One year experience of swine dermal non-crosslinked collagen prostheses for abdominal wall repairs in elective and emergency surgery

Incisional hernia remains a common complication in abdominal surgery and occurs after elective laparotomy with an incidence from 2 to 20 % or more [7, 19, 20]. However, these rates can increase (as high as 50 %) after abdominal closure in emergency surgery and in the abdominal repair following OA procedure [21‐23]. The approach to the abdominal wall surgical repair is dramatically changed in the last years due to the availability of new repair materials, like biologic prostheses. Although in last years many studies tried to find an agreement about specific technique and materials that should be applied to repair of complex ventral hernia, at present, no strong consensus has been found yet [4, 24]. However the use of biologic prostheses is actually accepted by the medical community for addressing abdominal wall defects, particularly in contaminated and potentially contaminated fields [11, 25]. Despite this, the numerous advantages of biologic materials have been proven [11, 26, 27].

The present study reports a one-year experience about the usage of biological prostheses in different fields from elective surgery to emergency surgery and OA procedure. We analyze our surgical indications to the usage of biological meshes to evaluate the outcomes and the feasibility in these fields.

In the first group we considered only the patients underwent to ventral hernia repair in elective surgery. In all patients the abdominal wall defect was associated with high risk of contamination or an already existing infection imposed the positioning of a biological prostheses. The decision of the positioning of the prosthesis was based on the VHWG and the Italian Biological Prostheses work-group recommendations [4, 11], according to the degree of contamination potential or effective, and according to co-morbidities of the patient. In literature also others studies confirmed and supported these recommendations [7, 28, 29]. In our study, more than half of the patients of this group had more than one comorbidity (in particular immunosuppression and malignancy), that associated with a local wound infection or intra-abdominal infection have prevented the use of a synthetic mesh. In two third of patients the mesh was placed in the retromuscolar space, in line with the literature [9, 30]. The “sublay” position (posterior to the rectus muscle) has been the most used, in fact it allows for better tissue incorporation and lower chance of bacterial contamination, increases neo-angiogenesis and avoids the direct contact with intra-abdominal viscera [1, 9]. In this group only one patient died at three months for a septic shock, and in one case we had to remove the mesh because the patient was re-operated for an intestinal ischemia.

At the analysis of the second group (patients underwent to ventral hernia repair in emergency conditions) we found that the presence of wound infection or intra-abdominal infection are the main indication requiring a biological mesh positioning. This decision was also dictated by the important comorbidities present in half of patients. The other important point has been the age of patients (older than patients in others group, with a median age of 75.5 years). In last year the number of elderly patients (>65 years) underwent to ventral hernia repair in emergency setting is increasing [2]. A recent study reports that the risk of operative factors associated with the risk of surgical site infection were open procedures, incisional/ventral repairs, and hernia repairs with bowel obstruction/necrosis [2]. Into account of these data and according to the VHWG recommendations [4] we decided to repair the abdominal wall defect with a biological mesh, with favorable outcomes and with an acceptable hospital stay (median 16.5 days).

The third group was the largest group. The problem of abdomen closure after OA procedure remains the most critical point for these patients [21‐23]. Data about long-terms outcome after repair of abdominal wall in OA procedure are still lacking and the durability of the different biologic meshes has not been clinically proved [26, 31]. Our surgical indications for an OA procedure requiring a biological prostheses positioning were the difficulty to close the abdominal wall (the anterior and the posterior fascia) or to reinforce the closure of the posterior fascia (when the anterior fascia was impossible to close). The main causes for a laparostomy were secondary peritonitis, intestinal ischemia and trauma. The conditions that required leaving the abdomen open remains the abdominal compartment syndrome (ACS) or the conditions that promote an intra-abdominal hypertension (IAH) (intestinal ischemia, acute severe pancreatitis, vascular complications), or in case of damage control surgery (trauma) [13, 26, 32‐34]. Recently the approach to the intra-abdominal sepsis was changed and leaving the abdomen open in that condition has been proven to reduce mortality and post-operative complications [31, 35]. The primary goal remains the source control and a temporary abdominal closure was considered a valid instrument to manage severe abdominal sepsis [35]. In our series the traumatized patients undergone to OA had severe trauma (ISS > 25). In the two-third of cases we have proceed to OA management to prevent an ACS; in only one-third OA procedure was considered as treatment of the IAH or of the ACS. In patients with intra-abdominal sepsis the scoring system to estimate the severity and prognosis of secondary peritonitis we used was the MPI [15]. Literature reports that a MPI greater that 29 relates with high mortality rates (100 % vs 0–2.3 % in patients with MPI < 21) [15]. In our series one–third of patients have severe peritonitis (MPI > of 29), and these MPI values associated with the important comorbidities may be the responsible for the high peri-operative mortality rate (29.4 % at our analysis). In the present series the status of the OA has been evaluated at the first laparotomy and at the last one according to the Björck classification [18]. Data reported an increased number of patients presenting a Grade 1A (clean OA without adherence between bowel and abdominal wall or fixity) at the abdomen closure (from 41.4 %, at the first laparotomy, to 76.6 %, at the last laparotomy). These results showed the efficacy of the OA treatment in reducing the intra-abdominal contamination. Regarding to the technique used for temporary abdominal closure we used the NPWT in almost all cases. This strategy seems to be the best in preventing evisceration, actively remove any infected or toxic fluid from the peritoneal cavity, prevent the formation of entero-atmospheric fistulas, preserve the fascia and the abdominal wall domain, make reoperation easy and safe, and achieve early definitive closure [23, 26, 36]. Our goals were to close the abdomen wall as soon as possible (within 5–7 days) [26, 27, 37] to reduce the OA complications. A recent prospective controlled trial and a systematic review suggested that use of a dynamic fascial sutures combined with NPWT in the treatment of OA for intra-abdominal sepsis is safe and associated to a low rate of incisional hernias and entero-atmospheric fistula [22, 23]. However in our series almost all patients despite the NPWT alone, the closure of the abdominal wall happened in an average of 6.1 days, but in 53 % of cases the fascia was closed with a mesh in the retromuscolar space [9, 30]. The main complications after OA remain the enterocutenaous fistula and the long-term ventral hernia, in addition to the high rate of morbidity and mortality associated with the procedure [8, 26, 38]. A recent meta-analysis about OA and temporary abdominal closure techniques in non-trauma patients (4358 patients) reported a mortality rate near to 30 %, with an overall rate of fistula of 12.1 %, with a 14.6 % in series applying NPWT without fascial traction, and of 5.7 % after NPTW with fascial traction [38]. Others studies reported a high delayed facial closure rate ranging from 34 % and 73.6 % in septic patients, with lower rates in trauma patients due to the more frequent early abdominal closure [23]. In our study only one patient had a duodenal fistula and required the removal of the prostheses (being managed with a VAC therapy to control the spillage of duodenal contents [38]) and only one patient presented an incisional hernia without complications. These low rates of incisional hernia are probably due to the lack of a long-term follow-up. The other complications in present study were related wound infection or dehiscence that were managed with local wound dressing. Also in our data the rate of peri-operative mortality remains high (29.4 %), similar with the data find in the literature (30 %), however this is probably due to the extremely compromised conditions of the patients and the paucity of cases [2, 38].

Despite the limitations present study showed that the use of non-cross-linked porcine dermal meshes in different surgical setting, particularly in elderly and septic patients is safe and effective, without worsening morbidity and mortality.