Healing Outcomes and Predictors of Postoperative Sternal Wound Infections via Median Sternotomy Following Cardiac Surgery: A Comparative Retrospective Case-Control Study

Abstract

Background: Surgical wound infection (SWI) following cardiac surgery via median sternotomy remains a serious complication associated with significant morbidity, prolonged hospitalisation, and increased healthcare costs. Mediastinitis and superficial sternal wound infections represent a spectrum of postoperative complications that adversely affect patient outcomes.

Aim of the Study: This study aimed to assess the healing outcomes and predictors of mediastinitis and superficial sternal wound infections after cardiac surgery.

Patients and Methods: This retrospective case-control study was conducted at the Cardiothoracic Surgery Departments of Shebein Elkom Teaching Hospital and National Heart Institute. A total of 100 adult patients who underwent cardiac surgery via median sternotomy were enrolled and divided into two groups: Group I (SWI group, n = 50) comprising patients who developed surgical wound infection, and Group II (Non-SWI group, n = 50) comprising patients who did not develop SWI.

Results: Patients in the SWI group were significantly older and had higher body mass index compared to the non-SWI group. Diabetes mellitus was significantly more prevalent in the SWI group. SWI group had significantly lower preoperative hemoglobin and albumin and significantly higher white blood cell count and serum creatinine. The SWI group had significantly longer operation time, cardiopulmonary bypass time, duration of mechanical ventilation, ICU stay and total hospital stay. Postoperative mediastinitis occurred in 30.0% of SWI patients, wound dehiscence in 56.0%, clinical erythema in 86.0%, and clinical discharge in 86.0%. All SWI patients had positive wound cultures; the most frequently isolated organisms were coagulase-negative staphylococci (26.0%) and methicillin-sensitive Staphylococcus aureus (26.0%), followed by Pseudomonas aeruginosa (16.0%) and mixed bacterial flora (14.0%). All patients received antibiotics; management included regular dressing (80.0%), surgical debridement (42.0%), negative pressure wound therapy (38.0%), and muscle flap reconstruction (6.0%). The mean time to SWI diagnosis was 13.14 ± 6.08 days postoperatively, with 70.0% classified as superficial infections and 90.0% achieving complete healing within 90 days. Multivariate logistic regression identified body mass index (p = 0.006), diabetes mellitus (p = 0.007), preoperative albumin (p = 0.002), and operation duration (p = 0.001) as independent predictors of SWI.

Conclusion: Surgical wound infection after cardiac surgery via median sternotomy is associated with significant patient morbidity and prolonged recovery. Higher body mass index, diabetes mellitus, preoperative hypoalbuminaemia, and prolonged operation duration are independent predictors of SWI. Preoperative optimisation of nutritional status, glycaemic control, and meticulous intraoperative time management are essential preventive strategies.