Negative Pressure Wound Therapy for Patients With Complex Abdominal Wounds

The combination of open abdominal wounds and intra-abdominal infections is challenging to treat and often results in critical illness associated with high mortality. Objective. The aim of this study is to evaluate the feasibility of using negative pressure wound therapy (NPWT) to manage complex abdominal wounds and summarize relevant treatment experiences. Materials and Methods. A retrospective analysis of records from April 2012 to May 2015 identified 13 hospitalized patients with open abdominal wounds complicated by intra-abdominal infections. Patients received systemic antibiotics. Negative pressure wound therapy was applied at the bedside if prior debridement or decompression and drainage via laparotomy did not yield positive results or if the patient could not undergo surgery. Results. Of the 13 patients who were included in the study, 10 achieved wound closure (range, 19–52 days; median, 26 days). Among the 3 patients who did not achieve closure, 1 requested transfer to a hospital in his hometown, 1 developed an intestinal fistula that required surgery, and 1 died of a digestive tract hemorrhage unrelated to NPWT. Conclusions. By providing sufficient drainage, NPWT effectively removed wound fluid and infectious material. The reduced edema helped lower intra-abdominal pressure, reduce the risk of abdominal compartment syndrome and infection, and improve patient prognosis.

After years of development and improvement, negative pressure wound therapy (NPWT) has become a milestone in wound treatment. Contraindications for use in the treatment of acute and chronic wounds specify that NPWT should not be applied to an infected wound that has not been radically debrided, and foam dressings used with NPWT should not be placed in direct contact with exposed abdominal viscera, other organs, blood vessels, anastomotic sites, or nerves.¹

Open abdominal trauma leads to intra-abdominal infections in a cause-and-effect relationship. When treating patients with open abdominal wounds complicated by intra-abdominal infections, surgery does not always guarantee effective debridement and drainage. Repeated surgery also has some risks. If increased intra-abdominal pressure (IAP) is not identified and managed effectively in trauma patients, especially those with an abdominal injury, intra-abdominal hypertension can develop and rapidly deteriorate into abdominal compartment syndrome (ACS), which is quite difficult to handle and indicates a poor patient prognosis.^2,3

A retrospective record review was conducted to evaluate the use of NPWT to treat patients with abdominal wounds complicated with intra-abdominal infections.

Records from April 2012 to May 2015 were reviewed for all patients hospitalized with abdominal wounds complicated by intra-abdominal infections from Peking Union Medical College Hospital in Beijing, China. Patients were included if their open abdominal wounds had been treated with NPWT due to ineffective prior treatments or if patients were unable to tolerate further surgery. There was no limit placed on the age, sex, or wound causations and durations. Patients were excluded if their open abdominal wound resulted from tumors and/or contained exposed blood vessels or nerves. Patients with active abdominal bleeding or/and gastro-enteric fistula were also excluded. All patients received systemic antibiotics based on culture results (cilastatin/imipenem [Tienam; Merck & Co, Inc, Kenilworth, NJ] 500 mg intravenously (IV) every 8 hours; Ceftazidime [Fortum; GlaxoSmithKline UK, Brentford, Middlesex, UK] 2 g IV every 12 hours; or Cefoperazone Sodium and Sulbactam Sodium [Sulperazone; Haupt Pharma Latina S.R.L, Borgo San Michele LT, Italy] 3 g IV every 12 hours). Negative pressure wound therapy with reticulated open-cell foam dressings (V.A.C. Therapy with V.A.C. GranuFoam Dressings; KCI, an Acelity Company, San Antonio, TX) was applied at the bedside postoperatively. Daily patient data collected during NPWT included drainage volume, temperature, IAP, and peripheral blood procalcitonin (PCT) level. Dressings were changed every 72 hours.

Initially, NPWT was used in continuous mode (-75 mm Hg to -125 mm Hg) to facilitate drainage. When the infection had resolved and sufficient granulation tissue had formed in the wound bed to cover and close off access to the abdominal cavity, NPWT was switched to intermittent mode with the same negative pressure (-75 mm Hg to -125 mm Hg) to promote additional granulation tissue formation. After patient and wound conditions had improved (ie, wound bed was completely covered by healthy granulation tissue), surgical debridement was administered followed by wound closure using direct polymerizing or delayed sutures.

Twenty-one patients were found via the records, and 8 were excluded from this study. Thus, 13 patients (8 men and 5 women) with open abdominal wounds with intra-abdominal infections were included in the study. The overview of patient demographic and treatment details in eTable 1 indicate that most of the open abdominal wounds resulted from illness (cancer, pancreatitis, appendicitis) and trauma (traffic accidents, sharp instrument injuries).

Negative pressure wound therapy was applied for 3 to 45 days, ranging from -75 mm Hg to -125 mm Hg. With NPWT application, drainage volume markedly increased, reducing tissue edema. Intra-abdominal pressure also declined, mitigating ACS risk. Drainage volume, body temperature, IAP, and peripheral blood PCT were compared on the first day of NPWT and 72 hours after NPWT initiation (eTable 2). Intra-abdominal pressure levels were indirectly determined by the intravesical balloon catheter. Infections were addressed through positive treatment (systemic antibiotics and antishock life support), septic shock was easily resolved, and the wound was locally improved (ie, wound bed was completely covered by healthy granulation tissue). When patients underwent subsequent surgical debridement and wound repair, less debridement was necessary, less damage was caused, and surgical risks were decreased.

Ten of the 13 patients achieved wound closure. Of the 3 patients who did not achieve closure (eTable 1), case 1 developed an intestinal fistula that required surgery; case 2 requested transfer to a hospital in his hometown and received only 3 days of NPWT before the transfer, though his wound was healed by the first follow-up visit by the authors 3 months later; and case 3 died of a digestive tract hemorrhage unrelated to NPWT. 

Case 1 (Patient 12)
After a traffic accident, a 27-year-old man presented with multiple injuries including a small intestine rupture, a pelvic fracture, and an open fracture of the right lateral malleolus.  After exploratory laparotomy and repair of his ruptured jejunum were conducted in a local hospital, the patient suffered from expiratory dyspnea and was placed on mechanical ventilation and rushed to the intensive care unit (ICU). The patient was diagnosed with hyperpyrexia, IAP, and a ruptured wound. Drainage within the abdominal cavity consisted of turbid, purulent fluid, and the culture results indicated Enterobacter cloacae, Escherichia coli, and Leuconostoc lactis. Assuming the presence of septic shock, antishock therapy, anti-infective therapy, and other life support treatments were administered.

When the incision was opened at the bedside, exposed intestinal canals with contaminated surfaces swelled to the edges of the abdominal wall (Figure 1A). There were also numerous purulent hydrops in the abdominal cavity. With generalized intra-abdominal infection, poor drainage, and ACS, continuous NPWT at -125 mm Hg was administered (Figure 1B). Positive results were seen after 72 hours of continuous NPWT:  drainage volume significantly increased, body temperature significantly decreased, IAP slowly decreased, and septic shock resolved. 

With the patient’s vital signs stabilized, NPWT was switched to intermittent mode (0 mm Hg and -125 mm Hg) until granulation tissue was detected in the wound (Figure 1C). When the wound size decreased, reductions of the pelvic fracture and the right lateral malleolus fracture were carried out successfully.  After 20 total days of NPWT, surgical debridement and suturing of the abdominal wall wound were initiated; however, along with fresh granulation tissue, an intestinal canal with a fistulous orifice approximately 0.6 cm wide was discovered fully adhered to the peritoneum near the wound. Postoperative radiography showed a fistula connecting the jejunum with the abdominal wall. A large amount of effluent had drained out and damaged the tissue surrounding the fistula orifice. Enteral nutrition was supplied by placing a jejunal nutrient canal below the fistula orifice. After the fistula orifice was packed with petrolatum gauze for protection, continuous NPWT at -125 mm Hg was applied to the wound. Three weeks later, satisfactory granulation tissue had formed, and a stamp skin graft was applied to close the wound around the fistula orifice (Figure 1D). After 6 months of conservative treatment in the hospital (enteral nutrition by a nasojejunal feeding tube which was settled down the distal limb of the fistula, drainage of intestinal fluid and refeeding, adjusting electrolyte balance and blood glucose level), another intestinal fistula repair was conducted successfully. With the wound achieving full closure 7 months and 18 days after initial presentation, the patient recovered and was discharged.

Case 2 (Patient 3)
A 31-year-old woman, 8 months pregnant, suffered from abdominal pain for 7 days and dyspnea coupled with oliguria for 5 days after she gorged herself. Rushed to a local hospital, she was diagnosed with acute severe pancreatitis and intrauterine fetal death; in the emergency department, a caesarean section was performed to remove the deceased fetus. Postoperatively, the patient suffered from abdominal distension, dyspnea, and progressive oliguria. As plasmapheresis was not quite applicable to chylemia and hyperlipemia, she was immediately transferred to the ICU. The patient was diagnosed as having hyperpyrexia, respiratory failure, anuria, significantly increased abdominal pressure, and ascitic fluid. The patient also had an unhealed surgical incision with a large amount of yellow turbid exudate, and the culture results indicated Enterococcus faecium. After drainage by abdominocentesis and supportive care, including mechanical ventilation and plasma filtration, anti-infective therapy and enteral nutrition were administered; the patient’s general condition improved, but hyperpyrexia and abdominal distension persisted. With no evidence of intrauterine infection, her uterine involution was normal. When the patient coughed, however, abdominal pressure increased and ascitic fluid exuded. She also presented with generalized intra-abdominal infection, open abdominal wound infection (Figure 2A), and poor drainage. Continuous NPWT at -125 mm Hg was applied at the bedside. With increased drainage by NPWT, the patient’s body temperature lowered and granulation tissue formed in the wound bed (Figure 2B). The absence of ascitic fluid exudation after the patient coughed indicated the abdominal cavity was no longer connected to the wound. Then, NPWT at the same pressure was applied in intermittent mode. During a total of 45 days of NPWT, granulation tissue grew rapidly and wound size decreased significantly (Figure 2C). At that point, surgical debridement and suturing were performed under local anesthesia, and the wound progressed to achieve full wound closure 55 days post initial presentation (Figure 2D). 

An open infected abdominal wound, a common clinical problem, becomes difficult to treat when it is complicated by simultaneous intra-abdominal infection. Treatment of these challenging patients typically involves surgery or interventional drainage of ascitic fluid with multiple dressing changes to provide sufficient drainage of infectious peritoneal fluid. While this approach may yield poor results, exploratory or interventional surgery poses a greater risk due to the generalized intraabdominal infection and increased ascites. The development of septicemia and septic shock further complicates patient management. When IAP increases and ACS occurs, the intestines swell to the edge of the abdominal wall, resulting in an extremely poor prognosis. Negative pressure wound therapy reduces tissue edema, promotes granulation tissue growth, improves local blood flow, and reduces wound size.⁴ When applied for treating an open abdominal wound complicated by intra-abdominal infection, NPWT also ensures sufficient drainage and removes exudate and infectious materials.

As demonstrated in this retrospective study, there were significant changes in body temperature and drainage volume after NPWT was administered (eTable 2). These could be deemed as proof of effectiveness based on the authors’ experience and positively correlated with patient prognosis. Currently, PCT is believed to be highly specific for bacterial infections and, in particular, systemic bacterial infections. Because PCT levels go up in the early stages of peritonitis, septicemia, sepsis, and septic shock, changes in peripheral blood PCT levels are of some value in differential and early diagnosis of intra-abdominal infections.⁵ The change of PCT level in positive correlation with systemic infections can also be used in the assessment of curative effects and prognostic judgment.^6,7 With fewer influencing factors as well as high sensitivity and specificity, PCT level has a greater value in the diagnosis of bacterial infections than white blood cell count, C-reactive protein, etc.⁸ Conversely, decreased PCT levels after NPWT may indicate reduction of infectious materials. If IAP, another indicator influencing patient prognosis,⁹ increases, ACS occurs (followed by anuria as well as respiratory and circulatory disorders), resulting in a poor prognosis indeed.¹⁰ Presently, an effective way to treat ACS is a decompressive laparotomy; however, this gives rise to an overly large, difficult-to-close incision, bulging abdominal contents, intestinal fistulas, and hemodynamic disturbance.¹¹ In contrast, use of NPWT in the present study ensured effective drainage and alleviated tissue edema. As IAP lowered, the risk of ACS decreased and patient prognosis improved. 

To prevent possible damage, negative pressure foam dressings must not be placed in direct contact with the viscera or other exposed organs or structures. The authors normally use porous hydrocolloid dressings (Physiotulle Ag; Coloplast Ltd, Lynch Wood, Peterborough, UK) to cover the intestines, because these dressings contain silver ions that fight off bacteria. A nonclinical porcine study¹² reported that 8 layers of paraffin gauze (Jelonet; Smith & Nephew, London, UK) placed under an NPWT foam dressing (ABThera fenestrated visceral protective layer; KCI, an Acelity Company, San Antonio, TX) significantly reduced negative pressure at the bowel at -125 mm Hg but not at lower negative pressure levels. The median pressure reduction through the 8 layers of gauze was 13%.¹² Even so, exposure of intestinal canals to NPWT over a long period of time may still result in development of an intestinal fistula (as shown in case 1), even when granulation tissue provides total coverage. Therefore, timely abdominal closure as well as decompression and suturing to reduce wound size are both effective ways to prevent intestinal fistulas.

The many options for temporary abdominal closure (TAC) currently include therapies such as a Bogotá bag, Wittmann Patch (Starsurgical, Burlington, WI), Barker’s vacuum pack, reticulated open-cell foam dressings, and ABThera Open Abdomen Negative Pressure Therapy System (KCI, an Acelity Company, San Antonio, TX).¹³ A systematic review by Roberts et al¹⁴ included 2 randomized controlled trials,^15,16 3 prospective cohort studies,^17-19 and 6 retrospective cohort studies.^20-25 The authors¹⁴ reported that while further prospective studies would be needed to reach a definitive conclusion, limited data suggest the use of NPWT, when compared with other TAC methods might be associated with improved outcomes in patients with an open abdomen (especially those in critical condition due to sepsis).

When other proactive abdominal closure techniques, such as a dynamic closure procedure or skin graft in grade 4 open abdomens, were combined with NPWT, the closure rate significantly increased.²⁶ A small, randomized controlled trial²⁷ compared the combination of NPWT and a consistent tension system (ABRA Abdominal Wall Closure System; Canica Design,  Almonte, Ontario, Canada) (NPWT/tension system; n = 8) to NPWT alone (n = 6) for the treatment of patients with an open abdomen. There were no significant differences in the primary closure rates between the groups; however, the NPWT/closure system group had significantly fewer (1 vs. 3; P < .01) and shorter (58 vs. 212 minutes; P < .01) operations.²⁷

As the current retrospective study is limited by a small size (13 patients) and lacks a comparison group, more case studies with long-term outcomes and comparison of other abdomen closure techniques are needed. The results indicate NPWT can be regarded as an easy, convenient, and effective way to treat open abdominal wounds complicated by intra-abdominal infections. Outcomes will be more favorable the earlier NPWT is administered for those types of patients.

In this retrospective study, NPWT’s removal of fluid and infectious materials from open abdominal wounds associated with intraabdominal infections helped lower IAP and reduce the risk of ACS. Using NPWT to promote granulation tissue formation also helped with wound closure. In the authors’ experience, using NPWT to treat these critically ill patients saved time, created opportunities for follow-up treatment, reduced risks in additional surgeries, and significantly improved patient prognosis. 

Affiliation: Plastic & Aesthetic Surgery Center, Peking Union Medical College Hospital, Beijing, China

Correspondence:
Xiaojun Wang, MD
Plastic & Aesthetic Surgery Center
Peking Union Medical College Hospital
Peking Union Medical College and Chinese Academy of Medical Sciences
No. 1 Shuaifuyuan
Dongcheng District
Beijing 100730, China
xjwang100@hotmail.com

Disclosure: The authors disclose no financial or other conflicts of interest.