriner R, Burrell R. Infection and the chronic wound: a focus on silver. Adv Skin Wound Care. 2005;18(Suppl 1):2–12.
4. Zhan C, Miller MR. Excess length of stay, charges, and mortality attributable to medical injuries during hospitalization. JAMA. 2003;290(14):1868–1873.
5. Argenta LC, Morykwas MJ. Vacuum-assisted closure: a new method for wound control and treatment: clinical experience. Ann Plast Surg. 1997;38(6):563–577.
6. Morykwas MJ, Argenta LC, Shelton-Brown EI, McGuirt W. Vacuum-assisted closure: a new method for wound control and treatment: animal studies and basic foundation. Ann Plast Surg. 1997;38(6):553–562.
7. Orgill DP, Bayer LR, Neuwalder J, Felter RC. Microdeformational wound therapy—a new era in wound healing. Global Surgery—Future Directions in Surgery 2005. 2005;22–25.
8. Wackenfors A, Sjogren J, Gustafsson R, et al. Effects of vacuum-assisted closure therapy on inguinal wound edge microvascular blood flow. Wound Repair Regen. 2004;12(6):600–606.
9. Gupta S, Baharestani M, Baranoski S, et al. Guidelines for managing pressure ulcers with negative pressure wound therapy. Adv Skin Wound Care. 2004;17(Suppl 2):1–16.
10. Joseph E, Hamori CA, Bergman S, et al. Prospective randomized trial of vacuum-assisted closure versus standard therapy of chronic non-healing wounds. WOUNDS. 2000;12(3):60–67.
11. DeFranzo AJ, Argenta LC, Marks MW, et al. The use of vacuum-assisted closure therapy for the treatment of lower-extremity wounds with exposed bone. Plast Reconstr Surg. 2001;108(5):1184–1191.
12. Meara JG, Guo L, Smith JD, et al. Vacuum-assisted closure in the treatment of degloving injuries. Ann Plast Surg. 1999;42(6):589–594.
13. Armstrong DG, Lavery LA, Abu-Rumman P, et al. Outcomes of subatmospheric pressure dressing therapy on wounds of the diabetic foot. Ostomy Wound Manage. 2002;48(4):64–68.
14. Gupta S, Gabriel A, Shores JT. The perioperative use of negative pressure closure in skin grafting. Ostomy Wound Manage. 2004;50(Suppl 4A):32–34.
15. Fife CE, Otto G, Walker D, Turner T, Smith L. Healing dehisced surgical wounds with negative pressure wound therapy. Ostomy Wound Manage. 2004;50(Suppl 4A):28–31.
16. Molnar JA, DeFranzo AJ, Hadaegh A, et al. Acceleration of Integra incorporation in complex tissue defects with subatmospheric pressure. Plast Reconstr Surg. 2004;113(5):1339–1346.
17. Morykwas MJ, David LR, Schneider AM, et al. Use of subatmospheric pressure to prevent progression of partial-thickness burns in a swine model. J Burn Care Rehabil. 1999;20(1 Pt 1):15–21.
18. Vanscheidt W, Lazareth I, Routkovsky-Norval C. Safety evaluation of a new ionic silver dressing in the management of chronic ulcers. WOUNDS. 2003;15(11):371–378.
19. O’Meara SM, Cullum NA, Majid M, Sheldon TA. Systematic review of antimicrobial agents used for chronic wounds. Br J Surg. 2001;88(1):4–21.
20. White RJ. An historical overview of the use of silver in wound management. Br J Nurs. 2001;10(15 Suppl 2):S3–S8.
21. Demling RH, DeSanti L. The role of silver technology in wound healing: effects of silver on wound management. WOUNDS. 2001;13(5):15–21.
22. Burrell RE, Heggers JP, Davis GJ, Wright JB. Efficacy of silver-coated dressings as bacterial barriers in rodent burn sepsis model. WOUNDS. 1999;11(4):64–71.
23. Tredget EE, Shankowsky HA, Groeneveld A, Burrell R. A matched-pair, randomized study evaluating the efficacy and safety of Acticoat silver-coated dressing for the treatment of burn wounds. J Burn Care Rehabil. 1998;19(6):531–537.
24. Weinfeld AB, Kelley P, Yuksel E, et al. Circumferential negative-pressure dressing (VAC) to bolster skin grafts in the reconstruction of the penile shaft and scrotum. Ann Plast Surg. 2005;54(2):178–183.
25. 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.
26. Jones SA, Bowler PG, Walker M. Antimicrobial activity of silver-containing dressings is influenced by dressing conformability with a wound surface. WOUNDS. 2005;17(9):263–270.
27. Jones SM, Banwell PE, Shakespeare PG. Interface dressings influence the delivery of topical negative-pressure therapy. Plast Reconstr Surg. 2005;116(4):1023–1028.
28. Fridkin SK, Gaynes RP. Antimicrobial resistance in intensive care units. Clin Chest Med. 1999;20(2):303–316.
29. Ovington LG. The truth about silver. Ostomy Wound Manage. 2004;50(9A Suppl):1S–10S.
30. Driver VR. Silver dressings in clinical practice. Ostomy Wound Manage. 2004;50(9A Suppl):11S–15S.
31. Brett DW. A discussion of silver as an antimicrobial agent: alleviating the confusion. Ostomy Wound Manage. 2006;52(1):34–41.
32. Saxena V, Hwang C, Huang S, Eichbaum Q, Ingber D, Orgill DP. Vacuum-assisted closure: microdeformations of wounds and cell proliferation. Plast Reconstr Surg. 2004;114:1086–1096.
33. Drosou A, Falabella A, Kirsner R. Antiseptics on wounds: an area of controversy. WOUNDS. 2003;15(5):149–166.
34. Poon VK, Burd A. In vitro cytotoxicity of silver: implication for clinical wound care. Burns. 2004;30(2):140–147.
35. Demling RH, DeSanti L. The rate of re-epithelialization across meshed skin grafts is increased with exposure to silver. Burns. 2002;28(3):264–266.
36. Cochrane C, Walker M, Bowler P, Parsons D, Knottenbelt D. The effect of several silver-containing wound dressings on fibroblast function in vitro using the collagen lattice contraction model. WOUNDS. 2006;18(2):29–34.
37. Kirsner RS, Orsted H, Wright JB. Matrix metalloproteinases in normal and impaired wound healing: a potential role for nanocrystalline silver. WOUNDS. 2001;13(3 Suppl):4C–12C.
38. Wright JB, Lam K, Buret A, Olson ME, Burrell RE. Early healing events in a porcine model of contaminated wounds: effects of nanocrystalline silver on matrix metalloproteinases, cell apoptosis, and healing. Wound Repair Regen. 2002;10(3):141–151.
39. Greer S, Kasabian A, Thorne C, Borud L, Sims CD, Hsu M. The use of a subatmospheric pressure dressing to salvage a Gustilo grade IIIB open tibial fracture with concomitant osteomyelitis to avert a free flap. Ann Plast Surg. 1998;41(6):687.

Wounds - ISSN: 1044-7946 - Volume 18 - Issue 9 - September 2006 - Pages: 245 - 255

http://www.woundsresearch.com/article/6162

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Lymphedema People

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patoco
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Re: Silver Dressings and Wound Healing

Postby Carol Butler » Mon Sep 14, 2009 11:24 pm

Thanks Pat for answering my concerns. I have a doctor's appt. tomorrow and will let you know how it goes.

Now I understand more about the dermal graft. I had one called Applegraf. Even with all my problems, it seems as though it has taken. It looks pretty nasty around it though. They have been using the silver dressings on it. Golly, are they expensive!~! -not covered by insurance either~!

The doctor mentioned that I might like to think about removing my limb. I don't think so! Just because they
can't figure out what is wrong does not mean I am willing to just cut it off!
I'll let you know how it goes, but at least its nice to know someone feels my pain!
Thanks, Carol
Carol Butler
 
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Re: Silver Dressings and Wound Healing

Postby patoco » Tue Sep 15, 2009 8:00 am

Hi Carol

So good to hear from you, but OMG....glad you jus said NO to the leg removal idea.

Geezz....they suggested that me as well a few years back and I said the same thing - "thanks but no thanks"

That was actually 8 years ago, so for all their talk, it just wasn't necessary or even a smart idea.

A couple years ago I had a very long talk with a lmph doctor I know and was horrified to actually hear about what lymphers go through when a limb is amputated. It's really a worse nightmare then LE itself.

I was going to say too, that another member has been using honey for her wounds and has achieved quite a success from it.

There are some good studies out too that support honey's effectiveness.

I'll be looking forward to hearing how i goes for you!

All the best to you!

Pat
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