Overview
Definition:
Flap coverage for infected sternotomy refers to the surgical reconstruction of the sternal wound following sternotomy, when infection has led to dehiscence, osteomyelitis, or mediastinitis
It involves using vascularized tissue (flaps) to cover the exposed sternal bone and surrounding infected tissues, promoting healing and preventing further complications.
Epidemiology:
Deep sternal wound infection (DSWI) occurs in 0.4% to 5% of patients undergoing median sternotomy, particularly after cardiac surgery
Risk factors include diabetes, obesity, prolonged ventilation, re-operation, and immunosuppression
Flap coverage is indicated in a significant subset of these patients.
Clinical Significance:
Infected sternotomy poses a life-threatening complication, leading to sepsis, mediastinitis, and increased mortality
Effective flap coverage is crucial for wound closure, eradication of infection, restoration of chest wall integrity, and enabling early mobilization, significantly impacting patient outcomes and recovery.
Clinical Presentation
Symptoms:
Fever and chills
Increased sternal wound pain and tenderness
Purulent discharge from the wound
Chest wall instability or paradoxical chest wall movement
Shortness of breath or dyspnea
Sepsis symptoms including hypotension and tachycardia.
Signs:
Edematous and erythematous sternal wound with purulent drainage
Palpable instability of the sternum
Crepitus over the sternal region
Signs of systemic sepsis: fever, tachycardia, hypotension
Mediastinal widening on imaging.
Diagnostic Criteria:
Clinical diagnosis based on signs and symptoms of infection
Confirmed by wound culture, imaging (CT scan showing osteomyelitis, fluid collections, or mediastinitis), and laboratory markers of inflammation (elevated CRP, WBC count).
Diagnostic Approach
History Taking:
Detailed history of cardiac surgery, duration of sternal wires, previous wound complications, comorbidities (diabetes, immunosuppression, peripheral vascular disease), antibiotic use, and onset of symptoms
Any recent instrumentation or foreign body insertion.
Physical Examination:
Systematic examination of the sternal wound for erythema, edema, warmth, tenderness, and drainage
Assessment of chest wall stability
Palpation for crepitus
Full cardiopulmonary examination to assess for signs of mediastinitis or sepsis.
Investigations:
Complete Blood Count (CBC) with differential: Elevated WBC count
C-reactive protein (CRP): Elevated
Blood cultures: To identify causative organisms
Wound culture and sensitivity: Essential for guiding antibiotic therapy
Chest X-ray: May show mediastinal widening or pleural effusion
CT scan of the chest: Gold standard for assessing sternal osteomyelitis, mediastinal abscesses, and surrounding tissue involvement
Echocardiogram: To rule out endocarditis if suspicion is high.
Differential Diagnosis:
Superficial sternal wound infection
Post-operative seroma or hematoma
Musculoskeletal chest wall pain
Pneumonia
Acute myocardial infarction
Lung contusion.
Management
Initial Management:
Prompt surgical debridement of all necrotic, infected, and devitalized tissue
Aggressive antibiotic therapy guided by Gram stain and culture sensitivities
Hemodynamic stabilization if sepsis is present
Nutritional support.
Medical Management:
Intravenous antibiotics should be initiated empirically and then tailored based on culture results
Broad-spectrum coverage initially, targeting common pathogens like Staphylococcus aureus (including MRSA) and Gram-negative bacilli
Common regimens include Vancomycin or Linezolid plus a broad-spectrum Gram-negative agent (e.g., Piperacillin-Tazobactam, Meropenem)
Duration typically 4-6 weeks, often with a switch to oral therapy for consolidation.
Surgical Management:
Surgical debridement and reconstruction
Primary goal is to remove all infected bone and soft tissue
Flap coverage is essential for definitive closure
Common flap options include: Pectoralis major myocutaneous flaps (bilateral or single), Rectus abdominis myocutaneous flaps, Latissimus dorsi myocutaneous flaps
These flaps provide well-vascularized tissue to fill dead space, deliver antibiotics to the wound bed, and promote granulation and epithelialization
Vacuum-assisted closure (VAC) therapy may be used as an adjunct before or after flap coverage.
Supportive Care:
Intensive care unit (ICU) monitoring for hemodynamics and respiratory status
Nutritional support (parenteral or enteral nutrition) is crucial due to catabolic state
Pain management
Wound care, including regular dressing changes and monitoring for flap viability
Physiotherapy and early mobilization to prevent pulmonary complications and DVT.
Complications
Early Complications:
Flap necrosis or partial loss
Wound dehiscence
Persistent infection
Sepsis
Pleural effusion or empyema
Pneumonia
Deep vein thrombosis (DVT) or pulmonary embolism (PE).
Late Complications:
Chronic sternal instability
Chest wall deformity
Chronic pain
Recurrent infection
Fistula formation
Impaired respiratory function.
Prevention Strategies:
Meticulous surgical technique during sternotomy
Strict aseptic precautions
Judicious use of sternal wires
Prompt recognition and management of superficial wound infections
Early operative intervention for signs of DSWI
Appropriate antibiotic prophylaxis.
Prognosis
Factors Affecting Prognosis:
The extent of infection and tissue loss
Patient comorbidities and nutritional status
The success of surgical debridement and flap viability
Promptness of diagnosis and treatment
Development of sepsis or multi-organ failure.
Outcomes:
With timely and comprehensive management including appropriate flap coverage, the prognosis can be good, with successful wound healing and return to function
However, mortality rates for DSWI remain significant, ranging from 10% to over 30% in severe cases
Long-term morbidity is also common.
Follow Up:
Close follow-up is essential to monitor flap viability, wound healing, and signs of recurrent infection
This includes regular clinical examinations and wound assessments
Patients may require long-term pain management and physiotherapy
Imaging studies may be repeated if recurrence is suspected.
Key Points
Exam Focus:
DNB/NEET SS exams often test the management algorithm for deep sternal wound infections, including indications for flap coverage and common flap choices
Understanding the risk factors and diagnostic hallmarks is critical.
Clinical Pearls:
Aggressive debridement is paramount
Never underestimate a sternal wound infection
early surgical intervention is key
When choosing a flap, consider the defect size, location, and patient comorbidities
Vascularized tissue is essential for filling dead space and combating infection.
Common Mistakes:
Delaying surgical intervention
Inadequate debridement of infected bone
Relying solely on antibiotics without surgical source control
Failure to consider the vascular supply of flap tissue
Insufficient postoperative monitoring of flap viability.