NPWT for Third Spacing: Not a Standard Indication
Negative pressure wound therapy (NPWT) is not indicated for managing third spacing itself, but rather for managing the open abdomen wounds that result from conditions causing third spacing, such as abdominal compartment syndrome (ACS). The primary role of NPWT in this context is to provide temporary abdominal closure, actively drain fluid, prevent loss of abdominal domain, and facilitate delayed fascial closure 1.
Understanding the Clinical Context
Third spacing refers to fluid accumulation in interstitial spaces, commonly occurring in critically ill patients with conditions like sepsis, trauma, or post-operative states. When third spacing leads to abdominal compartment syndrome requiring decompressive laparotomy, NPWT becomes the treatment of choice for the resulting open abdomen—not for the third spacing per se 1.
Primary Indications for NPWT in Open Abdomen
Grade 1 and 2 Open Abdomen (Early Stages)
NPWT should be used as first-line therapy in Grade 1 and 2 open abdomen where delayed primary closure is planned, including following decompression of ACS 1. The evidence supporting this is compelling:
NPWT significantly normalizes serum lactates and systemic inflammatory mediators compared with passive drainage methods like Bogota Bag, indicating it can influence patient physiological stability in the immediate post-laparotomy period 1
NPWT helps prevent loss of abdominal domain while providing active fluid drainage, which is critical when managing patients with ongoing third spacing and fluid shifts 1
NPWT is a suture-less technology that does not damage fascial tissue, unlike mesh-based techniques, preserving tissue integrity for eventual closure 1
Active Fluid Management Benefits
The mechanism by which NPWT addresses fluid accumulation includes:
NPWT removes wound exudates and inflammatory fluids, reducing edema in the wound bed 2
NPWT increases local blood flow and tissue perfusion, which enhances the body's ability to reabsorb third-spaced fluid 2
The interface serves as an enhanced drainage system for fluid that may otherwise be retained in the deep abdominal cavity 1
Sequential Dynamic Closure Technique
Application of sequential dynamic closure technique along with NPWT should be considered to counteract fascial retraction and facilitate delayed primary closure 1. This approach:
Results in an overall fascial closure rate of 79%, the highest of any closure technique when NPWT is combined with dynamic closure methods 1
Allows for staged approximation of the fascia at each repeat laparotomy, preventing tension-free closure that avoids ischemia and recurrent ACS 1
Can extend the window for fascial closure up to 21 days or longer, allowing adequate time for resolution of third spacing and patient stabilization 1
Critical Prerequisites and Contraindications
Before applying NPWT in any infected or contaminated wound:
Complete surgical debridement of all necrotic and infected tissue must be performed first, continuing into healthy-looking tissue 2
NPWT should never be applied to wounds with residual necrotic tissue or uncontrolled infection 2
Always use a non-adherent interface layer to protect exposed organs and prevent progression to more complicated wound grades 1
Practical Application Parameters
When using NPWT for open abdomen management:
Standard pressure settings of 75-125 mmHg can be used, with lower pressures (75-80 mmHg) appropriate for vulnerable anatomic areas 3
Dressing changes should occur every 2-3 days, which is standard for NPWT applications 3
Patients closed at the first repeat laparotomy are more likely to have been managed with NPWT (73% vs 49%, p<0.001), and NPWT is an independent predictor for early closure 1
Post-Closure Management
Once fascial and skin closure is achieved, application of incisional NPWT on the closed incision should be considered to facilitate healing 1. This approach:
Significantly reduces wound complications including wound dehiscence compared with standard gauze dressings 1
Provides a "splinting effect" that aids patient mobility by supporting the wound, which is important for reducing ICU stay duration 1
Reduces overall wound complications and infection rates in high-risk abdominal incisions 1
Common Pitfall to Avoid
The most critical error is conceptualizing NPWT as a treatment for third spacing itself. NPWT does not directly treat third spacing—it manages the open abdomen that results from surgical decompression of conditions complicated by third spacing 1. The fluid drainage provided by NPWT is beneficial, but the primary goals are maintaining abdominal domain, protecting viscera, and facilitating eventual fascial closure once the patient's fluid status and physiology have stabilized.