Negative Pressure Wound Therapy of Open Abdomen and Definitive Closure Techniques After Decompressive Laparotomy: A Single-center Observational Prospective Study

Introduction. Open abdomen is a concept that was developed especially in relation to abdominal compartment syndrome (ACS). Objective. This study presents the evolution and complications related to the management of the open abdomen after decompressive laparotomy, using a standardized method based on negative pressure wound therapy (NPWT). Materials and Methods. This observational prospective study conducted over a 9-month period included 19 patients who underwent decompressive laparotomies for ACS. The triggering conditions were peritonitis, infected and noninfected acute pancreatitis, ileus, and trauma. Temporary abdominal closure was performed using NPWT and the final closure by primary suture or dual mesh. Intra-abdominal pressure was permanently and indirectly monitored transvesically. Results. After decompressive laparotomy, the intra-abdominal pressure decreased significantly (P < .001) compared with the value preoperatively (41.4 mm Hg to 15.3 mm Hg). Mortality was 21.2%, with higher rates for acute pancreatitis (odds ratio [OR] = 3.75) and trauma (OR = 1.25) due to the severity of the primary illness. The final closure was performed after 11.7 days, and primary closure was possible in 4 cases. Conclusions. Decompressive laparotomy significantly reduced intra-abdominal pressure for ACS, improving the prognosis.

According to the World Society of the Abdominal Compartment Syndrome (WSACS), the notion of open abdomen means a temporary laparostomy with subsequent closure of the musculoaponeurotic wall and of the skin.¹ The history of open abdomen began in the last century with the first descriptions by McCosh² and Ogilvie,³ and detailed articles were published in the 1980s.⁴ After the 1980s, the initial concern of surgeons was strictly linked to the management of the externalized intestines in the peritoneal cavity.⁵ The early abdominal closure procedures described were highly complicated, included the preparation of myofascial flaps, and were encumbered by many postoperative complications.⁵ Over time, besides temporary abdominal closure (TAC) management, increasingly efficient techniques to reduce the lateral musculoaponeurotic retraction appeared, eventually leading to the description of cases with subsequent myofascial primary closure.⁶ The ideal TAC should be easy to perform and allow quick access into the peritoneal cavity so that it may increase the success rate of primary closure and ensure fewer complications.⁷

This paper shows the evolution and complications of open abdomen using a standardized management method, based on negative pressure wound therapy (NPWT), after performing decompressive laparotomies (DLs) as a therapeutic solution to abdominal compartment syndrome (ACS). Decompressive laparotomy is the final stage of ACS treatment and is often not performed. For this reason, the number of patients included in the study is low, but it is high enough to draw proper conclusions, taking into consideration that these are critical patients with severe abdominal disease, organ failure, and peripheral hypoperfusion.

This article contains 2 observational studies, 1 prospective and the other retrospective.

Prospective study design

This was a longitudinal, observational prospective study. Prior to approval by the ethics committees of the Clinical Emergency County Hospital of Târgu Mureș (Târgu Mureș, Romania) and the University of Medicine and Pharmacy of Târgu Mureș (Târgu Mureș, Romania), it was registered as study No. 118/22 in January 2016. Informed consent was obtained from each patient; for comatose patients, consent was given by relatives, according to Romanian state legislation.

The study took place between January 2016 and September 2016 and included 19 patients who underwent DL, taken from a total of 66 patients monitored after developing ACS (Figure 1). Inclusion criteria consisted of those with primary and secondary ACS and a lack of response to the specific conservative treatment (in accordance with the WSACS guidelines) within 24 hours. Exclusion criteria included those with ACS with good response to medical treatment as well as those with isolated intra-abdominal pressure (IAP).

Decompressive laparotomy and open abdomen management

Decompressive laparotomy was performed within the first 24 hours by a midline incision above and below the umbilical orifice, with enough to release the loops and epiploon from the peritoneal cavity. From the start, the subsequent TAC management was dictated using a negative pressure continuous suction system with 2 roles: aspiration of collections and reduction of intra-abdominal tissue edema, thus avoiding musculoaponeurotic retraction of the wound edges and the induction of granulation tissue. To this end, the VivanoMed Abdominal Kit (HARTMANN, Heidenheim an der Brenz, Germany) was used; the entire system assembly consisted of the VivanoTec Unit (HARTMANN) and consumables. The single-use abdominal kit contains mesh to protect the viscera with a 65-cm diameter fitted with superior pockets to facilitate insertion, 2 polyurethane foam dressings of 38 cm × 25 cm × 1.6 cm, 1 suction port, and hydrofilm strips for sealing.

Immediately after DL, the intestines and epiploon were protected by inserting the mesh from the kit described above into the upper interhepatophrenic spaces, laterally into the flaps towards the right and left parietocolic grooves, and into the posterior plane behind the urinary bladder. On top of the mesh, polyurethane foam was mounted in 2 or 3 layers by adjusting the dimensions of the dressings to the incision. After installing sealing strips over the entire wound without creating tension, the suction port connected to the collection tank was secured. The device was originally set to a gentle pressure of -105 mm Hg in order to avoid possible intra-abdominal bleeding or bleeding at the wound edges. The dressings were changed every 2 to 3 days using the abdominal kit if the patient’s condition was critical with maintained ACS.

After a third change of the abdominal kit, due to the appearance of the granulation tissue covering the omentum, bowels, and wound margins, the pressure was reduced to -135 mm Hg (as per manufacturer’s recommendation) and the process continued in the same manner until final closure.

Subsequently, given favorable developments, the reconstruction of the abdominal wall was performed by primary myofascial closure or using a substitute dual mesh (polyester and dimethyl siloxane; Intramesh; Cousin Biotech, Wervicq-Sud, France) sutured on the musculoaponeurotic edges with Prolene 3.0 (Ethicon Inc, a Johnson & Johnson company, Bridgewater, NJ) continuous threads secured via 10 separate suture points (Figure 2).

From the ACS diagnosis up to the final closure, the IAP was monitored by an indirect transvesical measurement using a dedicated kit (AbViser AutoValve Intra-Abdominal Pressure Monitoring Device 331; ConvaTec, Bridgewater, NJ). All procedures (temporary closure, the initiation of NPWT, dressing changes, and definitive closures) were performed in the operating room.

In all cases, after a proper lateral mobilization of the skin, the definitive closure required no skin grafts. In 1 case, following the appearance of a small area of skin necrosis, excision and secondary suture were necessary.

Patient follow-up took place during the 6 months after discharge, and, in months 1, 3, and 6, included clinical and imaging checks (use both the abdominal cavity and wall ultrasound and computed tomography scan) for intra-abdominal collections and the integrity of the abdominal wall.

Retrospective observational study design

In order to increase the impact of the study, the investigators performed a simultaneous retrospective study by collecting data from patients who had undergone open abdomen management before the introduction of NPWT. Therefore, 21 files from the previous 2 years were analyzed in relation to patients who had been admitted to the same clinic and who required open abdomen for the same primary diseases: peritonitis caused by enteral fistulas (8 cases), infected necrotizing pancreatitis (10 cases), trauma (2 cases), and frozen abdomen (1 case). The TAC was performed using plastic film over the open abdomen.

Wound care was performed in the operating room, with 11 patients receiving intravenous anesthesia and 10 patients receiving local lidocaine wound instillation. Primary suture was possible in the 2 cases with abdominal suture without meshes after abdominal trauma. In 5 cases (2 cases of enteral fistula and 3 cases of acute pancreatitis), definitive closure was performed using substitutive polipropilene mesh over the great omentum and attached to the muscular wound margins. Due to wound edge lateral retraction and continuous wound secretions, it was impossible to achieve the definitive abdominal closure in 6 cases (3 enteral fistulas and 3 acute pancreatitis) using just the skin flaps; those patients developed a conducted incisional hernia. Local wound complications were encountered in 16 of the 21 patients (76.19%), with a mortality rate of 47.61%.

All statistical calculations were performed using GraphPad software (GraphPad; San Diego, CA). The investigators tested the normal distribution for a continuous variable using the Kolmogorov-Smirnov test. They characterized the distributions using the mean and standard deviation (SD) for variables with a normal distribution, or the median and range for variables with a non-normal distribution. According to data distribution, adequate statistical tests were chosen. Differences in mean age by gender were determined using Student’s t test. The statistical analyses of IAP, mortality, and DL results were performed using the analysis of variance (associated with the Bonferroni multiple comparison test).

In a box-and-whisker plot, the central box represents the values from the lower to the upper quartile (25th to 75th percentile); the middle line represents the median. A line extends from the minimum to the maximum value. All tests were interpreted relative to the significance threshold of P = .05, and the results were considered to be statistically significant for P < .05.

Prospective study

The average age in the prospective study group was 66.63 years (range, 49–78 years; SD = 10.11). Of the 19 patients, there were 13 men (68.42%) and 6 women (31.58%). The IAP decreased significantly (P < .001) compared with the initial value after DL (Figure 3).

The overall mortality rate was 21.05%. The causes of death included septic shock in 2 cases (acute infected pancreatitis and generalized peritonitis after perforated diverticulitis), 1 case of respiratory failure following infected pulmonary contusion after trauma, and 1 case of respiratory failure following bronchopneumonia in a patient with infected pancreatitis and chronic obstructive pulmonary disease. Mortality could be correlated with the type of disease that triggered ACS, being higher (without statistical significance) in infected acute pancreatitis and abdominal trauma (Table 1).

The complications during TAC consisted of 2 wound suppurations in patients who had undergone surgeries for generalized peritonitis after colorectal anastomosis fistula and 1 intestinal obstruction due to adhesions in a patient with a frozen abdomen. With respect to the wound suppurations, they evolved favorably by using NPWT associated with the general treatment, and with respect to the occlusion, resurgery was performed and the adhesions dissolved. The final closure of the abdomen was performed after a mean time of 11.7 days (range, 9–14 days). The closure type was primary suture of the musculoaponeurotic edges in 4 cases and the use of dual mesh in the other 11 cases. The average duration of the patient’s hospitalization was 24.7 days.

After the final parietal closure, 1 patient needed split-thickness skin grafting for a presacral eschar. At 1-month postop follow-up, none of the patients showed any clinical or ultrasound defects of the abdominal wall.

Retrospective study results

Primary suture was possible in the 2 cases of abdominal trauma. In 5 cases (2 cases of enteral fistula and 3 of acute pancreatitis), definitive closure was performed using substitutive polypropylene dual mesh over the great omentum and attached to the muscular wound margins. Due to the lateral retraction of the wound edges and continuous wound secretions, it was impossible to achieve definitive abdominal closure in 6 cases (3 cases of enteral fistula and 3 of acute pancreatitis); thus, only skin flaps were used, leading to those patients developing a planned incisional hernia.

Local wound complications were encountered in 16 of 21 patients (76.19%), with a mortality rate of 47.61%. The statistical analysis results of the 2 studies are shown in Table 2. The average days of hospitalization, wound suppuration, and planned incisional hernia rates were statistically significantly decreased.

Open abdomen indications are diverse, and many are related to traumatic injuries (Table 3^12-14). Decompressive laparotomy is of particular importance in ACS, reducing the mortality caused by the disease by between 16% and 37%.^8-11

Various solutions for open abdomen have developed along with the evolution of this new therapeutic concept of TAC. Among the many surgical variants for TAC, only a few have been incorporated into standard medical practice.⁶ The simplest and cheapest is merely closing the skin over the viscera using clip clamps, allowing quick and easy access to the peritoneal cavity whenever needed. The disadvantages of this process are that the affronted skin may cause pressure on the gutted organs, and it does not prevent lateral musculoaponeurotic retraction.¹⁵ The Bogota method, or plastic-bag closure, consists of covering the intestinal loops in a plastic film made on the spot, depending on the size of the wound, from saline-solution bags or urine-collection bags. These are fixed by both the musculoaponeurotic edges and the skin.¹⁶ The Wittmann technique consists of mounting 2 overlapping sheets of Velcro (London, UK), sutured on the musculoaponeurotic edges, on both sides. After each inspection of the abdominal cavity, the position of the foils will be readapted to return them towards the midline of the aponeurotic edges.¹⁷ The method of wound aspiration by creating negative pressure has been proven to have the best results,¹² accomplishing several of the goals of TAC management: suctioning secretions, isolating the wound, and musculoaponeurotic closure with wound orientation towards myofascial primary closure. After the procedure performed by Brock et al in 1995, the development of dedicated NPWT kits was initiated.^18,19 The TAC approach using NPWT technique also has been in the WSACS recommendation since the 2013 consensus.¹ Nowadays, it has a 1B grade indication for open abdomen management.¹⁴ In the cases presented herein, the chosen solution was a negative pressure continuous suction system (eFigure 4).

Initially appearing as a separate method, the use of meshes to prevent lateral retraction was subsequently combined with NPWT techniques, eg, polydioxanone mesh plus NPWT,²⁰ polypropylene plus NPWT,²¹ or the ABRA Abdominal (Southmedic, Barrie, Ontario, Canada) system, the combination of transfascial elastomeric fibers tensed with buttons placed on the skin, with NPWT.²² All these techniques have significantly increased the percentage of late myofascial closure by up to 100%, according to research.²³

The final closure of the abdominal wall should be done without tension. Depending on the TAC technique used, primary fascial closure varies. In this reported study, it could be carried out in 4 of the 19 cases. Closure without tension can be achieved using meshes.²⁴ If visceral protection with epiploon can be performed, or if the granulation tissue is sufficiently well developed after NPWT, polypropylene meshes can be used.²⁵ Safe alternatives are dual meshes made from polypropylene, polyester, or expanded polytetrafluoroethylene, which can be sutured to the aponeurotic edges and applied safely over the viscera.²⁶ Biological materials offer a possible solution, but they are laborious and can give rise to postoperative complications due to graft necrosis (Table 3^12-14).^27,28 Modern cross-linked and noncross-linked meshes manufactured in the laboratory are currently very expensive, thus, they should only be used in reserved cases.²⁹ In the present study, the investigators had very good results with fewer complications using polyester-dimethyl siloxane dual mesh.

After introducing the concept of open abdomen management in 2009, Björck and Wanhainen presented a classification system, later revised in 2013, that takes into consideration the origin of the open abdomen and the therapeutic attitude (Tables 4^6,30-33, 5³⁴). The application of this classification in the investigators’ study could be correlated with the patients’ prognosis, local complications, and mortality rate.

The open abdomen in ACS is a particular entity, as both the pathophysiological cascade of ACS and the disease that caused it must be treated, even if it seems a desperate and difficult solution to manage later, both in terms of the temporary and the permanent closure. Decompressive laparotomy is today part of the ACS treatment algorithm established by WSACS.¹ As conservative treatment shows good results in a proportion of patients developing ACS, DL is rarely performed. Cheatham and Safcsak³⁵ conducted a study on 265 patients with ACS, in which only 31 patients needed DL.

The limitations of this study are related to the small number of patients (19 patients), despite the fact that the intensive care unit is the largest in Transylvania and the Major Emergency Room Center covers an area with a population of 5.8 million residents.

In the complex treatment of ACS, DL is a necessary therapeutic solution to improve prognosis. Decompressive laparotomy aims both to release the IAP and treat the underlying disease. The open abdomen management was based on eliminating secretions, protecting the viscera, and avoiding lateral musculoaponeurotic retraction. Negative pressure wound therapy was utilized in all cases, as recommended by the WSACS Guidelines of 2013.¹ Compared with the observational retrospective study group, NPWT increased the primary and definitive closure rate and reduced local complications and the number of days of hospitalization. The mortality rate was decreased (but not statistically significantly) due to the favorable effect of NPWT on the primary disease, thus eliminating the abdominal secretions and avoiding collections in the septic abdomen.

Affiliation: University of Medicine and Pharmacy of Tîrgu Mureș, Târgu Mureș, Romania

Correspondence: Simona Muresan, MD, PhD, Associate Professor, University of Medicine and Pharmacy of Tîrgu Mureș, Physiology, CR Vivu, D9/19, Târgu Mureș, Mureș 540109 Romania;
dr_muremir@yahoo.com

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