Overview
Definition:
Open abdomen refers to a surgical management strategy where the abdominal wall is deliberately left open after laparotomy, usually due to the inability to close it safely
Negative Pressure Therapy (NPT), often referred to as Vacuum-Assisted Closure (VAC) therapy, is a technique used to manage open abdomens by applying controlled negative pressure to the wound, promoting wound healing and facilitating eventual closure.
Epidemiology:
The incidence of open abdomens varies widely depending on the underlying pathology, ranging from 1-5% in elective general surgery to over 10-20% in severe trauma, emergency laparotomies for sepsis, and for abdominal compartment syndrome
NPT has become a cornerstone in managing these complex cases, with widespread adoption in surgical centers.
Clinical Significance:
Open abdomen management is critical in preventing and treating severe abdominal complications such as abdominal compartment syndrome, intra-abdominal hypertension, and large incisional hernias
NPWT aids in fluid management, reduces bacterial load, promotes granulation tissue formation, and facilitates staged abdominal reconstruction, significantly improving outcomes in critically ill patients and reducing morbidity.
Indications
Indications For Open Abdomen:
Situations where primary fascial closure is not feasible or safe
This includes severe abdominal trauma with significant contamination or edema
Intra-abdominal sepsis with diffuse peritonitis and bowel distension
Abdominal compartment syndrome (ACS) requiring temporary decompressive laparotomy
Massive retroperitoneal hemorrhage
Planned staged abdominal reconstruction after multiple re-explorations
Bowel decompression for severe ileus.
Indications For Npt:
Application of NPT is indicated for managing open abdomens to control wound complications
Specific indications include: promoting wound granulation for eventual closure
Managing large, complex abdominal wall defects
Reducing edema and promoting fluid evacuation
Sequestering and draining contaminated wound fluid
Facilitating temporary abdominal closure when primary closure is impossible
Preventing entero-atmospheric fistulas.
Contraindications For Npt:
Absolute contraindications are rare but include untreated coagulopathy, active untreated sepsis if not managed concomitantly, and unresectable malignancy involving the wound
Relative contraindications may include untreated fistulas without adequate drainage, exposed vital organs (e.g., spinal cord, major vessels) without proper interface, and if the patient cannot tolerate the negative pressure due to hemodynamic instability.
Preoperative Preparation
Patient Assessment:
Thorough assessment of hemodynamic stability, coagulation profile, nutritional status, and severity of illness is crucial
Evaluation of the extent of contamination and bowel viability guides subsequent management
Aggressive fluid resuscitation and correction of coagulopathy are paramount.
Surgical Planning:
Decision for open abdomen is made intraoperatively
If NPT is planned, appropriate dressing kits and negative pressure machine are prepared
Careful consideration of the abdominal wall closure strategy is needed, including timing of delayed primary closure or definitive reconstruction.
Anesthesia Considerations:
Anesthetic management focuses on maintaining hemodynamic stability, adequate oxygenation, and ventilation
Monitoring of intra-abdominal pressure is essential
Neuromuscular blockade may be required for abdominal wall relaxation
Pain management is critical.
Procedure Steps Npt
Wound Preparation:
Thorough irrigation of the abdominal cavity to remove gross contamination
Debridement of non-viable tissue
If bowel is exteriorized, it should be covered with sterile, moist saline-soaked dressings
The exposed peritoneum should be protected.
Dressing Application:
A specialized foam dressing or gauze is cut to fit the defect, ensuring it covers the entire exposed surface of the abdomen
Care is taken to avoid placing dressings directly over major vessels or solid organs without appropriate interface material.
Seal And Connection:
An adhesive drape is applied over the foam/gauze to create a seal
A connecting tube is inserted through the drape into the foam/gauze, and connected to the NPWT device
The device is set to a prescribed negative pressure setting, typically between 75-125 mmHg, often in a continuous or intermittent mode.
Monitoring And Adjustment:
Regular monitoring of wound status, fluid output, and patient hemodynamics is essential
The dressing and foam should be changed every 24-72 hours or as needed based on wound drainage and contamination levels
The negative pressure setting may be adjusted based on patient tolerance and wound response.
Postoperative Care
Monitoring:
Continuous monitoring of vital signs, fluid balance (intake and output), laboratory parameters (hemoglobin, electrolytes, renal function), and abdominal distension
Assessment for signs of worsening sepsis or organ dysfunction
Close monitoring of NPWT system function and wound characteristics.
Nutritional Support:
Early enteral nutrition is preferred to maintain gut integrity and function
Parenteral nutrition may be required if enteral feeding is not feasible
Adequate protein and caloric intake are crucial for wound healing and recovery.
Fluid Management:
Aggressive fluid management is critical to maintain euvolemia and optimize organ perfusion
Electrolyte balance must be strictly maintained
Management of third-space fluid losses is a key challenge.
Pain Management:
Adequate pain control is essential, utilizing multimodal approaches including patient-controlled analgesia (PCA) if appropriate
Opioids, NSAIDs, and adjuncts like gabapentin may be used
Consideration of regional anesthesia techniques if feasible.
Complications
Early Complications:
Worsening sepsis or organ failure
Intra-abdominal hypertension or ACS if negative pressure is insufficient or bowel distension recurs
Bleeding from the wound site
Skin maceration or breakdown due to prolonged contact with exudate or adhesive drapes
Entero-atmospheric fistula formation
Herniation of abdominal contents through the defect.
Late Complications:
Incisional hernia formation is a significant long-term complication
Chronic enterocutaneous fistulas
Adhesions leading to bowel obstruction
Abdominal wall deformities
Impaired respiratory mechanics due to reduced abdominal compliance
Poor cosmetic outcome.
Prevention Strategies:
Judicious selection of patients for open abdomen
Prompt and adequate resuscitation
Effective control of sepsis
Appropriate NPWT application and timely dressing changes
Gradual restoration of abdominal wall integrity
Early mobilization and rehabilitation
Proactive management of nutritional needs.
Key Points
Exam Focus:
Understand the indications and contraindications for open abdomen and NPWT
Key aspects include dressing application technique, negative pressure settings, and monitoring parameters
Be familiar with common complications like ACS and incisional hernias
DNB/NEET SS often tests management algorithms in trauma and sepsis.
Clinical Pearls:
Always protect vital structures from direct foam contact with a barrier
Ensure a good seal to maintain negative pressure
Monitor fluid output diligently as it reflects systemic fluid status and wound condition
Consider NPWT for abdominal wall closure even in elective cases with high risk of dehiscence.
Common Mistakes:
Inadequate fluid resuscitation or correction of coagulopathy prior to NPWT
Failure to adequately debride non-viable tissue
Poor sealing leading to ineffective negative pressure
Applying excessive negative pressure leading to pain or tissue damage
Delaying definitive abdominal wall closure or reconstruction.