Ann Thorac Surg 2005;80:2162-2165
© 2005 The Society of Thoracic Surgeons
Original article: Cardiovascular
Single-Layer Versus Multiple-Layer Closure of Leg Wounds After Long Saphenous Vein Harvest: A Prospective Randomized Trial
Muhammed Zafar, PhD,
Anil John, FRCS
*
,
Zahid Khan, FRCS,
Simon M. Allen, FRCS,
Adrian J. Marchbank, FRCS,
C. Terence Lewis, FRCS,
Malcolm J.R. Dalrymple-Hay, PhD, FRCS,
James Kuo, FRCS,
Jonathan Unsworth-White, FRCS
Southwest Cardiothoracic Centre, Division of Cardiothoracic Surgery, Derriford Hospital, Plymouth, United Kingdom
Accepted for publication May 16, 2005.
* Address correspondence to Dr John, Southwest Cardiothoracic Centre, Division of Cardiothoracic Surgery, Derriford Hospital, Plymouth PL6 8DH, UK (Email: ajohn234{at}hotmail.com).
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Abstract
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BACKGROUND: The long saphenous vein harvested by traditional techniques is an important conduit for coronary artery bypass grafting (CABG). The purpose of this study was to determine if a single-layer closure over a drain improved wound healing compared with the traditional two-layer closure after harvest.
METHODS: Seventy-eight consecutive patients undergoing CABG were prospectively randomized to have their leg wound closed by either a single-layer technique with a suction drain or multiple layers. All wounds were assessed using the additional treatment, presence of serous discharge, erythema, purulent exudate, and separation of the deep tissues, isolation of bacteria, and the duration of inpatient stay (ASEPSIS) score postoperatively and 6 weeks later.
RESULTS: Forty-four patients (5 females) had their wound closed by the single-layer technique and 34 (6 females) closed in multiple layers. The ASEPSIS scores were significantly lower (p = 0.001) in those patients closed with a single layer (mean, 4.4) than those with multiple layers (mean, 6.8). Patients whose legs were closed with the single-layer technique had less peripheral edema compared with the multiple-layer group (
2, p < 0.001). Using univariate analysis there was no correlation between ASEPSIS scores and length of wound incision (p = 0.49), whereas increasing age was found to have a weak positive correlation (r =0.24; p = 0.04).
CONCLUSIONS: Single-layer leg wound closure over a suction drain is superior to the traditional multiple-layer closure. A possible mechanism of better wound healing in the former technique might be through decreased tissue handling and a reduction in leg edema.
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Introduction
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Coronary artery bypass grafting is a very common operation with highly successful outcomes but wound complications from harvesting the long saphenous vein can be a major source of postoperative morbidity. Poor wound healing after harvest often increases the length of hospital stay and the overall cost of treatment [1].
Despite the increased use of arterial grafts, the long saphenous vein remains the most frequently used conduit for coronary revascularization. Standard technique for harvesting the saphenous vein usually involves a long continuous open skin incision, with harvest of the entire length often necessary for multiple grafts. Complications from wound healing can often be protracted; unfortunately, harvesting of the venous conduit from the leg is often delegated to a junior and possibly less experienced member of the surgical team.
Leg wound complications have been reported to occur in 2% to 24% of cases [2–5]. One large series involving 3,525 patients undergoing coronary artery bypass grafting over a 10-year period reported an average complication rate of 4.2% [6]. Surprisingly, over the years little attention has been paid to the morbidity arising from leg wound complications in coronary artery bypass grafting operations and in particular to the best method of skin closure after an open harvest technique. The purpose of this randomized trial was to compare two methods of leg wound closure; single-layer closure over a suction drain and the traditional multiple-layer closure.
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Patients and Methods
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Seventy-eight patients undergoing coronary artery bypass grafting at the Southwest Cardiothoracic Centre in Plymouth, United Kingdom, consented to take part in the trial. Eighty-six legs that had the long saphenous vein harvested were analyzed in this prospective randomized trial comparing two different methods of leg wound skin closure. In order to minimize differences in clinically significant variables between the two groups, we used a process of stratified randomization known as minimization. In this method first described in 1974 and further accorded the platinum standard for randomized trials [7], group allocation is designed to reduce any differences in the distribution of known or suspected determinants of outcome. Stratification variables included diabetes, peripheral vascular disease, and renal failure. A computer software program MINIM (MINIM Software, Plymouth, UK) was used for stratified randomization.
Patients were randomized into two treatment groups: single-layer or multiple layers. A surgeon performed all conduit vein harvests and closure of wounds. Beginning at the ankle the skin was incised sharply down to the level of the saphenous vein and the incision extended proximally, taking great care to avoid flaps. Fatty legs were not excluded and all incisions were of reasonably good quality. Leg incisions were closed while the patient was still on cardiopulmonary bypass and prior to reversal of anticoagulation. Single-layer closure was achieved by closing the skin with subcutaneous Vicryl (Ethicon Inc, Somerville, NJ) over a suction drain (HVS Medinorm S-150; Ch 8; Summit Medical Ltd, Gloucestershire, UK) after satisfactory hemostasis using ligature clips [8]. This prevacuum wound drainage system produces a high constant negative pressure (20 kPa). Depending on the length of the incision one to two drains were placed in the leg and thigh to drain the subcutaneous space. Multiple-layer closure involved, in addition, closing the subcutaneous fat layer with 2-0 Dexon (Tyco Healthcare UK Ltd, Hampshire, UK).
All wounds were covered with a nonocclusive surgical dressing and the leg was wrapped with an elastic bandage for 48 hours. Suction drains were removed after 24 hours and total drainage noted. As per our unit protocol for patients undergoing uncomplicated coronary artery bypass grafting, intravenous cephalosporin (Cefuroxime 750 mg at eight hour intervals) was administered for the first 48 hours in all patients.
Pus and the isolation of infecting organisms often define serious clinical wound infection. However, lesser degrees of wound infection as well as impaired healing are clinically important and contribute to the morbidity associated with coronary artery bypass grafting. In order to have an objective and reproducible method of assessment of leg wound healing we used the additional treatment, presence of serous discharge, erythema, purulent exudate, and separation of the deep tissues, isolation of bacteria, and duration of inpatient stay (ASEPSIS) scoring method [9]. Wounds were assessed every 48 hours until discharge and at 6 weeks in the clinic.
Statistical Analysis
Data were analyzed with the SPSS (version 11.5) software package (SPSS, Inc, Chicago, IL). The Student's t test was used for the statistical analysis of continuous variables . The 2 analysis was performed on categorical variables and Spearman's correlation coefficient was used to investigate associations between variables. Statistical significance was determined at a p value 0.05 or less.
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Results
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Of the 78 patients recruited for the study, 67 were male and 11 were female (single-layer closure, n = 5; multiple-layer closure, n = 6). The mean and standard deviation of the ages are given in Table 1; mean drainage into suction drains was 150 ± 40 mLs.
ASEPSIS Score
One of the main outcome variables was the total ASEPSIS score (Appendix). Eight patients (single layer, n = 2; multiple layer, n = 6) had veins harvested from both their legs. In these 8 patients the average of the ASEPSIS scores from both legs was used in the analysis. There was strong evidence of a difference (p = 0.001) between the treatments with the "single-layer closure with drain" having better (lower) scores on average (Table 2
and Fig 1).
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Fig 1. Mean and median additional treatment, presence of serous discharge, erythema, purulent exudate, and separation of the deep tissues, isolation of bacteria, and duration of inpatient stay (ASEPSIS) score by technique.
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Diabetic patients often have impaired wound healing, hence the ASEPSIS score can be expected to be higher in this subgroup of patients. In our study, 18 patients were diabetic (9 in each group; noninsulin dependent diabetes; n= 14; insulin dependent diabetes; n = 4).
Diabetic patients who had their leg wounds closed in a single layer had lower ASEPSIS scores compared with patients with multiple-layer closure, similar to the scoring trend in nondiabetic patients (p = 0.001). Wound length incisions (Table 3) were analyzed for correlation with ASEPSIS scores. There was no evidence of a difference in ASEPSIS scores between the groups with respect to incision lengths (p = 0.49).
There was a greater incidence of postoperative donor leg edema in the multiple-layer closure group compared with patients who had their wounds closed in a single layer over a suction drain (p < 0.001) (Table 4). There was a weak positive correlation between total ASEPSIS score and age (r = 0.24, p = 0.04) although there was no correlation between patient weight and ASEPSIS scores.
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Comment
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Despite the emerging trend for the use of arterial conduits for revascularization, most patients undergoing coronary artery bypass grafting have single or multiple lengths of long saphenous vein harvested for grafting by the open technique. Impaired wound healing may contribute to a prolonged hospital stay, readmission, and the use of antibiotics .It can reduce the quality of a patient's life after otherwise uncomplicated coronary artery bypass grafting. It is therefore important that proper surgical technique and methods to improve wound healing are explored and used. Surgical wound closure should result in accurate apposition of wound edges until healing begins [10]. From the patient's point of view the wound should also be painless and cosmetically acceptable.
In most previous studies [11, 12] diabetes has been demonstrated to be a risk factor for wound infection after cardiac surgery. Diabetic patients have a higher incidence of peripheral vascular disease and impaired neutrophil function. The combination of macrovascular and microvascular disease with impaired cellular defense mechanisms predisposes diabetic patients to impaired wound healing. In our study diabetic patients who had their leg wound closed with a single layer had lower ASEPSIS scores compared with diabetics in the multiple-layer group.
In addition, patients who had their wounds closed in a single layer over a drain had less postoperative edema in the donor leg compared with the conventional method of leg wound closure. This can be attributed to decreased dead space due to evacuation of the hematoma and minimal tissue handling when using the single-layer closure technique. We do not use electrocautery for hemostasis, which in addition limits tissue injury and subcutaneous debris. Studies have shown lower wound complication rates with endoscopic vein harvest techniques [13, 14]. These techniques have financial implications, a learning curve, and longer harvest times [15].
In an era of endoscopic vein harvests many centers around the world still use the open harvest technique. Our study shows the superiority of single-layer closure with a suction drain over the more traditional multiple-layer approach in the promotion of leg wound healing, probably due to a combination of less tissue handling and decreased postoperative edema.
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Appendix
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References
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- Peacock EE, Van Winkle HW. Surgery and biology of wound repair. Philadelphia, PA: Saunders; 1970. pp. 184.
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- Kiaii B, Moon BC, Massel D, et al. A prospective randomized trial of endoscopic versus conventional harvesting of the saphenous vein in coronary artery bypass surgery J Thorac Cardiovasc Surg 2002;123:204-212.[Abstract/Free Full Text]
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- Schurr UP, Lachat ML, Reuthebuch O, et al. Endoscopic saphenous vein harvesting for CABG—a randomized, prospective trial Thorac Cardiovasc Surg 2002;50:160-163.[Medline]
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Abstract
Introduction
