Ann Thorac Surg 2003;75:101-105
© 2003 The Society of Thoracic Surgeons
Original article: cardiovascular
Occlusive wrap dressing reduces infection rate in saphenous vein harvest site
Franklin L. Rosenfeldt, FRACSa*,
Justin Negri, FRACSa,b,
Damien Holdaway, FRACSa,b,
Bruce B. Davis, FRACSa,b,
Julie Mack, BSa,b,
Michael J. Grigg, FRACSa,b,
Campbell Miles, FRACSa,b,
Donald S. Esmore, FRACSa,b
a Cardiac Surgical Research Unit, Department of Cardiothoracic Surgery, Alfred Hospital, Melbourne, Australia
b Cardiac Surgical Research Unit, Department of Vascular Surgery, Alfred Hospital, Melbourne, Victoria, Australia
Accepted for publication July 30, 2002.
* Address reprint requests to Dr Rosenfeldt, Department of Cardiothoracic Surgery, Alfred Hospital, Commercial Rd, Prahran 3181, Melbourne, Victoria, Australia.
e-mail: f.rosenfeldt{at}alfred.org.au
 |
Abstract
|
|---|
BACKGROUND: Infection in the saphenous vein harvest site is a common problem. We developed an occlusive circumferential wrap dressing technique that reduces skin edge tension, eliminates dead space, and prevents external contamination. We compared the surgical site infection rate using the wrap dressing technique with that of standard longitudinal dressings.
METHODS: One hundred fifty-two consecutive patients were randomly assigned to receive either standard dressings or the wrap dressing. Data were collected in the hospital and then 4 to 6 weeks postoperatively. Superficial and deep wound infections were defined by the standard criteria from the Centers for Disease Control and Prevention.
RESULTS: The infection rate in the wrap group was 14% compared with 35%, for the standard group (p = 0.006). Multivariate analysis showed that wrap technique was the only significant predictor (negative) of infection (odds ratio, 0.19; p = 0.001).
CONCLUSIONS: In saphenous vein harvest wounds, the occlusive wrap dressing technique has the potential to reduce the rate of infection by 50%. This simple and inexpensive technique is also readily applicable to the radial artery harvest site in the arm and may provide similar benefit.
|
Introduction
|
|---|
The saphenous vein harvest wound is well recognized as a frequent site of infectious complications [1]. Many studies have addressed methods of reducing the rate of infection, but most have focused on the method of closure [2, 3], the use of prophylactic antibiotics, or intraoperative wound lavage [4]. Few have focused on the management of the wound after closure as a method of reducing infection.
Saphenous vein harvest wounds are generally longer than most surgical incisions. Patients undergoing cardiac revascularization include many with multiple risk factors for wound infection, including obesity, diabetes, and occlusive arterial disease. When a long segment of vein is required, the incision is carried into the groin region where infection is more likely [5]. Often the harvest produces an undermined flap in which the skin incision fails to parallel the variable path of the saphenous vein. The weight of this flap places tension across the wound, which may lead to dehiscence. In addition a dead space may remain after wound closure, especially in the thigh of an obese patient. This allows a collection of fluid to form, which predisposes to infection.
We hypothesized that a broad, occlusive, polyurethane wrap would support, compress, and seal the wound and that if it were left intact for 10 days it would reduce therate of infection. We compared the infection rate using the wrap dressing with that observed with standard dressings.
|
Material and methods
|
|---|
Between January and July 1998, 152 consecutive patients were enrolled in the study. As the study was part of a quality assurance program for wound infections and only dressing techniques already in use were compared, informed consent was not obtained from the patients. Patients were randomly assigned to either the occlusive wrap dressing or a standard dressing by use of coded envelopes. Demographics including body mass index, the presence of diabetes, tobacco use (present or past), renal impairment (serum creatinine above the normal range), and concurrent corticosteroid use were recorded.
The following operative data were recorded: bypass time, the seniority of the surgeon who harvested the vein, whether a deep stitch was used, the distal extent and maximal depth of the wound, and whether a drain was used.
Surgical technique
Antibiotic prophylaxis continued for 24 hours was cephazolin, 1 g on induction of anesthesia, then every 8 hours for 24 hours. If the patient had been in the hospital for 3 or more days, then vancomycin, 1 g intravenously, was administered on induction of anesthesia, then every 12 hours for 48 hours. The harvest sites were closed with subcuticular sutures. The choice of a deeper subcutaneous stitch was left to the surgeon’s discretion.
In the wrap group, dressing commenced with a vigorous wash with aqueous chlorhexidine-cetrimide solution, after which the leg was wrapped in a series of 20-cm by 8-cm polyurethane adhesive strips (OpSite dressing, Smith and Nephew, Clayton, Melbourne, Australia). The strips were applied firmly from posterior to anterior to support the posterior wound edge beginning distally (Fig 1).
The dressing covered only 60% to 70% of the circumference of the leg to prevent distal swelling. Each strip had a 20% overlap with the adjacent strip. The dressings were left intact for a minimum of 10 days (unless they were soiled or lost contact with the skin) and then usually removed by the patient after leaving the hospital.
View larger version (25K):
[in this window]
[in a new window]
|
Fig 1. Application of adhesive dressing strips under tension posteriorly to anteriorly to support the wound.
|
|
Standard dressings consisted of a normal saline wash then either a dry nonstick cotton acrylic pad mounted on adhesive sterile paper (Primapore, Smith and Nephew, Clayton, Victoria, Australia), transparent, adhesive film (Tegaderm, 3M Health Care, St Paul, MN), or flexible, absorbent gel (Duo Derm, Bristol-Meyers Squibb Canada Inc, Montreal, Quebec, Canada). All these standard dressings were placed longitudinally and were supported for 24 hours by cotton wool and a crepe bandage. These dressings were removed shortly before the patient left the hospital. Patients were allowed to shower as soon as they were fit to do so regardless of the type of dressing.
The Centers for Disease Control and Prevention (CDC) definition of a superficial wound infection was that it involved only the skin or subcutaneous tissue with at least one of the following: purulent discharge; an organism isolated on microbiological swab; or some sign of inflammation, ie,: tenderness, swelling, erythema, heat, or surgical intervention (the incision was reopened). Deep wound infection involved the deep tissues and at least one of the following: purulent discharge; abscess formation; spontaneous dehiscence; or surgical intervention. Finally, according to the CDC definition, the diagnosis of infection could be made at the surgeon’s discretion. At follow-up the surgeon had no knowledge of the group to which the patient had been assigned.
Wounds were assessed until discharge and then in the outpatient department after 4 to 6 weeks. Those who did not attend the outpatient department were followed up with a combination of telephone interview and a questionnaire to their local medical practitioner. All patients identified as having wound infection had their microbiological and medical records reviewed, and data were checked by the infection control department.
Statistical methods
Values given are mean ± standard error of the mean unless otherwise stated. The Student’s t test was used for parametric data, the Wilcoxon test for nonparametric data, and the 
2 and Fisher’s exact test for categorical data. Infected and noninfected groups were compared to identify univariate predictors of infection. Significant univariate predictors were then entered into a multivariate, stepwise, logistic regression analysis. This was initially done as a forward procedure and then validated by a backward procedure. Statistical significance was defined as a p value less than 0.05.
|
Results
|
|---|
Seventy-two patients had wrap dressings and 78 had standard dressings. There were no significant demographic differences between the two groups (Table 1).
Operative data were also similar (Table 2).
Follow-up was 99% complete with 65% assessed in the outpatient department and 35% by telephone survey. The infection rate in the wrap group (14%) was less than half that in the standard group (35%; p = 0.006; Table 3).
Of the total of 27 infections, only one (in the control group) was detected in the hospital; the remainder were diagnosed after discharge from hospital. All infected patients received either oral or intravenous antibiotics. Three patients (2%) had infections serious enough to warrant further surgical procedures, one being debridement and two requiring skin grafts. Two of these patients had received standard dressings and one the wrap.
In the wrap group 80% of infections were culture positive. Of the causative organisms 50% were methicillin-resistant Staphylococcus aureus, 50% methicillin-sensitive S aureus, and none were gram-negative. In the standard group 85% of wounds were culture positive: 39% grew methicillin-resistant S aureus, 22% methicillin-sensitive S aureus, and 39% other organisms, predominantly gram-negative.
Univariate analysis of infection both on demographic and operative data indicated wrap, wound depth, and diabetes were significant predictors of infection (Table 4).
Multivariate analysis showed the use of the wrap was the only significant, independent, negative determinant of infection with an odds ratio of 0.19 (p = 0.001; Table 5).
|
Comment
|
|---|
This study showed a high incidence of leg wound infections in saphenous vein harvest sites according to the CDC definition and that the infection rate could be reduced substantially and gram-negative sepsis eliminated by an occlusive wrap dressing technique. This inexpensive and novel dressing technique is now also routinely applied in our unit to the radial artery harvest site in the upper limb as well as the saphenous vein site.
It is generally believed that different dressings have little effect on the outcome of a clean surgical wound. This is true when the wound is likely to heal primarily because if the infection rate is low it is difficult to demonstrate any gains with one dressing type over another. Consequently most reports focus on other issues such as the ease of a dressing change or the number of dressings and the pain involved [6]. However in the case of saphenous vein harvest wounds, comparison of wound dressings may reveal differences in outcomes owing to the high rate of infections and other problems specific to these wounds.
One study similar to ours is that by Angelini and associates [7], comparing four types of skin closure: clips, nylon mattress sutures, subcuticular sutures, or sutureless adhesive dressing. In keeping with the problematic nature of this wound, only 44% were well healed by the 10th postoperative day. The adhesive dressing closure caused no difference in the rate of infection but achieved an improvement in cosmetic result.
Mechanism of action of wrap technique
We postulate that the wrap works by a combination of three mechanisms. First, it supports the wound by opposing distracting forces on the wound edges. These forces occur as a result of the gain in tissue volume after capillary leak as a result of the systemic inflammatory response triggered during cardiopulmonary bypass. The wrap reduces tension by providing broad-based support for the skin edge to facilitate apposition and prevent dehiscence (Fig 2).
Second, the wrap provides compression. This reduces the accumulation of fluid in the subcutaneous plane. Third, the membrane seals the wound area and protects the wound from secondary inoculation. The wound edges are often not sealed within 48 hours and are exposed to direct contamination, especially when the proximal harvest sites were the inguinal area, a fertile site for colonization with gram-negative organisms. That no gram-negative infection occurred in the wrap group is in accordance with a sealing action of the wrap. An important component of the wrap technique was the vigorous washing of the wound edges with aqueous chlorhexidine and cetrimide before applying the dressing. This procedure was designed to ensure that the entire surface underlying the occlusive dressing was sterile at the moment of application of the dressing. Chlorhexidine sterilizes the wound surface, and cetrimide has a detergent action, which removes fat residues from the skin that can prevent adhesion of the wrap. An additional benefit of the polyurethane strips over most other dressings is that they are transparent. This allows the wound to be checked for signs of exudation, bleeding, or dehiscence without removing the dressing.
View larger version (44K):
[in this window]
[in a new window]
|
Fig 2. Mechanisms of action of the dressing: (left) apposition of wound edges supporting the suture line; (middle) compression of the tissue to eliminate dead space and prevent accumulation of fluid; (right) sealing of the wound area to prevent secondary inoculation.
|
|
Critical evaluation
In the study by Mullen and colleagues [2], wound depth was a significant predictor of infection. Diabetes is the major risk factor in most studies of wound infection. In the present study diabetes and wound depth were univariate predictors of infection but fell short of statistical significance on multivariate analysis.
The infection rate for surgical procedures is highly dependent on the definition of infection adopted. Published infection rates from saphenous vein harvest vary from 1% to 44% [1]. Infection rates are also affected by the length of follow-up. In the study by Johnson and coworkers [8], the peak incidence of wound infection occurred 4 weeks after operation. Not all studies follow the patient until the wound has healed or even beyond the in-hospital stay, which would produce a spuriously low infection rate. In a previous study from our institution, 58% of infections were identified after discharge [9]. In the present study we found that 97% of infections were detected after the patient had been discharged from the hospital. Only 1 patient (a control group patient), had an infection documented while in the hospital, ie, 3% of the combined groups.
Different definitions of infection cause difficulties in comparing complication rates among different institutions. In many cases local wound problems such as skin edge necrosis, noninfective serous discharge, or simple local dehiscence may not be counted as infections. To overcome this some authors use descriptive terms such as class 1, lymph leak, or skin edge necrosis; class 2, infection or necrosis; and class 3, perigraft infection [1]. Other end points used are any discharge (infective or not) or simply failure of the wound to heal completely [8]. Our rate of infection appears unacceptably high, but we believe that this can be explained in part by our use of the broad CDC definition of infection. To confirm this we reanalyzed our data using the narrower definition currently used by the Australian Council of Health Care Standards. This simpler definition includes only wounds from which purulent material drains on or after the fifth postoperative day and excludes a tissue reaction around the suture material, which could be included in the CDC definition. This reanalysis reduced the rate of infection from 14% to 11% in the wrap group and from 35% to 27% in the control group. The difference in infection rate between the wrap and the control groups remained significant (p = 0.025).
Economics of infection
The economic impact of infection and inconvenience for patients are probably greater than the clinical morbidity suggests. Only a minority of wound infections requires reoperation, and infection of the saphenous harvest site rarely causes death. However, the regular dressings and ongoing antibiotic use often means a long hospital stay and protracted outpatient medical care. Nelson and Dries [10] noted that wound infections including the sternum and the leg increased the average length of stay by 16.7 days and increased the cost per patient by $8,118.
Conclusions
The broad-based CDC definitions for wound infection and prolonged postoperative surveillance can produce a higher infection rate in saphenous vein harvest wounds than with more narrow definitions and inpatient surveillance alone. The simple intervention of using an occlusive polyurethane wrap can significantly reduce infection in the saphenous vein harvest site. This technique, which is readily applicable to the radial artery wound in the arm, should produce similar benefits to those seen in the leg.
|
Acknowledgments
|
|---|
We thank Carol M. and Ian G. Clarke for financial assistance and Smith and Nephew for their donation of OpSite dressings for this study. We thank the operating room nurses for their assistance. We acknowledge the statistical assistance of Michael Bailey in the Department of Epidemiology and Preventative Medicine, Monash University, Melbourne; and the advice of Denis Spelman, MD, Department of Infectious Diseases, Alfred Hospital, Melbourne, Victoria, Australia.
|
References
|
|---|
- Reifsnyder T., Bandyk D., Seabrook G., Kinney E., Towne J.B. Wound complications of the in situ saphenous vein bypass technique. J Vasc Surg 1992;15:843-850.[Medline]
- Mullen J.C., Bentley M.J., Mong K., et al. Reduction of leg wound infections following coronary artery bypass surgery. Can J Cardiol 1999;15:65-68.[Medline]
- Corder A.P., Schache D.J., Farquharson S.M., Tristram S. Wound infection following high saphenous ligation. A trial comparing two skin closure techniques: subcuticular polyglycolic acid and interrupted monofilament nylon mattress sutures. J R Coll Surg Edinb 1991;36:100-102.[Medline]
- Wong S.W., Fernando D., Grant P. Leg wound infections associated with coronary revascularization. Aust N Z J Surg 1997;76:689-691.
- Lorentzen J.E., Nielsen O.M., Arendrup H., et al. Vascular graft infection: an analysis of sixty two graft infections in 2411 consecutively planted synthetic vascular grafts. Surgery 1985;98:81-86.[Medline]
- Rasmussen H, Larsen MJ, Skeie E. Surgical wound dressing in outpatient paediatric surgery: a randomised study. Danish Med Bull 1993;40:252–4
- Angelini G.D., Butchart E.G., Armistead S.H., Breckenridge I.M. Comparative study of leg wound skin closure in coronary artery bypass graft operations. Thorax 1984;39:942-945.[Abstract/Free Full Text]
- Johnson R.G., Cohn W.E., Thurer R.L., McCarthy J.R., Sirois C.A., Weintraub R.M. Cutaneous closure after cardiac operations. Ann Surg 1997;226:606-612.[Medline]
- Kent P., McDonald M., Harris O., Mason T., Spelman D. Post-discharge surgical wound infection surveillance in a provincial hospital: follow-up rates, validity of data and review of the literature. Aust N Z J Surg 2001;71:583-589.
- Nelson R.M., Dries D.J. The economic implications of infection in cardiac surgery. Ann Thorac Surg 1986;42:240-246.[Abstract]
This article has been cited by other articles:
|
|
|
|
 
C. K L Ho, M. P. Sun, T. W K Au, and C. S W Chiu
Pneumatic Pump Reduces Leg Wound Complications in Cardiac Patients
Asian Cardiovasc Thorac Ann,
December 1, 2006;
14(6):
452 - 457.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. Wynne, M. Botti, H. Stedman, L. Holsworth, M. Harinos, O. Flavell, and C. Manterfield
Effect of Three Wound Dressings on Infection, Healing Comfort, and Cost in Patients With Sternotomy Wounds: A Randomized Trial
Chest,
January 1, 2004;
125(1):
43 - 49.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
