Sternal Wound InfectionEdit
Sternal wound infection is a serious postoperative complication that can follow sternotomy in cardiac surgery. It ranges from superficial infection of the incision to deep sternal wound infection, sometimes extending into the mediastinum (mediastinitis). The condition imposes substantial risk of morbidity and death if not recognized and treated promptly, and it poses difficult questions about the best balance between aggressive surgical intervention and antibiotic therapy. Because prevention, rapid diagnosis, and decisive management save lives and control costs, SWI is a frequent focus of quality improvement in surgical practice.
From a practical, outcomes-oriented standpoint, the core measure of success is timely acceleration from suspicion to definitive treatment. This typically means immediate surgical consult, rapid debridement when indicated, and targeted antibiotic therapy guided by culture results. The story of SWI is a reminder that good surgical technique, meticulous wound care, and efficient hospital processes matter as much as any single medicine or device.
Epidemiology
The incidence of SWI after sternotomy varies with patient risk and hospital experience, but modern cardiac centers report rates on the order of roughly 0.5% to a few percent. Risk factors cluster around patient health status, operative complexity, and perioperative management. Obesity, diabetes mellitus, chronic lung disease, smoking, malnutrition, and immunosuppression raise the likelihood of infection. Reoperation, prolonged chest-tube drainage, and longer operative times further increase risk. Center volume and adherence to infection-prevention protocols also influence outcomes.
Etiology and pathophysiology
SWI reflects infection of the sternotomy wound, with possible involvement of the mediastinal tissues when the infection is deep. The usual microbiology resembles that of other surgical site infections, with Staphylococcus aureus and coagulase-negative staphylococci among the most common pathogens, often in combination with gram-negative rods or anaerobes in polymicrobial cases. The skin and mucosal flora can seed the wound during or after surgery, particularly in patients with compromised healing. In many cases, especially where prosthetic material or sternal wires are involved, infection becomes entrenched in dead space and hardware, making source control more challenging.
For understanding the microbiology and treatment, see Staphylococcus aureus and Coagulase-negative staphylococci. Related concepts include Mediastinitis and Sternotomy as the anatomical and surgical contexts for this condition.
Clinical presentation
Early signs include fever, chest pain, and drainage from the incision. The wound may appear red, swollen, or dehiscent, with tenderness over the sternum. In deep or mediastinal involvement, patients may develop tachycardia, leukocytosis, malaise, or hemodynamic instability. Some patients present with subtler signs, so a high index of suspicion is important in the first weeks after surgery, especially in high-risk individuals or those with prosthetic material.
Diagnosis
Diagnosis integrates clinical examination with laboratory and imaging studies. Cultures from wound drainage or tissue, blood cultures, and imaging help delineate the extent of infection. Computed tomography (Computed tomography) can identify mediastinal involvement or fluid collections. Diagnostic criteria used in practice emphasize both local wound findings and deeper infection extending into the mediastinum, aligning with standards for Surgical site infection and Mediastinitis.
Management
Management hinges on rapid source control and tailored antimicrobial therapy. Key elements include:
- Early surgical evaluation and prompt debridement or drainage when indicated, with thorough removal of infected tissue and, if necessary, prosthetic material or dead bone.
- Reconstruction of the chest wall or sternal defect when debridement creates substantial dead space, often using regional muscle flaps such as the Pectoralis major muscle to restore stability and vascular supply.
- Use of negative pressure wound therapy (Negative pressure wound therapy) after debridement to promote drainage and granulation, followed by definitive closure when feasible.
- Broad-spectrum initial antibiotics directed at likely pathogens (for example, coverage against Methicillin-resistant Staphylococcus aureus and gram-negative organisms) with subsequent tailoring to culture results, guided by an antibiotic stewardship approach. Typical regimens evolve as culture data become available and may transition to narrower-spectrum agents for a defined duration, commonly several weeks in cases of mediastinitis.
- Management of comorbid conditions that impair healing, such as diabetes, malnutrition, smoking, and obesity, to improve overall outcomes.
For context on antimicrobial choices and surgical techniques, see Antibiotic stewardship, Staphylococcus aureus, MRSA, Negative pressure wound therapy, and Pectoralis muscle flap.
Prevention and risk reduction
Prevention focuses on reducing infection risk before, during, and after surgery. Major components include:
- Preoperative risk assessment and optimization of chronic conditions (e.g., diabetes control, nutritional status).
- Perioperative antibiotic prophylaxis with appropriate agents and timing (for example, first-dose antibiotics given within the recommended window to cover skin flora).
- Skin preparation and sterile technique that minimize contamination, along with meticulous intraoperative handling of tissues and hardware.
- Postoperative care that supports healing: glucose control, avoidance of unnecessary chest-tube disruption, wound care protocols, and early detection of wound changes.
- Consideration of decolonization strategies for high-risk patients, such as nasal decolonization in certain settings, to reduce colonization by skin flora.
Controversies and debates
- Timing and extent of aggressive surgical intervention: Some clinicians favor rapid, extensive debridement with early muscle-flap reconstruction to prevent mediastinal spread, while others advocate a more staged approach in stable patients to minimize operative risk. The balance between decisive source control and preserving tissue can be nuanced.
- Use of negative pressure wound therapy: NPWT can reduce drainage and promote wound healing, but critics argue about cost-effectiveness and the strength of evidence in every clinical scenario. Proponents cite faster wound clearance and better preparation for closure in many patients.
- Reconstruction strategy: The choice between muscle flaps (e.g., pectoralis, latissimus dorsi) versus alternative methods hinges on defect size, patient anatomy, prior surgeries, and infection extent. Some centers advocate early flap coverage to improve vascular supply and prevent recurrent infection, while others opt for delayed reconstruction when infection is controlled.
- Antibiotic duration and stewardship: In mediastinitis, longer courses of antibiotics are common, but there is ongoing discussion about optimal duration to minimize resistance and adverse effects while ensuring eradication of infection. Stewardship aims to tailor duration to organism, infection extent, and patient response.
- Centralization vs local capability: High-volume, specialized centers tend to report better outcomes for complicated SWI, prompting policy debates about regionalization of care. Critics of regionalization warn about access barriers, while supporters argue that concentrated expertise improves survival and functional recovery.
- Policy framing and emphasis: Debates about healthcare policy sometimes frame surgical infection prevention within broader social or political narratives. A practical clinical perspective prioritizes timely, evidence-based care, patient autonomy, and cost-conscious decision-making, while acknowledging that real-world outcomes are shaped by both clinical quality and system-level factors. Critics who emphasize broader social determinants may argue for more expansive policies; from a pragmatic clinical viewpoint, improvements in SWI care most often come from ensuring high-quality surgical practice, rapid diagnosis, and efficient care pathways that reduce delays and complications.