Cath Lab Digest

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Index: Ostomy Wound Manage. 2008;54(10):36-41.

Abstract

  Mediastinitis is a rare but serious postoperative complication of cardiac surgery that increases mortality rates, hospital length of stay, and medical costs. A clinical trial was conducted to investigate whether the type of postoperative surgical dressing (silver nylon or standard gauze) affects the rate of mediastinal infections. The sample consisted of 1,600 surgical cardiac patients.Infection rates in the standard gauze group (control, n = 1,235) were collected retrospectively from 24 months of infection control records. In the prospective treatment arm of the study, the wounds of all consecutive surgical patients (n = 365) were covered with a silver nylon dressing and patients were assessed during the 3-week postoperative visit. Thirteen (13) patients in the control group (1%) and none of the patients in the treatment group developed mediastinitis (chi² [1, N = 1,600] = 3.88, P <0.05). Study findings support the need for a large, prospective, controlled clinical study to confirm the effects of these dressings on mediastinitis, resultant morbidity, and costs of care.

KEYWORDS: silver nylon fabric, mediastinitis, mediastinum infections

     Although uncommon, mediastinitis is a serious postoperative complication associated with many negative outcomes. Methicillin-susceptible Staphylococcus aureus, Gram-negative bacilli, and methicillin-resistant S. aureus are three strains of bacteria most commonly associated with mediastinitis.^1,2 The occurrence of mediastinal infections varies but has been reported to be between .04% and 5.0%.^1,3 Heart transplant patients have the greatest risk for developing mediastinitis when compared to other cardiac procedures, with rates ranging between 2.5% and 6.0%.⁴ Mortality rates, hospital stays, and medical costs increase considerably for patients who develop this infection.^5-7 Mortality rates for patients who develop mediastinitis after undergoing any cardiac procedure increase by an average of 10% to 20%⁸ and can be as high as 47%.⁹ Milano et al,¹⁰ after conducting a study involving 6,459 patients undergoing coronary bypass grafting (CABG), report that early debridement and delayed closure can decrease mortality rates to less than 20%. Medical costs and hospital stays have been found to increase with the development of mediastinitis, on average, by $20,000¹¹ and 12.2 days,¹² respectively.

     Many studies have identified preoperative risk factors that increase the risk of developing mediastinitis. These factors include smoking, obesity, vascular disease, longer stays in the intensive care unit, infections at other sites, diabetes, and hypertension.^13-16 Additional studies^17,18 have shown the benefits of using different postoperative care techniques to reduce mediastinitis, including incision closure with rigid fixation and the application of topical bacitracin ointment. Song et al18 showed a significant reduction in the incidence of mediastinitis when rigid plate fixation rather than wire-circlage was utilized for sternotomy closure. None of the patients in the prospective rigid plate fixation study group (n = 45) developed mediastinitis compared to 28 cases reported in the retrospective, wire-closed control group. In 2006, MacIver et al17 investigated the impact of topical bacitracin ointment on mediastinitis development in patients who underwent sternotomy incisions for valvar and ischemic heart disease.