Overview
Definition:
Vacuum-assisted closure (VAC), also known as negative pressure wound therapy (NPWT), is a technique that applies subatmospheric pressure to a wound bed using a sealed dressing and a vacuum pump
In the context of enterocutaneous fistulas (ECF), VAC therapy aims to manage the efflument, promote granulation tissue formation, reduce edema, and prepare the wound for definitive closure or reconstruction.
Epidemiology:
Enterocutaneous fistulas are a serious complication, occurring in 1-2% of all abdominal surgeries, with higher rates following reoperations or in patients with inflammatory bowel disease
Mortality can range from 5-15%, significantly increased with high-output fistulas and malnutrition.
Clinical Significance:
ECFs represent a significant challenge in surgical practice due to their high morbidity, prolonged hospital stays, and substantial healthcare costs
Effective management is crucial for patient recovery, prevention of sepsis, nutritional support, and wound healing
VAC therapy has emerged as a valuable adjunct in managing these complex wounds.
Indications
General Indications:
VAC therapy is indicated for ECFs when conservative management fails or is not feasible
Key considerations include the fistula output, the surrounding skin condition, and the presence of infection
It can be used in both low- and high-output fistulas, as well as those with surrounding cellulitis or desiccation.
Specific Indications For Ecf:
High fistula output requiring containment and management
Presence of surrounding infected or unhealthy tissue
Desire to reduce wound edema and promote granulation
Preparation of the wound bed for surgical closure or ostomy creation
Patients with malnutrition or compromised healing potential
Bridging therapy while systemic conditions are addressed.
Contraindications:
Absolute contraindications include untreated osteomyelitis, exposed blood vessels or organs within the wound, necrotic tissue with eschar, and active malignancy within the wound
Relative contraindications include active bleeding, fragile tissues, and fistulas with insufficient surrounding healthy tissue for seal.
Preoperative Preparation
Patient Assessment:
Thorough assessment of the patient's nutritional status, fluid and electrolyte balance, and overall physiological stability
Evaluation of comorbidities such as diabetes, immunosuppression, and peripheral vascular disease.
Wound Assessment:
Detailed characterization of the fistula, including its location, size, output, and presence of surrounding skin breakdown or infection
Cultures should be obtained if infection is suspected
Imaging studies may be needed to delineate the fistula tract.
Nutritional Support:
Aggressive nutritional optimization is paramount
This often involves parenteral or enteral nutrition to meet increased metabolic demands and promote healing
Consultation with a nutritionist is recommended.
Antibiotic Therapy:
Broad-spectrum antibiotics should be initiated if signs of infection or sepsis are present
Cultures guide further antibiotic selection
Prophylactic antibiotics may be considered based on individual risk factors.
Procedure Steps
Wound Preparation:
The fistula efflument is managed with appropriate stoma appliances or collection systems
The surrounding healthy skin is protected with a skin barrier
Any non-viable tissue is debrided.
Foam Placement:
A specialized open-cell foam dressing is cut to fit the wound bed, ensuring it fills the fistula tract without protruding
The foam should not extend beyond the wound margins onto healthy skin.
Seal Application:
A transparent adhesive film dressing is applied over the foam, creating an airtight seal
This film extends onto the healthy periwound skin, ensuring no air leaks
The film is trimmed to create a flap for connecting the tubing.
Tubing Connection:
A suction port or tube is placed into the foam dressing through the film seal
The tube is connected to a VAC unit, which is set to deliver continuous or intermittent negative pressure, typically between 75-125 mmHg.
Dressing Changes:
Dressing changes are typically performed every 48-72 hours or as needed, depending on the wound output and the integrity of the seal
During changes, the wound is assessed, debrided if necessary, and a new foam and seal are applied.
Postoperative Care
Monitoring Vacuum Unit:
Continuous monitoring of the VAC unit to ensure optimal pressure delivery and to detect any leaks or alarms
Fluid output from the canister should be recorded and analyzed.
Wound Monitoring:
Regular assessment of the wound bed for signs of granulation tissue formation, reduction in edema, and decrease in exudate
Any signs of infection or complications must be promptly identified.
Nutritional Management:
Continued aggressive nutritional support is essential throughout the VAC therapy period and beyond.
Pain Management:
Adequate analgesia is crucial, as the negative pressure can cause discomfort
Pain medication should be administered before dressing changes and regularly monitored.
Complications
Early Complications:
Skin maceration or breakdown due to poor seal or prolonged contact with exudate
Pain and discomfort
Bleeding from fragile wound edges
Infection propagation.
Late Complications:
Delayed healing if VAC therapy is not optimized
Granulation tissue hypertrophy
Contracture of the surrounding skin if not managed carefully
Recurrence of fistula if underlying cause is not addressed.
Prevention Strategies:
Ensuring an airtight seal
Regular monitoring of the VAC unit and dressing
Timely dressing changes
Adequate pain management
Aggressive wound debridement
Optimizing nutritional status
Appropriate management of associated comorbidities.
Prognosis
Factors Affecting Prognosis:
Fistula output volume
Nutritional status of the patient
Presence and control of sepsis
Underlying etiology of the fistula (e.g., malignancy, radiation)
The skill of the surgical team in managing the VAC device and the wound
The extent of surrounding healthy tissue for seal.
Outcomes:
VAC therapy can significantly improve outcomes for patients with ECFs by facilitating wound healing, reducing complications, and decreasing hospital stay
It often acts as a bridge to definitive surgical management or allows for spontaneous closure in selected cases.
Follow Up:
Close follow-up is required after VAC therapy is discontinued
This includes monitoring for wound healing, recurrence of fistula, and long-term nutritional support
Depending on the etiology, further investigations or treatments may be necessary.
Key Points
Exam Focus:
VAC therapy is an adjunct for ECF management, not a standalone cure
Focus on indications, contraindications, and principles of application
Understanding how it mechanically promotes healing: edema reduction, granulation tissue promotion, fluid removal, and maintaining moist wound environment.
Clinical Pearls:
Ensure adequate sealing is paramount
Protect the periwound skin meticulously
Document output diligently
A multidisciplinary approach involving surgeons, nurses, and nutritionists is key
VAC therapy is most effective when combined with addressing the underlying cause of the fistula.
Common Mistakes:
Failure to achieve an airtight seal leading to inadequate negative pressure
Incomplete debridement of necrotic tissue
Inadequate nutritional support
Neglecting periwound skin protection
Using inappropriate foam or seal
Incorrect pressure settings.