Pressure at the Bowel Surface during Topical Negative Pressure Therapy of the Open Abdomen: An Experimental Study in a Porcine Model

Optimal tentative abdominal closure for open abdomen: a multicenter retrospective observational study (OPTITAC study)

BACKGROUND

Primary fascia closure is often difficult following an open abdomen (OA). While negative-pressure wound therapy (NPWT) is recommended to enhance successful primary fascia closure, the optimal methods and degree of negative pressure remain unclear. This study aimed to elucidate optimal methods of NPWT as a tentative abdominal closure for OA to achieve primary abdominal fascia closure.

MATERIALS AND METHODS

A multicenter, retrospective, cohort study of adults who survived OA greater than 48 h was conducted in 12 institutions between 2010 and 2022. The achievement of primary fascia closure and incidence of enteroatmospheric fistula were examined based on methods (homemade, superficial NPWT kit, or open-abdomen kit) or degrees of negative pressure (<50, 50-100, or >100 mmHg). A generalized estimating equation was used to adjust for age, BMI, comorbidities, etiology for laparotomy requiring OA, vital signs, transfusion, severity of critical illness, and institutional characteristics.

RESULTS

Of the 279 included patients, 252 achieved primary fascia closure. A higher degree of negative pressure (>100 mmHg) was associated with fewer primary fascia closures than less than 50 mmHg [OR, 0.18 (95% CI: 0.50-0.69), P =0.012] and with more frequent enteroatmospheric fistula [OR, 13.83 (95% CI: 2.30-82.93)]. The methods of NPWT were not associated with successful primary fascia closure. However, the use of the open-abdomen kit was related to a lower incidence of enteroatmospheric fistula [OR, 0.02 (95% CI: 0.00-0.50)].

CONCLUSION

High negative pressure (>100 mmHg) should be avoided in NPWT during tentative abdominal closure for OA.

Negative-Pressure Wound Therapy: What We Know and What We Need to Know

Negative-pressure wound therapy (NPWT) promotes wound healing by applying negative pressure to the wound surface. A quarter of a century after its introduction, NPWT has been used in various clinical conditions, although molecular biological evidence is insufficient due to delay in basic research. Here, we have summarized the history of NPWT, its mechanism of action, what is currently known about it, and what is expected to be known in the future. Particularly, attention has shifted from the four main mechanisms of NPWT to the accompanying secondary effects, such as effects on various cells, bacteria, and surgical wounds. This chapter will help the reader to understand the current status and shortcomings of NPWT-related research, which could aid in the development of basic research and, eventually, clinical use with stronger scientific evidence.

Abdominal compartment syndrome in burns patients: Introduction of an evidence-based management guideline and algorithm

ABSTRACT

Abdominal compartment syndrome is a serious potential complication of burn injury, and carries high morbidity and mortality. Although there are generalised published guidelines on managing the condition, to date no management algorithm has yet been published tailored specifically to the burn injury patient. We set out to examine the literature on the subject in order to produce an evidence based management guideline, with the aim of improving outcomes for these patients. The guideline covers early detection and assessment of the condition as well as optimum medical, surgical and postoperative management. We believe that this guideline provides a much needed benchmark for managing burns patients with raised intra-abdominal pressure, as well as providing a template for further research and improvements in care.

The Effect of Negative Pressure in the Abdominal Cavity With Suprasorb CNP on Abdominal Organs-An Experimental Study

Since the introduction of negative pressure therapy of the abdomen, care has been taken to protect the intestine from the effects of negative pressure in order to avoid impairments of abdominal organs. As an alternative to the widespread AB-Thera^R system (KCI, San Antonio, Texas, USA), the different concept of Suprasorb CNP^R (Lohmann & Rauscher, Austria-Germany) was introduced by the producer with the premise of achieving a better therapeutic effect. Due to numerous pores of the film, the effects of the negative pressure are brought to the surface of the intestinal organs and these effects were tested on seven experimental animals. Particular attention was paid to the small intestine, colon, liver, and pancreas. Over 8 h continuously, three animals were tested with −80 mmHg, 4 with −60 mmHg. The results showed no macroscopic pathological changes. The histological results showed borderline changes in the small intestine and colon with −80 mmHg application, minimal or none with −60 mmHg. The liver and pancreas were found free of pathological changes. For use on human organs, the intra-abdominal application of −60 mmHg for the Suprasorb CNP system is proposed as the standard.

Effect of Negative Pressure Therapy on Open Abdomen Treatments. Prospective Randomized Study With Two Commercial Negative Pressure Systems

Introduction: The use of negative pressure dressings for open abdominal therapy has made a great impact on strategies for open abdominal treatment. Observed intestinal damage and developement of fistula formation raises questions about safety of commonly used systems (AB-Thera). The most common used system uses foils for shielding intestines directly from negative pressure. As an alternative a system with open pore dressing in double layer film was introduced (Suprasorb CNP) and proved to safe in animal studies. We compared the effects of this two systems on patients requiring open abdominal treatment. Materials and methods: Patients with secondary peritonitis in at least two abdominal quadrants were included in this randomized study. Inclusion criteria were secondary peritonitis (ACS), abdominal compartment syndrome, and abdominal trauma combined with ACS and/or contaminated abdomen. Patients with active bleeding and pancreatitis were not included. We examined Mannheim peritonitis Index (MPI), bloodcount, PCT, amount of fluid collected, and morphological changes on the bowel. Data were collected on day 2, 4, 7, 14, 21, and 28. Primary end point was fascial closure. Examination was terminated in case of death and damage to the abdominal organs. Groups were compared using Mann Whitney U-test and chi square test. Trend evaluation was evaluated using an one way repeated measure analysis of variance. P-values below 0.05 was considered significat. Results: Thirty four patients were included between August 2010 and September 2012. There were no significant difference between two groups in MPI, age, and gender. Mean duration of treatment, WBC, CRP, and abdominal closure rate were not significantly different between groups. Suprasorb CNP System collected twice more fluid than AB-Thera and decreased PCT on significantly faster rate than AB-Thera. Four patients died (11%) and four patients developed enteric fistula (11%). Closure rate was achieved in 27 out of 34 Patients (79.5%). Closure rate was not significantly different between groups. Conclusion: The use of both systems proved to be efficient and safe. The application of well-dosed, moderate negative pressure on contaminated areas of the abdomen seems to have a lot of potential and it is worth directing greater research potential in this direction.

Delayed Closure of Open Abdomen in Septic Patients Treated With Negative Pressure Vacuum Therapy and Dynamic Sutures: A 10-Years Follow-Up on Long-Term Complications

Introduction: Patients with open abdomen after surgical interventions associated with the complication of secondary peritonitis are successfully treated with negative pressure wound therapy. The use of dynamic fascial sutures reduces fascial lateralization and increases successful delayed fascial closure after open abdomen treatment.

Methods: In 2017 we published the follow-up results of 38 survivors out of 87 open abdomen patients treated with negative pressure wound therapy and dynamic fascial sutures between 2007 and 2012. In our current study we present the 10-years follow-up results regarding long-term complications with the focus on incisional hernias and pain. Since 2017 seven more patients have died, hence 31 patients were included in the current study. The patients were asked to answer questions about specific long-term complications of OA treatment including pain, the presence of incisional hernias and subsequent surgical interventions. Demographic data and data regarding fascial closure after open abdomen treatment were collected. All results were analyzed quantitatively. The follow-up period was 8–13 years.

Results: The median age was 69 (30–90) years, and 15 (48.4%) were females. Twenty-four patients (77.4%) responded to the questionnaire: Three patients (12.5%) suffered from pain in the original operating field, all three at rest but not during exercise. None of the patients required analgesic treatment. Eleven patients (45.8%) were found to have incisional hernias. Five out of 11 hernias (45.5%) were treated by surgery and did not declare any pain in the operating field. Among the patients with incisional hernias lower MPI (Mannheimer Peritonitis Index) at the time of primary surgery but more reoperations and treatment days were found. The technique of fascial closure was heterogenic and no differences in the occurrence of incisional hernia could be detected.

Conclusion: The incidence of incisional hernias after open abdomen treatment is still high, but are associated with little pain in the original operating field. Further studies are required to investigate methods for fascial closure techniques after OA treatment.

Dynamic Fascial Closure With Vacuum-Assisted Wound Closure and Mesh-Mediated Fascial Traction (VAWCM) Treatment of the Open Abdomen-An Updated Systematic Review

Introduction: Several different temporary abdominal closure techniques are described in the context of open abdomen treatment. Techniques based on dynamic fascial closure combined with negative pressure therapy have gained popularity and seem to result in the highest fascial closure rates without increased complications and are highlighted in recent guidelines and recommendations. One dynamic closure technique is the vacuum-assisted wound closure and mesh-mediated fascial traction (VAWCM) technique, first described in 2007. The aim of this systematic review was to evaluate the VAWCM technique regarding a number of short- and long-term results.

Materials and Methods: A systematic literature search was performed in PubMed, EMBASE, and Cochrane Library databases for articles published between January 1, 2006 and May 8, 2020. The review was independently performed by the two authors according to the PRISMA statements for reporting systematic reviews and meta-analyses. Results were pooled for presentation of weighted means when applicable.

Results: A total of 220 articles were screened by title and abstract. Thirty-two articles were assessed for eligibility by full-text review and 15 articles finally remained for review. A total of 600 patients treated with VAWCM were included. The pooled weighted means were as follows: fascial closure, 83.5%; enteroatmospheric fistula, 5.6%; planned ventral hernia, 6.2%; in-hospital survival, 72%; and incisional hernia incidence, 40.5%. Long-term survival ranged between 22 and 72%. Quality of life (SF-36) was reported in two studies showing lower scores than the population mean especially in physical domains. Incisional hernia resulted in lower scores in one but not in the other study.

Discussion: The results of 600 VAWCM-treated patients from 15 studies were evaluated in this systematic review. Earlier findings with high fascial closure rates, low enteroatmospheric fistula, and planned ventral hernia rates as well as high incisional hernia incidences were underlined. Permanent mesh for efficient fascial traction and reinforcement at fascial closure seem to be the next step in evolving an optimal temporary closure technique in open abdomen treatment.

Vacuum-Assisted Wound Closure and Permanent Onlay Mesh-Mediated Fascial Traction: A Novel Technique for the Prevention of Incisional Hernia after Open Abdomen Therapy Including Results From a Retrospective Case Series

BACKGROUND AND AIMS

Incisional hernia development is a frequent long-term sequel after open abdomen treatment. This report describes a novel technique, the vacuum-assisted wound closure and permanent onlay mesh-mediated fascial traction for temporary and final closure of the open abdomen, with the intention to decrease incisional hernia rates. Primary aim was to evaluate incisional hernia development and secondary aims to describe short-term complications and patient-reported outcome.

MATERIALS AND METHODS

The basics of the technique is an onlay mesh, applied early during open abdomen treatment by suturing to the fascia in two rows with a 3- to 4-cm overlap from the midline incision, used for traction and kept for reinforced permanent closure. A retrospective case series, including chart review, evaluation of computed tomography/ultrasound images, and an out-patient clinical examination were performed. The patients were asked to answer a modified version of the ventral hernia pain questionnaire.

RESULTS

A total of 11 patients were treated with vacuum-assisted wound closure and permanent onlay mesh-mediated fascial traction with median follow-up of 467 days. Fascial closure rate was 100% and 30 day mortality 0%. Two of nine patients, eligible for incisional hernia follow-up, developed a hernia. Neither of the hernias were symptomatic nor clinically detectable. Six of 10 patients eligible for short-term follow-up had a prolonged wound-healing time exceeding 3 weeks. One of seven patients eligible for patient-reported outcome have had pain during the last week.

CONCLUSION

The vacuum-assisted wound closure and permanent onlay mesh-mediated fascial traction is a promising new technique for open abdomen treatment and reinforced fascial closure. The results of the first 11 patients treated with this technique show a low incisional hernia rate with manageable short-term wound complications and few patient-reported disadvantages.

Successful treatment of enteroatmospheric fistulas in combination with negative pressure wound therapy: Experience on 3 cases and literature review

Enteroatmospheric fistulas (EAF) are rare but challenging and morbid complications of abdominal surgery and require time- as well as resource-consuming management. Furthermore, they severely affect patients' quality of life. Several treatment modalities for EAF management are described in the literature. We describe 3 consecutive cases of EAF treatment by employing negative pressure wound therapy (NPWT) along with either a special silicone fistula adapter or a Silo-Vac-like system in another case to isolate the fistula from the remaining abdominal wound. Spontaneous fistula closure was achieved in 2 of the 3 cases, and surgical resection of the small bowel segment harbouring EAF opening was possible in a third case after wound conditioning. The rate of fistula closure was 100% (n = 3/3). Compartmentalisation of the contaminated area using NPWT accelerated healing of the open abdominal wound remarkably. In summary, we present a useful tool for the challenging management of EAF and review the literature on different treatment options of EAF available today.

Pressure Distribution during Negative Pressure Wound Therapy of Experimental Abdominal Compartment Syndrome in a Porcine Model

(1) Introduction: Negative pressure wound therapy (NPWT) is a frequently applied open abdomen (OA) treatment. There are only a few experimental data supporting this method and describing the optimal settings and pressure distribution in the abdominal cavity during this procedure. The aim of our study was to evaluate pressure values at different points in the abdominal cavity during NPWT in experimental abdominal compartment syndrome (ACS) animal model; (2) Methods: In this study (permission Nr. 13/2014/UDCAW), 27 Hungahib pigs (15.4-20.2 kg) were operated on. ACS was generated by implanting a plastic bag in the abdomen through mini-laparotomy and filled with 2100-3300 mL saline solution (37 °C) to an intraabdominal pressure (IAP) of 30 mmHg. After 3 h, NPWT (Vivano Med^® Abdominal Kit, Paul Hartmann AG, Germany) or a Bogota bag was applied. The NPWT group was divided into -50, -100 and -150 mmHg suction groups. Pressure distribution to the abdominal cavity was monitored at 6 different points of the abdomen via a multichannel pressure monitoring system; (3) Results: The absolute pressure levels were significantly higher above than below the protective layer. The values of the pressure were similar in the midline and laterally. Amongst the bowels, the pressure values changed periodically between 0 and -12 mmHg which might be caused by peristaltic movements; (4) Conclusions: The porcine model of the present study seems to be well applicable for investigating ACS and NPWT. It was possible to provide valuable information for clinicians. The pressure was well distributed by the protective layer to the lateral parts of the abdomen and this phenomenon did not change considerably during the therapy.

Negative pressure therapy versus passive open abdominal drainage for the treatment of septic peritonitis in dogs: A randomized, prospective study

OBJECTIVE

To compare passive open abdominal drainage (POAD) and negative-pressure abdominal drainage (NPAD) using the ABThera™ system in the treatment of septic peritonitis.

STUDY DESIGN

Randomized prospective clinical trial.

ANIMALS

Dogs (n = 16) with septic peritonitis.

METHODS

Dogs with septic peritonitis were randomly assigned to one of two treatment protocols: NPAD versus POAD. Anesthesia time, operating time, duration of drainage, costs, survival, and complications were compared between techniques. Hematological and biochemical parameters in blood and abdominal fluid, and histopathological findings of omentum and abdominal wall tissue samples were compared between NPAD and POAD at time of initial surgery and at time of closure.

RESULTS

Overall survival was 81%. Treatment costs, anesthesia and operating time, drainage time, survival, and postoperative complications were similar between techniques. Loss of total plasma protein and decreased inflammation-related factors in abdominal fluid at time of closure were noted in all patients. Neutrophilic inflammation was greater in abdominal wall samples after NPAD. POAD patients showed discomfort during bandage changes and had frequent leakage of abdominal fluid outside of the bandage.

CONCLUSION

NPAD is an effective alternative to POAD for treatment of septic peritonitis, based on costs and survival. NPAD resulted in less abdominal fluid leakage, and evidence of superior healing on histological evaluation of abdominal tissues.

"Enteroatmospheric fistulae"--gastrointestinal openings in the open abdomen: a review and recent proposal of a surgical technique

The occurrence of an enteric fistula in the middle of an open abdomen is called an enteroatmospheric fistula, which is the most challenging and feared complication for a surgeon to deal with. It is in fact not a true fistula because it neither has a fistula tract nor is covered by a well-vascularized tissue. The mortality of enteroatmospheric fistulae was as high as 70% in past decades but is currently approximately 40% due to advanced modern intensive care and improved surgical techniques. Management of patients with an open abdomen and an enteroatmospheric fistula is very challenging. Intensive care support of organs and systems is vital in order to manage the severely septic patient and the associated multiple organ failure syndrome. Many of the principles applied to classic enterocutaneous fistulae are used as well. Control of enteric spillage, attempts to seal the fistula, and techniques of peritoneal access for excision of the involved loop are reviewed in this report. Additionally, we describe our recent proposal of a lateral surgical approach via the circumference of the open abdomen in order to avoid the hostile and granulated surface of the abdominal trauma, which is adhered to the intraperitoneal organs.

Systematic review and evidence based recommendations for the use of negative pressure wound therapy in the open abdomen

INTRODUCTION

Negative Pressure Wound Therapy (NPWT) is widely used in the management of the open abdomen despite uncertainty regarding several aspects of usage. An expert panel was convened to develop evidence-based recommendations describing the use of NPWT in the open abdomen.

METHODS

A systematic review was carried out to investigate the efficacy of a range of Temporary Abdominal Closure methods including variants of NPWT. Evidence-based recommendations were developed by an International Expert Panel and graded according to the quality of supporting evidence.

RESULTS

Pooled results, in non-septic patients showed a 72% fascial closure rate following use of commercial NPWT kits in the open abdomen. This increased to 82% by the addition of a 'dynamic' closure method. Slightly lower rates were showed with use of Wittmann Patch (68%) and home-made NPWT (vac-pack) (58%). Patients with septic complications achieved a lower rate of fascial closure than non-septic patients but NPWT with dynamic closure remained the best option to achieve fascial closure. Mortality rates were consistent and seemed to be related to the underlying medical condition rather than being influenced by the choice of dressing, Treatment goals for open abdomen were defined prior to developing eleven specific evidence-based recommendations suitable for different stages and grades of open abdomen.

DISCUSSION AND CONCLUSION

The most efficient temporary abdominal closure techniques are NPWT kits with or without a dynamic closure procedure. Evidence-based recommendations will help to tailor its use in a complex treatment pathway for the individual patient.

Wound dehiscence: outcome comparison for sutured and mesh reconstructed patients

PURPOSE

Treatment guidelines for abdominal wound dehiscence (WD) are lacking. The primary aim of the study was to compare suture to mesh repair in WD patients concerning incisional hernia incidence. Secondary aims were to compare recurrent WD, morbidity, mortality and long-term abdominal wall complaints.

METHODS

A retrospective chart review of 46 consecutive patients operated for WD between January 2010 and August 2012 was conducted. Physical examination and a questionnaire enquiry were performed in January 2013.

RESULTS

Six patients were treated by vacuum-assisted wound closure and mesh-mediated fascial traction (VAWCM) before definitive closure. Three patients died early resulting in 23 patients closed by suture and 20 by mesh repair. Five sutured, but no mesh repair patients had recurrent WD (p = 0.051) with a mortality of 60 %. Finally, 18 sutured and 21 mesh repair patients were eligible for follow-up. The incidence of incisional hernia was higher for the sutured patients (53 vs. 5 %, p = 0.002), while mesh repair patients had a higher short-term morbidity rate (76 vs. 28 %, p = 0.004). Abdominal wall complaints were rare in both groups.

CONCLUSIONS

Suture of WD was afflicted with a high incidence of recurrent WD and incisional hernia formation. Mesh repair overcomes these problems at the cost of more wound complications. VAWCM seems to be an alternative for treating contaminated patients until definitive closure is possible. Long-term abdominal wall complaints are uncommon after WD treatment.

Negative pressure wound therapy for the treatment of the open abdomen and incidence of enteral fistulas: a retrospective bicentre analysis

Introduction. The open abdomen (OA) is often associated with complications. It has been hypothesized that negative pressure wound therapy (NPWT) in the treatment of OA may provoke enteral fistulas. Therefore, we analyzed patients with OA and NPWT with special regard to the occurrence of intestinal fistulas. Methods. The present study included all consecutive patients with OA treated with NWPT from April 2010 to August 2011 in two hospitals. Patients' demographics, indications for OA, risk factors, complications, outcome and incidence of fistulas before, during and after NPWT were recorded. Results. Of 81 patients with OA, 26 had pre-existing fistulas and 55 were free from a fistula at the beginning of NPWT. Nine of the 55 patients developed fistulas during (n = 5) or after NPWT (n = 4). Seventy-five patients received ABThera therapy, 6 patients other temporary abdominal closure devices. Only diverticulitis seemed to be a significant predisposing factor for fistulas. Mortality was slightly lower for patients without fistulas. Conclusion. The present study revealed no correlation between occurrence of fistulas before, during, and after NWPT, with diverticulitis being the only risk factor. Fistula formation during NPWT was comparable to reports from literature. Prospective studies are mandatory to clarify the impact of NPWT on fistula formation.

Delayed closure of open abdomen in septic patients is facilitated by combined negative pressure wound therapy and dynamic fascial suture

INTRODUCTION

The aim of this prospective controlled trial was the definition of the optimal timepoint for delayed closure after negative pressure wound therapy (NPWT) in the treatment of the open abdomen (OA) in septic patients after abdominal surgery. The delayed closure of the abdominal wall after abdominal NPWT treatment is often problematic due to the lateralization of the fascial edge leading to unfavorably high tensile forces of the adapting sutures in the midline. We present the results of an innovative combination of NPWT with a new fascial-approximation technique using dynamic fascial sutures (DFS) and delayed closure of the abdominal wall.

METHODS

Eighty-seven patients subjected to OA therapy following surgery for secondary peritonitis were treated with NPWT and DFS. In all patients, a running suture of elastic vessel loops was used to approximate fascial edges. This procedure was continued for the duration of NPWT until final closure of the abdomen with running suture in 55 patients (63.2 %) and interrupted suture technique in eight patients (9.2 %). An anterior component separation was performed in seven patients.

RESULTS

Delayed closure was achieved in 68 patients (78.2 %) after 12.6 days [mean (SD) 25.1 (2-204)] days and 4.3 re-operations [mean (SD) 6.0 (1-43)]. Fifteen (17.2 %) superficial and two (2.3 %) deep wound infections occurred. In three (3.4 %) cases, entero-atmospheric fistulas had to be treated. We recorded no technique-specific complications. Four (5.9 %) incisional hernia were detected in a mean follow-up of 40.5 months (16-65). Mortality rate was 55.2 %.

CONCLUSION

Using a new technique combining NPWT and DFS in the treatment of the OA, the delayed closure of the fascial edges by running suture can be achieved and the number of re-operations can be kept low. The technique was safe and led to a low incidence of incisional hernias. Extensive abdominal wall reconstruction was seldom required.

Options for closure of the infected abdomen

BACKGROUND

The infected abdomen poses substantial challenges to surgeons, and often, both temporary and definitive closure techniques are required. We reviewed the options available to close the abdominal wall defect encountered frequently during and after the management of complicated intra-abdominal infections.

METHODS

A comprehensive review was performed of the techniques and literature on abdominal closure in the setting of intra-abdominal infection.

RESULTS

Temporary abdominal closure options include the Wittmann Patch, Bogota bag, vacuum-assisted closure (VAC), the AbThera™ device, and synthetic or biologic mesh. Definitive reconstruction has been described with mesh, components separation, and autologous tissue transfer.

CONCLUSION

Reconstructing the infected abdomen, both temporarily and definitively, can be accomplished with various techniques, each of which is associated with unique advantages and disadvantages. Appropriate judgment is required to optimize surgical outcomes in these complex cases.

The open abdomen and temporary abdominal closure systems--historical evolution and systematic review

AIM

Several techniques for temporary abdominal closure have been developed. We systematically review the literature on temporary abdominal closure to ascertain whether the method can be tailored to the indication.

METHOD

Medline, Embase, the Cochrane Central Register of Controlled Trials and relevant meeting abstracts until December 2009 were searched using the following headings: open abdomen, laparostomy, VAC (vacuum assisted closure), TNP (topical negative pressure), fascial closure, temporary abdominal closure, fascial dehiscence and deep wound dehiscence. The data were analysed by closure technique and aetiology. The primary end-points included delayed fascial closure and in-hospital mortality. The secondary end-points were intra-abdominal complications.

RESULTS

The search identified 106 papers for inclusion. The techniques described were VAC (38 series), mesh/sheet (30 series), packing (15 series), Wittmann patch (eight series), Bogotá bag (six series), dynamic retention sutures (three series), zipper (15 series), skin only and locking device (one series each). The highest facial closure rates were seen with the Wittmann patch (78%), dynamic retention sutures (71%) and VAC (61%).

CONCLUSION

Temporary abdominal closure has evolved from simple packing to VAC based systems. In the absence of sepsis Wittmann patch and VAC offered the best outcome. In its presence VAC had the highest delayed primary closure and the lowest mortality rates. However, due to data heterogeneity only limited conclusions can be drawn from this analysis.