- Email: [email protected]
Impact of an Absorbent Silver-Eluting Dressing System on Lower Extremity Revascularization Wound Complications
Impact of an Absorbent Silver-Eluting Dressing System on Lower Extremity Revascularization Wound Complications Beverly B. Childress,1 Scott A. Berceli,2,3 Peter R. Nelson,2,3 W. Anthony Lee,2,3 and C. Keith Ozaki,2,3 Gainesville, Florida
Surgical wounds for lower extremity revascularization are prone to infection and dehiscence. Acticoat AbsorbentÒ, an antimicrobial dressing, offers sustained release of ionic silver. We hypothesized that immediate application of Acticoat as a postoperative dressing would reduce wound complications in patients undergoing leg revascularization. All infrainguinal revascularization cases involving leg incisions at a single Veterans Administration Medical Center were identified from July 1, 2002, to September 30, 2005. The control group received conventional dressings, while the treatment group received an Acticoat dressing. Wound complication rates were captured via National Surgical Quality Improvement Program data. Patient characteristics and procedure distributions were similar between groups. The wound complication rate fell 64% with utilization of the Acticoat-based dressing (control 14% [17/118], treatment 5% [7/130]; P ¼ 0.016). An Acticoat-based dressing system offers a potentially useful, cost-effective adjunct to reduce open surgical leg revascularization wound complications.
INTRODUCTION Approximately 27 million surgical procedures are performed annually in the United States.1 One of the most common postoperative complications is surgical site infection, which causes significant morbidity and health-care costs (estimated at $1.5 billion per year)2 among hospitalized patients.1 Surgical wounds for lower extremity revascularization are particularly prone to infection and dehiscence, with rates in some series as high as 44%.3 Currently, the Guideline for Prevention of Surgical Site Infection recommends the use of sterile dressing to 1 Veterans Affairs Office of Academic Affiliation, North Florida/ South Georgia Veterans Health System, Gainesville, FL. 2 Division of Vascular Surgery and Endovascular Therapy, University of Florida College of Medicine, Gainesville, FL. 3 Malcom Randall Veterans Administration Medical Center, Gainesville, FL.
Correspondence to: C. Keith Ozaki, M.D., Chief, Surgical Service (112), 1601 SW Archer Road, Gainesville, FL 32608, USA, E-mail: [email protected] Ann Vasc Surg 2007; 21: 598-602 DOI: 10.1016/j.avsg.2007.03.024 Ó Annals of Vascular Surgery Inc. Published online: May 23, 2007
598
protect closed incisions for 24-48 hr postoperatively.1 However, no evidence-based recommendations are made with regard to dressing types for use in postoperative incision care. A plethora of wound dressings are available on the market, with silver-based dressing among recent innovations. Topical silver is an effective bactericidal agent that does not induce bacterial resistance when used at therapeutic levels.4 Acticoat AbsorbentÒ (Smith and Nephew, London, UK), an antimicrobial barrier dressing, is coated with nanocrystalline silver that delivers a controlled, sustained (up to 3 days) dose of silver ions. Additionally, this dressing absorbs moisture (minimizing wound maceration) and is safe and effective against a broad range of microorganisms. Acticoat is indicated for chronic wounds and burn wounds;5,6 however, data are lacking regarding its potential role in postoperative surgical incision wound infection prophylaxis. Therefore, we hypothesized that immediate application of Acticoat in conjunction with an overlying occlusive dressing as a postoperative dressing would reduce closed incisional wound complications in patients undergoing lower extremity revascularization involving infrainguinal skin incisions.
Vol. 21, No. 5, 2007
Acticoat dressing for lower extremity revascularization
599
Using a nonconcurrent cohort study design and real-time clinical data collection, we compared patients who received conventional non-silvercontaining dressing with Acticoat as a postoperative dressing following defined lower extremity revascularization.
MATERIALS AND METHODS Sample Selection Appropriate institutional approval was secured for this study, which includes all open lower extremity revascularization patients from over a 39-month study period at a single Veterans Administration Medical Center. Conventional non-silvercontaining dressings (typically sterile cotton gauze, often in combination with an overlying occlusive plastic dressing) were utilized over the first 15 months of the study. Beginning with the sixteenth month, all closed incisions were dressed with Acticoat and an occlusive plastic dressing (Fig. 1). Adherence of the occlusive plastic was facilitated by use of an alcohol-based prep solution immediately before final bandage application. The clinical practice of the group was to leave the immediate postoperative dressing in place until it was grossly contaminated with fluid or remove it electively between postoperative days 2 and 4. All open lower extremity revascularization cases from July 1, 2002, to September 30, 2005, were identified by Current Procedural Terminology (CPT) codes from a prospectively collected relational database. No cases were excluded. Cases involving more than one of these procedures were listed once based on the quantity of surgical wound at risk for complication. For instance, a case involving a concurrent ileofemoral and femoral-to-anterior tibial bypass would be listed as an infrainguinal bypass.
Fig. 1. Acticoat postsurgery.
dressing
applied
immediately
Data Collection Clinical data (age at the time of procedure, gender, race [white versus nonwhite], history of diabetes, diagnosis of hypertension, current smoking practice, and procedural indications) were abstracted from patient medical records. Wound complications (failure to heal [wound dehiscence], superficial and deep soft tissue infections) were defined using the National Surgical Quality Improvement Program (NSQIP) criteria7 and captured via the NSQIP. Locally, the study center’s NSQIP data entry is facilitated by first-pass contribution of information entered in real time into a vascular surgery-specific
database by the attending surgeons. The clinical practice of the group was to manage the large majority of infections with empiric antibiotic coverage including drainage and debridement as needed; thus, microbiological profiles of the wounds are not available. Statistical Analysis Chi-squared analysis was performed to compare patient characteristics for categorical data, and independent samples t-tests were used for continuous variables using SPSS 14.0 for Windows software
600 Childress et al.
Annals of Vascular Surgery
(SPSS, Chicago, IL). Level of statistical significance was evaluated at P < 0.05.
Table I. Patient characteristics
RESULTS
Age (mean years ± SD) Male gender Race (white) Diabetes Hypertension Current smoking Creatinine >1.5 mg/L
The study population comprised 216 patients who underwent 248 cases that met inclusion criteria (Table I). Both groups were similar with regard to age at the time of first procedure, gender, race, diabetes, hypertension, current smoking, and renal insufficiency (creatinine >1.5 mg/L). Both groups had tissue loss as the most common indication for the lower extremity revascularization procedure, with 47% (55/118) for the control group and 38% (49/130) for the treatment group (Table II). Moreover, autogenous vein bypass graft was the most common procedure performed for the control (65/118, 55% of procedures) and treatment (54/130, 42% of procedures) groups (Table III). The surgeons and other providers found the dressing regimen easy to apply and care for postoperatively. Revascularization pulses could be palpated through the dressing, and the low profile permitted identification of postoperative soft tissue changes such as hematomas. Compressive Ace bandages could be applied without disturbing the original dressing. No substantial dressing material-specific complications were noted, including any apparent allergic reactions. The wound complication rate for the control group was 14% (17/118), and that for the treatment group was 5% (7/130) (Table III). Over the intervention phase, the wound overall complication rate fell by 64% (c2 ¼ 5.76, degrees of freedom ¼ 1, P ¼ 0.016).
DISCUSSION This single-institution, nonconcurrent cohort study suggests that an antimicrobial silver-eluting absorbent dressing held in place with an occlusive plastic bandage reduces lower extremity revascularization wound complications when applied immediately postsurgery. This is consistent with previous efficacy studies of silver-coated dressings in burn wounds and chronic wounds.5,6 The manufacturer claims immediate and sustained silver release from this material for up to 3 days. Consequently, this dressing kills a broad spectrum of bacteria within 30 min of application, including antibiotic-resistant strains of Pseudomonas, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant Enterococcus.8-12 The alginate component of this dressing material appeared to assist with early postoperative
Control group (n ¼ 99)
Treatment group (n ¼ 117)
65.8 ± 10 99 (100%) 80 (81%) 48 (49%) 77 (78%) 58 (59%) 13 (11%)
65.7 ± 10.8 115 (98%) 99 (85%) 55 (47%) 101 (86%) 59 (50%) 15 (12%)
No statistical difference between groups for all characteristics.
Table II. Operative indications
Indication Claudication Rest pain Tissue loss Failing bypass graft Acute leg ischemia Other
Control group (n ¼ 118)
Treatment group (n ¼ 130)
9 18 55 26 6 4
21 18 49 17 16 9
(8%) (15%) (47%) (22%) (5%) (3%)
(16%) (14%) (38%) (13%) (12%) (7%)
wound hygiene, absorbing fluid that wept from the incision, thus avoiding the skin maceration occasionally seen with other less absorbent materials. The patient demographics, clinical characteristics, and open revascularization approaches appear representative of a typical Veterans Administration vascular surgical patient population, though the male dominance of the group distinguishes it from a civilian practice. The infrainguinal open procedures for arterial revascularization were selected a priori based on the literature and the authors’ direct observation of higher wound complications in this patient subset. These broader inclusion criteria also avoided the potential Type II error that might have been associated with a more select study population from a single institution. The low rate of surgical interventions for claudication and the rare use of prosthetic conduits may not mirror all contemporary surgical practices. The observed wound complication rates compare favorably with the published benchmark.3 In an economic costs study among 255 patients with surgical site infection who were matched to noninfected patients, the total extra costs attributable to surgical site infection were almost $2 million.13 For vascular surgery alone, the median total direct cost for 11 infected patients was $12,261 and that for uninfected patients was $6,666 in 1999 ($5,595 direct cost differential).
Vol. 21, No. 5, 2007
Acticoat dressing for lower extremity revascularization
601
Table III. Procedure distribution and wound complication rates Wound complication
Procedure Vein bypass graft Revision vein graft Aortobifemoral bypass Femoral reconstruction Axillary-bifemoral/femoral-femoral bypass Ileofemoral bypass Thromboembolectomy Prosthetic bypass graft Other Overall wound complication
Control group (n ¼ 118)
Treatment group (n ¼ 130)
13/65 0/12 1/13 1/6 0/5 1/6 0/4 0/5 1/2 17/118
4/54 0/11 2/21 0/10 1/13 0/5 0/5 0/7 0/4 7/130
(20%) (0%) (8%) (17%) (0%) (17%) (0%) (0%) (50%) (14%)
(7%) (0%) (10%) (0%) (8%) (0%) (0%) (0%) (0%) (5%)*
*P ¼ 0.016 vs. control group.
Furthermore, the median total length of hospital stay for infected vascular surgical patients was 24, while that for the uninfected was 8, days. The current cost to our hospital for a single 4 x 5 inch piece of the Acticoat material and the overlying occlusive plastic is approximately $10. Based on the results of this small study, the number of patients needed to treat with this silver-based dressing system to prevent one wound complication is approximately 11. Put simply, a $110 investment not only saves the individual morbidity of a wound complication but offers a substantial overall direct health-care system cost benefit based on an estimated cost of $5,595 per wound infection. With the alarming increase in antimicrobial resistance and the growing number of surgical patients who are elderly with comorbid diseases, the total expenditure in surgical site infection management is expected to rise.1,14 Beyond the drawbacks of the general nonconcurrent cohort study design, other limitations to this study include the use of a single institution’s practice, unclear broad applicability to the current variety of surgical practices, and lack of randomization of treatments. As with many other group practices, there has been an incremental introduction of endovascular approaches to manage the types of patients included in this study, and this may be a source of potential bias. During the time course of this study, there was increased overall attention to surgical wound infections via initiatives such as the Institute for Health Care Improvement 100,000 Lives Campaign, and this certainly raises the possibility of confounding factors. However, the standard clinical perioperative practice (e.g., antibiotics) of the surgeons and providers in the current cohort did not change appreciably during the course of the study other than the dressing variable. Finally, there are
a host of factors (nutritional status, perioperative antibiotics and tissue oxygenation, etc.) that are known to impact incisional healing. The similarities between the two cohorts with regard to patient characteristics, operative indications, and procedure distribution, as well as there being no other known substantial changes in either the patient population or practice pattern, support general equivalence in these associated wound healing factors between the groups. However, the possibility of variation must be acknowledged, and future studies with this dressing system should record and control for these variables. The findings of this study are weakened by the variable duration of dressing application, the failure to report the wound contamination level at the time of dressing application, the presence or absence of remote sites of infection or open wounds at the time of surgery, and whether the patient experienced incontinence of urine or stool during the immediate postoperative period. Additionally, factors such as length of time dressings were left in place were not well standardized. All of these points may serve as useful data points and considerations in future studies of this dressing system. In summary, our findings provide clinical evidence that an Acticoat dressing system offers a potentially efficacious, cost-effective adjunct to reduce surgical site infections for lower extremity revascularization. Further investigation via multicenter case-controlled or randomized clinical trial may be warranted. REFERENCES 1. Mangram AJ, Horan TC, Pearson ML, et al. Guideline for prevention of surgical site Infection, 1999. Centers for
602 Childress et al.
2.
3.
4. 5.
6.
7.
Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee. Am J Infect Control 1999;27:97-132. Seal LA, Paul-Cheadle D. A systems approach to preoperative surgical patient skin preparation. Am J Infect Control 2004;32:57-62. Kent KC, Bartek S, Kuntz KM, et al. Prospective study of wound complications in continuous infrainguinal incisions after lower limb arterial reconstruction: incidence, risk factors, and cost. Surgery 1996;119:378-383. Mooney EK, Lippitt C, Friedman J. Silver dressings. Plast Reconstr Surg 2006;117:666-669. Tredget EE, Shankowsky HA, Groeneveld A, et al. A matchedpair, randomized study evaluating the efficacy and safety of Acticoat silver-coated dressing for the treatment of burn wounds. J Burn Care Rehabil 1998;19:531-537. Lansdown A, Williams A, Chandler S, et al. Silver dressings: absorption and antibacterial efficacy. Nurs Times 2005;101: 45-46. Khuri SF, Daley J, Henderson W, et al. The Department of Veterans Affairs’ NSQIP: the first national, validated, outcome-based, risk-adjusted, and peer-controlled program for the measurement and enhancement of the quality of surgical care. National VA Surgical Quality Improvement Program. Ann Surg 1998;228:491-507.
Annals of Vascular Surgery
8. Yin HQ, Langford R, Burrell RE. Comparative evaluation of the antimicrobial activity of Acticoat antimicrobial barrier dressing. J Burn Care Rehabil 1999;20:195-200. 9. Wright JB, Lam K, Burrell RE. Wound management in an era of increasing bacterial antibiotic resistance: a role for topical silver treatment. Am J Infect Control 1998;26: 572-577. 10. Ip M, Lui SL, Poon VK, et al. Antimicrobial activities of silver dressings: an in vitro comparison. J Med Microbiol 2006;55(Pt 1):59-63. 11. Strohal R, Schelling M, Takacs M, et al. Nanocrystalline silver dressings as an efficient anti-MRSA barrier: a new solution to an increasing problem. J Hosp Infect 2005;60: 226-230. 12. Thomas S, McCubbin P. A comparison of the antimicrobial effects of four silver-containing dressings on three organisms. J Wound Care 2003;12:101-107. 13. Kirkland KB, Briggs JP, Trivette SL, et al. The impact of surgical-site infections in the 1990s: attributable mortality, excess length of hospitalization, and extra costs. Infect Control Hosp Epidemiol 1999;20:725-730. 14. National Nosocomial Infections Surveillance (NNIS) System Report. Data summary from January 1992 through June 2004, issued October 2004. Am J Infect Control 2004;32: 470-485.
Surgical wounds for lower extremity revascularization are prone to infection and dehiscence. Acticoat AbsorbentÒ, an antimicrobial dressing, offers sustained release of ionic silver. We hypothesized that immediate application of Acticoat as a postoperative dressing would reduce wound complications in patients undergoing leg revascularization. All infrainguinal revascularization cases involving leg incisions at a single Veterans Administration Medical Center were identified from July 1, 2002, to September 30, 2005. The control group received conventional dressings, while the treatment group received an Acticoat dressing. Wound complication rates were captured via National Surgical Quality Improvement Program data. Patient characteristics and procedure distributions were similar between groups. The wound complication rate fell 64% with utilization of the Acticoat-based dressing (control 14% [17/118], treatment 5% [7/130]; P ¼ 0.016). An Acticoat-based dressing system offers a potentially useful, cost-effective adjunct to reduce open surgical leg revascularization wound complications.
INTRODUCTION Approximately 27 million surgical procedures are performed annually in the United States.1 One of the most common postoperative complications is surgical site infection, which causes significant morbidity and health-care costs (estimated at $1.5 billion per year)2 among hospitalized patients.1 Surgical wounds for lower extremity revascularization are particularly prone to infection and dehiscence, with rates in some series as high as 44%.3 Currently, the Guideline for Prevention of Surgical Site Infection recommends the use of sterile dressing to 1 Veterans Affairs Office of Academic Affiliation, North Florida/ South Georgia Veterans Health System, Gainesville, FL. 2 Division of Vascular Surgery and Endovascular Therapy, University of Florida College of Medicine, Gainesville, FL. 3 Malcom Randall Veterans Administration Medical Center, Gainesville, FL.
Correspondence to: C. Keith Ozaki, M.D., Chief, Surgical Service (112), 1601 SW Archer Road, Gainesville, FL 32608, USA, E-mail: [email protected] Ann Vasc Surg 2007; 21: 598-602 DOI: 10.1016/j.avsg.2007.03.024 Ó Annals of Vascular Surgery Inc. Published online: May 23, 2007
598
protect closed incisions for 24-48 hr postoperatively.1 However, no evidence-based recommendations are made with regard to dressing types for use in postoperative incision care. A plethora of wound dressings are available on the market, with silver-based dressing among recent innovations. Topical silver is an effective bactericidal agent that does not induce bacterial resistance when used at therapeutic levels.4 Acticoat AbsorbentÒ (Smith and Nephew, London, UK), an antimicrobial barrier dressing, is coated with nanocrystalline silver that delivers a controlled, sustained (up to 3 days) dose of silver ions. Additionally, this dressing absorbs moisture (minimizing wound maceration) and is safe and effective against a broad range of microorganisms. Acticoat is indicated for chronic wounds and burn wounds;5,6 however, data are lacking regarding its potential role in postoperative surgical incision wound infection prophylaxis. Therefore, we hypothesized that immediate application of Acticoat in conjunction with an overlying occlusive dressing as a postoperative dressing would reduce closed incisional wound complications in patients undergoing lower extremity revascularization involving infrainguinal skin incisions.
Vol. 21, No. 5, 2007
Acticoat dressing for lower extremity revascularization
599
Using a nonconcurrent cohort study design and real-time clinical data collection, we compared patients who received conventional non-silvercontaining dressing with Acticoat as a postoperative dressing following defined lower extremity revascularization.
MATERIALS AND METHODS Sample Selection Appropriate institutional approval was secured for this study, which includes all open lower extremity revascularization patients from over a 39-month study period at a single Veterans Administration Medical Center. Conventional non-silvercontaining dressings (typically sterile cotton gauze, often in combination with an overlying occlusive plastic dressing) were utilized over the first 15 months of the study. Beginning with the sixteenth month, all closed incisions were dressed with Acticoat and an occlusive plastic dressing (Fig. 1). Adherence of the occlusive plastic was facilitated by use of an alcohol-based prep solution immediately before final bandage application. The clinical practice of the group was to leave the immediate postoperative dressing in place until it was grossly contaminated with fluid or remove it electively between postoperative days 2 and 4. All open lower extremity revascularization cases from July 1, 2002, to September 30, 2005, were identified by Current Procedural Terminology (CPT) codes from a prospectively collected relational database. No cases were excluded. Cases involving more than one of these procedures were listed once based on the quantity of surgical wound at risk for complication. For instance, a case involving a concurrent ileofemoral and femoral-to-anterior tibial bypass would be listed as an infrainguinal bypass.
Fig. 1. Acticoat postsurgery.
dressing
applied
immediately
Data Collection Clinical data (age at the time of procedure, gender, race [white versus nonwhite], history of diabetes, diagnosis of hypertension, current smoking practice, and procedural indications) were abstracted from patient medical records. Wound complications (failure to heal [wound dehiscence], superficial and deep soft tissue infections) were defined using the National Surgical Quality Improvement Program (NSQIP) criteria7 and captured via the NSQIP. Locally, the study center’s NSQIP data entry is facilitated by first-pass contribution of information entered in real time into a vascular surgery-specific
database by the attending surgeons. The clinical practice of the group was to manage the large majority of infections with empiric antibiotic coverage including drainage and debridement as needed; thus, microbiological profiles of the wounds are not available. Statistical Analysis Chi-squared analysis was performed to compare patient characteristics for categorical data, and independent samples t-tests were used for continuous variables using SPSS 14.0 for Windows software
600 Childress et al.
Annals of Vascular Surgery
(SPSS, Chicago, IL). Level of statistical significance was evaluated at P < 0.05.
Table I. Patient characteristics
RESULTS
Age (mean years ± SD) Male gender Race (white) Diabetes Hypertension Current smoking Creatinine >1.5 mg/L
The study population comprised 216 patients who underwent 248 cases that met inclusion criteria (Table I). Both groups were similar with regard to age at the time of first procedure, gender, race, diabetes, hypertension, current smoking, and renal insufficiency (creatinine >1.5 mg/L). Both groups had tissue loss as the most common indication for the lower extremity revascularization procedure, with 47% (55/118) for the control group and 38% (49/130) for the treatment group (Table II). Moreover, autogenous vein bypass graft was the most common procedure performed for the control (65/118, 55% of procedures) and treatment (54/130, 42% of procedures) groups (Table III). The surgeons and other providers found the dressing regimen easy to apply and care for postoperatively. Revascularization pulses could be palpated through the dressing, and the low profile permitted identification of postoperative soft tissue changes such as hematomas. Compressive Ace bandages could be applied without disturbing the original dressing. No substantial dressing material-specific complications were noted, including any apparent allergic reactions. The wound complication rate for the control group was 14% (17/118), and that for the treatment group was 5% (7/130) (Table III). Over the intervention phase, the wound overall complication rate fell by 64% (c2 ¼ 5.76, degrees of freedom ¼ 1, P ¼ 0.016).
DISCUSSION This single-institution, nonconcurrent cohort study suggests that an antimicrobial silver-eluting absorbent dressing held in place with an occlusive plastic bandage reduces lower extremity revascularization wound complications when applied immediately postsurgery. This is consistent with previous efficacy studies of silver-coated dressings in burn wounds and chronic wounds.5,6 The manufacturer claims immediate and sustained silver release from this material for up to 3 days. Consequently, this dressing kills a broad spectrum of bacteria within 30 min of application, including antibiotic-resistant strains of Pseudomonas, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant Enterococcus.8-12 The alginate component of this dressing material appeared to assist with early postoperative
Control group (n ¼ 99)
Treatment group (n ¼ 117)
65.8 ± 10 99 (100%) 80 (81%) 48 (49%) 77 (78%) 58 (59%) 13 (11%)
65.7 ± 10.8 115 (98%) 99 (85%) 55 (47%) 101 (86%) 59 (50%) 15 (12%)
No statistical difference between groups for all characteristics.
Table II. Operative indications
Indication Claudication Rest pain Tissue loss Failing bypass graft Acute leg ischemia Other
Control group (n ¼ 118)
Treatment group (n ¼ 130)
9 18 55 26 6 4
21 18 49 17 16 9
(8%) (15%) (47%) (22%) (5%) (3%)
(16%) (14%) (38%) (13%) (12%) (7%)
wound hygiene, absorbing fluid that wept from the incision, thus avoiding the skin maceration occasionally seen with other less absorbent materials. The patient demographics, clinical characteristics, and open revascularization approaches appear representative of a typical Veterans Administration vascular surgical patient population, though the male dominance of the group distinguishes it from a civilian practice. The infrainguinal open procedures for arterial revascularization were selected a priori based on the literature and the authors’ direct observation of higher wound complications in this patient subset. These broader inclusion criteria also avoided the potential Type II error that might have been associated with a more select study population from a single institution. The low rate of surgical interventions for claudication and the rare use of prosthetic conduits may not mirror all contemporary surgical practices. The observed wound complication rates compare favorably with the published benchmark.3 In an economic costs study among 255 patients with surgical site infection who were matched to noninfected patients, the total extra costs attributable to surgical site infection were almost $2 million.13 For vascular surgery alone, the median total direct cost for 11 infected patients was $12,261 and that for uninfected patients was $6,666 in 1999 ($5,595 direct cost differential).
Vol. 21, No. 5, 2007
Acticoat dressing for lower extremity revascularization
601
Table III. Procedure distribution and wound complication rates Wound complication
Procedure Vein bypass graft Revision vein graft Aortobifemoral bypass Femoral reconstruction Axillary-bifemoral/femoral-femoral bypass Ileofemoral bypass Thromboembolectomy Prosthetic bypass graft Other Overall wound complication
Control group (n ¼ 118)
Treatment group (n ¼ 130)
13/65 0/12 1/13 1/6 0/5 1/6 0/4 0/5 1/2 17/118
4/54 0/11 2/21 0/10 1/13 0/5 0/5 0/7 0/4 7/130
(20%) (0%) (8%) (17%) (0%) (17%) (0%) (0%) (50%) (14%)
(7%) (0%) (10%) (0%) (8%) (0%) (0%) (0%) (0%) (5%)*
*P ¼ 0.016 vs. control group.
Furthermore, the median total length of hospital stay for infected vascular surgical patients was 24, while that for the uninfected was 8, days. The current cost to our hospital for a single 4 x 5 inch piece of the Acticoat material and the overlying occlusive plastic is approximately $10. Based on the results of this small study, the number of patients needed to treat with this silver-based dressing system to prevent one wound complication is approximately 11. Put simply, a $110 investment not only saves the individual morbidity of a wound complication but offers a substantial overall direct health-care system cost benefit based on an estimated cost of $5,595 per wound infection. With the alarming increase in antimicrobial resistance and the growing number of surgical patients who are elderly with comorbid diseases, the total expenditure in surgical site infection management is expected to rise.1,14 Beyond the drawbacks of the general nonconcurrent cohort study design, other limitations to this study include the use of a single institution’s practice, unclear broad applicability to the current variety of surgical practices, and lack of randomization of treatments. As with many other group practices, there has been an incremental introduction of endovascular approaches to manage the types of patients included in this study, and this may be a source of potential bias. During the time course of this study, there was increased overall attention to surgical wound infections via initiatives such as the Institute for Health Care Improvement 100,000 Lives Campaign, and this certainly raises the possibility of confounding factors. However, the standard clinical perioperative practice (e.g., antibiotics) of the surgeons and providers in the current cohort did not change appreciably during the course of the study other than the dressing variable. Finally, there are
a host of factors (nutritional status, perioperative antibiotics and tissue oxygenation, etc.) that are known to impact incisional healing. The similarities between the two cohorts with regard to patient characteristics, operative indications, and procedure distribution, as well as there being no other known substantial changes in either the patient population or practice pattern, support general equivalence in these associated wound healing factors between the groups. However, the possibility of variation must be acknowledged, and future studies with this dressing system should record and control for these variables. The findings of this study are weakened by the variable duration of dressing application, the failure to report the wound contamination level at the time of dressing application, the presence or absence of remote sites of infection or open wounds at the time of surgery, and whether the patient experienced incontinence of urine or stool during the immediate postoperative period. Additionally, factors such as length of time dressings were left in place were not well standardized. All of these points may serve as useful data points and considerations in future studies of this dressing system. In summary, our findings provide clinical evidence that an Acticoat dressing system offers a potentially efficacious, cost-effective adjunct to reduce surgical site infections for lower extremity revascularization. Further investigation via multicenter case-controlled or randomized clinical trial may be warranted. REFERENCES 1. Mangram AJ, Horan TC, Pearson ML, et al. Guideline for prevention of surgical site Infection, 1999. Centers for
602 Childress et al.
2.
3.
4. 5.
6.
7.
Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee. Am J Infect Control 1999;27:97-132. Seal LA, Paul-Cheadle D. A systems approach to preoperative surgical patient skin preparation. Am J Infect Control 2004;32:57-62. Kent KC, Bartek S, Kuntz KM, et al. Prospective study of wound complications in continuous infrainguinal incisions after lower limb arterial reconstruction: incidence, risk factors, and cost. Surgery 1996;119:378-383. Mooney EK, Lippitt C, Friedman J. Silver dressings. Plast Reconstr Surg 2006;117:666-669. Tredget EE, Shankowsky HA, Groeneveld A, et al. A matchedpair, randomized study evaluating the efficacy and safety of Acticoat silver-coated dressing for the treatment of burn wounds. J Burn Care Rehabil 1998;19:531-537. Lansdown A, Williams A, Chandler S, et al. Silver dressings: absorption and antibacterial efficacy. Nurs Times 2005;101: 45-46. Khuri SF, Daley J, Henderson W, et al. The Department of Veterans Affairs’ NSQIP: the first national, validated, outcome-based, risk-adjusted, and peer-controlled program for the measurement and enhancement of the quality of surgical care. National VA Surgical Quality Improvement Program. Ann Surg 1998;228:491-507.
Annals of Vascular Surgery
8. Yin HQ, Langford R, Burrell RE. Comparative evaluation of the antimicrobial activity of Acticoat antimicrobial barrier dressing. J Burn Care Rehabil 1999;20:195-200. 9. Wright JB, Lam K, Burrell RE. Wound management in an era of increasing bacterial antibiotic resistance: a role for topical silver treatment. Am J Infect Control 1998;26: 572-577. 10. Ip M, Lui SL, Poon VK, et al. Antimicrobial activities of silver dressings: an in vitro comparison. J Med Microbiol 2006;55(Pt 1):59-63. 11. Strohal R, Schelling M, Takacs M, et al. Nanocrystalline silver dressings as an efficient anti-MRSA barrier: a new solution to an increasing problem. J Hosp Infect 2005;60: 226-230. 12. Thomas S, McCubbin P. A comparison of the antimicrobial effects of four silver-containing dressings on three organisms. J Wound Care 2003;12:101-107. 13. Kirkland KB, Briggs JP, Trivette SL, et al. The impact of surgical-site infections in the 1990s: attributable mortality, excess length of hospitalization, and extra costs. Infect Control Hosp Epidemiol 1999;20:725-730. 14. National Nosocomial Infections Surveillance (NNIS) System Report. Data summary from January 1992 through June 2004, issued October 2004. Am J Infect Control 2004;32: 470-485.