Biological Mesh Combined With Topical Negative Pressure Therapy in Complex Abdominal Wounds: A Short Series and a Review of the Literature

Introduction. Complex abdominal wounds (CAWs) are an increasing clinical problem in abdominal surgery and pose a challenge for the surgeon. Objective. This review analyzes the results of treating CAWs with a porcine biological mesh and topical negative pressure (TNP) to address the feasibility, effectiveness, level of risk, and overall results. Materials and Methods. A series of 4 consecutive cases treated with the biologic mesh and TNP at the General Surgery Unit of the Cannizzaro Hospital (Catania, Italy) is reported and analyzed. In addition, a review of the literature published in all languages from 2000 to 2015 in the MEDLINE/PubMed database was performed to identify cases of CAWs treated with the association of biologic mesh and TNP. Results. Taking into account the authors’ experience and review of literature, a total of 12 patients (4 treated in the authors’ department) were treated with the aforementioned combination. The main indications for using this association were a large abdominal wall defect, laparotomy, or wound dehiscence and wound infection. In almost all cases, this combination demonstrated a successful outcome with a clear improvement in wound healing and no adverse effects. Conclusions. From these cases and the review of the literature, the authors believe TNP can be applied on a biological mesh with effectiveness in improving the treatment of the CAWs without relevant risk to the patient or biological mesh.

General surgeons have to deal with increasing clinical problems for both primary and secondary abdominal wall defects, especially if they are combined with local infection. These cases are generally defined as complex abdominal wounds (CAWs). Despite the advances in new technological support and improvement of different available devices for the treatment of CAWs, a statistical analysis of experimental and/or clinical combinations of individually tested devices is impossible due to the variability of these cases.¹ Therefore, experience, empirical clinical experimentation, and detailed reports of used treatments for these complex cases remain the only opportunity for a contribution to the progress of medical practice. 

Chronic abdominal wounds represent a challenge for surgeons, especially because they have to deal not only with patient expectations regarding quick and complete healing but also their comorbidities. Furthermore, a CAW is difficult to treat because multiple factors contribute to the alteration of the normal healing process and are often the cause of a wound’s spontaneous dehiscence.² Sometimes, a major abdominal wall defect also can be the consequence of a still-existing incisional hernia.³ Aiming to manage these often life-threatening situations, surgeons have adopted and implemented different methods, including older techniques such as the Wittmann Patch, Bogota bag, and packing.⁴

Despite all of these possibilities, the incidence of complications remains high⁴ (eg, incisional hernia, evisceration, cutaneous fistulas, seromas, and local infections), all leading to abnormal repair processes that result in prolonged hospital stay and increased costs. Currently, there is the possibility of using and combining some of the different techniques, solutions, and sophisticated devices such as those based on topical negative pressure (TNP; ACTIV.A.C. Therapy System [KCI, an Acelity Company, San Antonio, TX] with biological mesh), but unfortunately the effectiveness and risks of this combination are not widely described in the literature, as evidenced by the present review. Separately, TNP⁵ and the biological mesh⁶ have been effective in treating CAWs, but there are no clinical data, studies, or retrospective reviews concerning this combination. Moreover, the aforementioned products are expensive. Any data concerning the effectiveness of their combined use that demonstrates their possible implementation and positive results and indicates a significant reduction in hospital stay (thus overall costs) would be very important. Herein, the authors analyzed a short series of patients treated with this combination showing positive results and included a review of the literature to clarify its effectiveness.

At the General Surgery Unit and Emergency Department of the Cannizzaro Hospital (Catania, Italy), a total of 26 patients consecutively received a biologic mesh. Of those, 4 cases (15.4%) with CAWs and complex clinical situations were treated with a combination of the biological porcine mesh (Permacol Surgical Implant; Medtronic, Minneapolis, MN) and the TNP device without any interface between them. In these patients, a second surgical operation of flap closure was avoided because of patient history of postoperative wound infection, diabetes (75% of patients), and poor general conditions (eg, not well-controlled diabetes and hypertension). All data concerning technique, management, feasibility, effectiveness, problems, risks, and overall results were recorded and analyzed. 

Materials

The TNP device is a nonpharmacological method of treatment, using dedicated sponges encapsulated in sheets of plastic material that takes advantage of the mechanical principle of the TNP. Application of the negative pressure in a continuous or intermittent manner is a recognized method^7,8 to improve and facilitate the healing process of different types of wounds. The biological porcine mesh consists of cross-linked porcine dermis usually adopted in difficult local conditions, such as an infection.

Literature review

Based on the evidence of limited worldwide clinical experience, the authors reviewed the literature on this particular association. Articles published in any language from 2000 to 2015 in the MEDLINE/PubMed database were searched; biological mesh was not available prior to 2000. The keywords used in the search included “abdominal wound,” “infection,” “topical negative pressure,” “vacuum assisted therapy,” “closure,” “biologic mesh,” and “complications.” All details available from the articles (including indications for type and size of the biological mesh, method of placement, and method of fixation) and all available data relevant to TNP therapy (ie, time, duration, method, complications, outcome, follow-up, and negative effects concerning TNP on the biological mesh) were analyzed.

Of the 26 patients who received a biologic mesh, 4 (15.4%) received the combination treatment of biologic mesh and TNP (Figures 1,2; Table 1). In this group of patients, there were 3 women and 1 man, with a mean age of 63.5 years (range, 55–71 years). 

In all 4 patients, the main criterion for using this mesh was a large defect in the abdominal wall due to a pre-existing median incisional hernia in an infected area (3/4 patients; 75%) or a previous surgical intervention with the onset of wound healing complications (1/4 patients; 25%). In all patients, the biological mesh was used to close the defect of the abdominal wall, with an appropriately sized piece of mesh (20 cm x 15 cm in 2 cases, 10 cm x 15 cm in 2 cases). In 3 cases, the mesh was placed with the underlay technique and 1 case with the inlay technique, with an overlap of 3 cm to 4 cm and fixed to the musculofascial plane with a tailored approach using 4-quarter continuous sutures (ETHIBOND EXCEL Polyester Suture; Johnson & Johnson, New Brunswick, NJ) in 2 cases and an interrupted suture with propylene in the other 2 cases. 

In all 4 cases, the postoperative course was marked by the development of wound infections, with complicated healing also due to underlying concurrent risk factors (eg, diabetes in 75% of patients). All patients underwent multiple local sampling for microbiological cultures of the infected wounds. In 2 cases (50%), pathologic colonies of methicillin-resistant Staphylococcus aureus (MRSA) always associated with Staphylococcus epidermidis were found; 1 patient was positive only for S epidermidis, while another patient tested positive for Escherichia coli. All patients were treated with targeted antibiotic therapy. 

TNP therapy

In all 4 patients following surgical wound debridement, evidence of infection with relevant exudation and worsening of local conditions of the fascia, subcutaneous, and cutaneous tissues led to the decision to add TNP with the hope of reducing the negative impact of infection on the mesh and closing the wound. The TNP device was positioned as per manufacturer specifications. The film-encapsulated sponge was placed directly on the biological mesh after cutting it with scissors to obtain the best possible fit over the defect in the cutaneous/subcutaneous layer of the abdominal wall. The negative pressure of the TNP unit was used variably in continuous or intermittent mode, with pressure values between -50 mm Hg and -125 mm Hg. During the first 1 to 3 weeks, the suction mode was set continuously and then progressively reduced to minimal pressure and switched to intermittent mode in the weeks following. The suction mode also was adapted and changed depending on the daily amount and macroscopic features of the collected fluid from the wound. The complete replacement of the TNP dressing and sponge was scheduled every 3 to 4 days, according to the amount of collection, to avoid the increased risk of infection and damaging the mesh by more frequent changes. 

During the first 3 weeks, the changes took place in the operating room for repeat surgical debridement to be performed in a sterile environment when necessary; after relevant improvement, dressing changes were made at the bedside. This schedule was delayed up to 6 days, according to an evaluation of the patient’s general condition, especially when sepsis was excluded and also based on simple factors suggesting an improvement in the healing of the tissues (namely the amount of collected fluid). Another factor of delaying up to 6 days was the macroscopic feature of the fluids suggesting the reduction of infection, specifically a noted progressive clearance from purulent gray to clear and serous fluid. 

The application of TNP resulted in a clear improvement in wound healing with a reduction of local and general signs of inflammation within 1 to 2 weeks for all patients (Figure 3). Two patients achieved complete wound closure within 49 days, while the remaining 2 patients demonstrated a clear and progressive macroscopic improvement of the abdominal wound until their death (6 and 11 weeks postoperatively). Mortality was caused by major cardiovascular or respiratory complications (unrelated to wound care treatment) despite the improvement of the abdominal wound. 

None of the patients showed a negative evolution on the wound. No problems or damage to the biologic mesh due to the TNP were observed (Figures 4, 5, 6). Two patients completed their follow-ups after complete wound closure and hospital discharge between 24 and 52 days postoperatively. At follow-up weeks 12 and 108, the 2 patients showed optimal surgical results without disruption of the biological mesh and no evidence of recurrence of the incisional hernia.

Literature review

The review of the literature identified 7 studies (Table 2): 5 case reports^2,9-12 and 2 clinical experiences with cases reported.^13,14 Within these 7 studies, there is a combined total of 8 cases using the biological mesh with TNP therapy for the treatment of CAWs from 2000 to 2015. 

In the 8 cases, the mean patient age was 58.4 years (range, 48–79 years). The main indication for the combined use of TNP therapy with biological mesh was local infection (50%, 4/8 cases) due to MRSA, Pseudomonas species, Corynebacterium, Staphylococcus, and Enterococcus. Wound dehiscence was reported in 87.5% of cases; only 1 case¹¹ (12.5%) reported this association to be adopted for a large wall defect with a high risk of compartment syndrome. With reference to surgical technique, only 2 cases (25% excluding the present 4) included the details regarding the positioning of the mesh (inlay/bridge technique in 4cases,^2,9-11 and sublay in 2 cases¹³ but not given in the remaining 2 cases^12,14). Concerning the method of the fixation of the mesh, only 3 studies reported a description of the suture: absorbable continuous suture,⁹ nonabsorbable stitches,² and interrupted nonabsorbable suture.¹³ 

Only 4 cases (50%)^2,9,13 reported the value of the negative pressure, ranging between -50 mm Hg and -125 mm Hg. The frequency of medications with substitution of the devices for the TNP was described in 3 cases (37.5%),^2,13 in which dressing changes happened every 3 to 4 days but was not indicated whether it was conducted in the operating room or at the bedside. Data on follow-up are reported in all papers, with a mean follow-up time of 14.12 weeks (range, 2–25 weeks). 

In all 8 cases of this combination treatment, no complications or relevant clinical problems were reported. In addition, no studies (0%) reported negative effects or damage by the TNP on the mesh. The conclusions drawn by some authors of the collected cases^2,9,12,14 agree this combination treatment plan showed favorable patient outcomes. In addition, they^2,9-14 underline the feasibility and effectiveness of this combination for the treatment of CAWs, especially when infection is present. With adding the previously presented 4 patients, the authors herein can report on a total of 12 patients; this is the largest collection of cases published on TNP with biological mesh in CAWs.

The main local factors preventing surgeons from closing the abdominal wall are infection, wall defect, evisceration, or technical difficulty in suturing due to exaggerate tension. Moreover, in life-threatening cases, such as peritonitis, abdominal compartment syndrome,¹⁵ laparotomy, and wound dehiscence, which has a mortality rate of up to 45%,¹⁶ the surgeon has to decide when and how to close the abdominal wall to manage and/or prevent a CAW. These methods may include older techniques (eg, Wittmann Patch, Bogota bag, packing, or skin only up to the “open abdomen”^17,18) and also the most recently available products, such biological meshes and/or, in particular cases, in combination with TNP therapy. Despite all these possibilities, the risk of complications remains high, including evisceration, cutaneous fistulas, abundant loss of fluids, seromas, and especially local infections, all leading to abnormal repair processes that can cause prolonged hospital stay and increased overall costs.⁴

Postoperative wound infection normally appears in a surgical wound within 30 days to 1 year following surgery with cases involving an implanted prosthesis.^18-20 Surgical site infections (SSIs) remain the second most frequent type of health care-associated infection (HAI) in Europe and the United States,²¹ with SSIs accounting for 20% of all HAIs in hospitalized patients.²² The World Health Organization has shown HAIs are connected to an increased morbidity, mortality (can exceed 10% with certain infections²³), hospital stay, and total costs.²⁰ In particular, prolonged hospital stay for SSIs was an additional 9.7 days and extra inpatient hospital costs ranged between $1087 and $29 443 per infection.^21,24 According to the National Nosocomial Infections Surveillance System (NNIS), the distribution of pathogens in surgical infections seems to have changed in the last 10 years.^20,25 The most frequently isolated bacteria are S aureus, followed by coagulase-negative staphylococci, E coli, E faecalis, Pseudomonas aeruginosa, Enterobacter spp, and Klebsiella.²¹ Some of these were also the main infections found in the present review, which suggests prevention is mandatory.

TNP therapy

Using devices like TNP represents a nonpharmacological treatment for normally infected CAWs. The working principles of negative pressure wound therapy are based on the physical principle of applying a negative pressure aimed at retrieving and collecting fluids produced by inflamed wounds. This process favors the progressive reduction in size of the vital margins of the defect by retraction, and often protects the intraabdominal organs.²⁶ The application of this TNP and aspiration produce positive extracellular, cellular, and complex effects. The extracellular effects (1) improve blood flow, thus increasing the perfusion of subcutaneous tissues and dermis (improved with negative pressures between -75 mm Hg to -125 mm Hg, unlike that observed with stronger pressures of -400 mm Hg)²⁷; (2) reduce edema of the tissues^27,28; and (3) remove fluids from the wound containing substances such as proteolytic matrix metalloproteinase (MMP) 1, MMP-2, and MMP-9.^27-29 The cellular effects are due to the mechanical stress of the foam interface on the wound that causes angiogenesis and vasculogenesis, mediated by factors such as hypoxia-inducible factor 1-alpha,²⁹ and retraction of the wound.³⁰ The main complex effect is the reduction in the bacterial load in the wound bed.^27,31,32

It is important to note that TNP treatment is not free of complications, and the dominant discussion concerns the onset of enterocutaneous fistula.^33,34 However, in some studies, such as that reported by Woodfield et al,³⁵ TNP therapy itself was used in the management of 5 cases of fistula. The costs and benefits TNP therapy are still uncertain, thus randomized comparative studies are necessary to support its use.²⁶

Biological mesh

A biological mesh is used in attempt to close the abdominal wall in a tension-free manner in an infected field or in one that is suspected of being infected. Today, the most utilized meshes are STRATTICE Reconstructive Tissue Matrix (Allergan, Dublin, Ireland), Surgisis/Biodesign Mesh (Cook Medical, Bloomington, IN), AlloDerm (Allergan), and Permacol.³⁶ The last (the studied biological mesh) consists of a matrix of a cellular porcine dermal collagen first used in the United Kingdom in 1998 and thereafter approved by the US Food and Drug Administration in 2000. Although all xenograft biologic meshes provide a bioscaffold, not all undergo similar processing techniques and, as a result, are remodeled differently.³⁷ Overall, in the literature, there is no consensus on the bodily reaction to the different types of meshes. For instance, Mulier et al³⁷ found Permacol (crosslinked) and STRATTICE (non-crosslinked) had endovascular in-growth and host collagen infiltration. On the other hand, Novitsky et al³⁸ reported enhanced inflammatory response and profound foreign body reaction are responsible for the encapsulation and poor host integration of the crosslinked biological meshes. In addition, Deeken et al³⁹ demonstrated that crosslinked materials caused greater fibrous encapsulation in the first 6 months, though the studied mesh's materials exhibited a substantial decrease in encapsulation between 6 and 12 months, making it similar to the non-crosslinked materials by 12 months. It is undoubtedly true that the combination of the aforementioned treatments, namely biologic mesh with TNP, is based on appropriate scientific and pathophysiological basis. However, only empirical clinical experience can help clarify the issue and determine the best way for this association to improve the results in the treatment of CAWs. 

This study has a small number of cases due to the uncommon association of TNP therapy and biological mesh. This unusual combination is demonstrated by the few articles that were found in literature. The low number of reported cases could be attributed to the fact that companies producing biologic mesh and TNP devices have not provided clear instructions on how to combine them. Moreover, the use of biologic mesh and TNP is relatively recent, which also explains the few cases reported and supports the importance of the cases the present authors add. Although the number of cases is a limitation, the authors believe it is also a strength of this article due to the unique combination they highlight in the literature.

This is the first report to include a total of 12 cases collected by both the authors’ personal experience and results from the literature review. The important aspect of the substantial economic cost of the combined use of these expensive devices remains controversial. Though that should have limited importance when considering the high priority to heal wounds quickly in fragile patients. The feasibility, safety, and effectiveness of this combination demonstrated here, as well as the reduction in healing time and shortened length of hospital stay, certainly result in a significant decrease in overall costs. To definitively clear these economic aspects, controlled prospective studies should be carried out; however, the authors feel these would be very difficult to conduct due to the rarity and extreme variability of CAW cases. 

Authors: Elena Schembari, MD¹; Antonio Santangelo, MD²; Antonio Pesce, MD¹; Maurizio Mannino, MD¹; Sofia Maria, MD³; Domenico Russello, PhD¹; Saverio Latteri, MD¹; and Gaetano La Greca, PhD¹

Affiliations: ¹Department of Medical and Surgical Sciences and Advanced Technologies “GF Ingrassia,” University of Catania, General Surgery Unit, Cannizzaro Hospital, Catania, Italy; ²Università degli Studi di Udine, Medical, Via Pozzuolo, 330, 33100 Udine UD, Italy; and ³General Surgery Unit, Cannizzaro Hospital

Correspondence: Antonio Santangelo, MD, Università degli Studi di Udine, Medical, Via Pozzuolo, 330, 33100 Udine UD, Italy; santangelo-a@libero.it

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