META Score: An International Consensus Scoring System on Mesh-Tissue Adhesions.

BACKGROUND: Currently, the lack of consensus on postoperative mesh-tissue adhesion scoring leads to incomparable scientific results. The aim of this study was to develop an adhesion score recognized by experts in the field of hernia surgery. METHODS: Authors of three or more previously published articles on both mesh-tissue adhesion scores and postoperative adhesions were marked as experts. They were queried on seven items using a modified Delphi method. The items concerned the utility of adhesion scoring models, the appropriateness of macroscopic and microscopic variables, the range and use of composite scores or subscores, adhesion-related complications and follow-up length. This study comprised two questionnaire-based rounds and one consensus meeting. RESULTS: The first round was completed by 23 experts (82%), the second round by 18 experts (64%). Of those 18 experts, ten were able to participate in the final consensus meeting and all approved the final proposal. From a total of 158 items, consensus was reached on 90 items. The amount of mesh surface covered with adhesions, tenacity and thickness of adhesions and organ involvement was concluded to be a minimal set of variables to be communicated separately in each future study on mesh adhesions. CONCLUSION: The MEsh Tissue Adhesion scoring system is the first consensus-based scoring system with a wide backing of renowned experts and can be used to assess mesh-related adhesions. By including this minimal set of variables in future research interstudy comparability and objectivity can be increased and eventually linked to clinically relevant outcomes.

In vivo characterisation of the inflammatory reaction following mesh implantation in transgenic mice models.

INTRODUCTION: Hernia repair with prosthetic meshes represents one of the most common surgical procedures in the field of surgery. This intervention is always associated with an ensuing inflammatory response, angiogenesis and fibrotic encapsulation forming a foreign body granuloma (FBG) around the mesh fibres. Several studies have described this inflammatory reaction by characterising inflammatory cell infiltrate around the FBG after mesh explantation. However, very little is known about the real-time progression of such an inflammatory response. The aim of this study was to investigate the feasibility of monitoring the ongoing inflammatory response to mesh implantation using bioluminescence in vivo. MATERIALS AND METHODS: Three luciferase transgenic mice strains (FVB/N-Tg(Vegfr2-luc)-Xen, BALB/C-Tg(NFκB-RE-luc)-Xen and Tg(INS/EpRE-Luc)T20Rbl) were used. Mice were anaesthetized with 2 % isoflurane, and two incisions were made on the left and right sides of the abdomen of the mice. A 1-cm(2) propylene mesh was implanted subcutaneously in the right incision wound of each mouse, and the left wound served as control. Two hundred microliters of D-luciferin was injected into the mice, and bioluminescence measurements were done prior to the surgical intervention and subsequently every 3 days. After mesh explantation, histological analysis was done. Statistical analysis was done using prism GraphPad software. RESULTS: Bioluminescence results revealed different time points of maximum signal for the different mice strains. VEGFR2 gene expression peaked on day 6, NFkB on day 12 and ARE on day 3 post mesh implantation. We also observed much higher bioluminescent signal around the FBG surrounding the mesh as compared to the control wound, with p < 0.05 for all the different mice strains. CONCLUSION: Our results prove the possibility of monitoring the inflammatory reaction after mesh implantation in vivo using bioluminescence signal release. This provides a novel method of accessing and accurately describing the ongoing inflammatory response over a given period of time.

Characterization of innate and adaptive immune cells involved in the foreign body reaction to polypropylene meshes in the human abdomen.

BACKGROUND: Polypropylene (PP) mesh is widely used to reinforce tissues. The foreign body reaction (FBR) to the implant is dominated by innate immune cells, especially macrophages. However, considerable numbers of adaptive immune cells, namely T cells, have also been regularly observed, which appear to play a crucial role in the long-term host response. METHODS: This study investigated the FBR to seven human PP meshes, which were removed from the abdomen for recurrence after a median of one year. Using immunofluorescence microscopy, the FBR was examined for various innate (CD11b+ myeloid, CD68+ macrophages, CD56+ NK) and adaptive immune cells (CD3+ T, CD4+ T-helper, CD8+ cytotoxic, FoxP3+ T-regulatory, CD20+ B) as well as "conventional" immune cells (defined as cells expressing their specific immune cell marker without co-expressing CD68). RESULTS: T-helper cells (19%) and regulatory T-cells (25%) were present at comparable rates to macrophages, and clustered significantly toward the mesh fibers. For all cell types the lowest proportions of "conventional" cells (< 60%) were observed at the mesh-tissue interface, but increased considerably at about 50-100 µm, indicating reduced stimulation with rising distance to the mesh fibers. CONCLUSION: Both innate and adaptive immune cells participate in the chronic FBR to PP meshes with T cells and macrophages being the predominant cell types, respectively. In concordance with the previous data, many cells presented a "hybrid" pattern near the mesh fibers. The complexity of the immune reaction seen within the foreign body granuloma may explain why approaches focusing on specific cell types have not been very successful in reducing the chronic FBR.

Meloxicam, a COX-2 inhibitor, ameliorates ischemia/reperfusion injury in non-heart-beating donor livers.

BACKGROUND/AIMS: Chronic organ donor shortage has led to the consideration to expand the donor pool with livers from non-heart-beating donors (NHBD), although a higher risk of graft dys- or nonfunction is associated with these livers. We examined the effects of selective cyclooxygenase-2 (COX-2) inhibition on hepatic warm ischemia (WI) reperfusion (I/R) injury of NHBD. METHODS: Male Wistar rats were used as donors and meloxicam (5 mg/kg body weight) was administered into the preservation solution. Livers were excised after 60 min of WI in situ, flushed and preserved for 24 h at 4°C. Reperfusion was carried out in vitro at a constant flow for 45 min. During reperfusion (5, 15, 30 and 45 min), enzyme release of alanine aminotransferase and glutamate lactate dehydrogenase were measured as well as portal venous pressure, bile production and oxygen consumption. The production of malondialdehyde was quantified and TUNEL staining was performed. Quantitative PCR analyzed COX-2 mRNA. COX-2 immunohistochemistry and TxB(2) detection completed the measurements. RESULTS: Meloxicam treatment led to better functional recovery concerning liver enzyme release, vascular resistance and metabolic activity over time in all animals. Oxidative stress and apoptosis were considerably reduced. CONCLUSION: Cold storage using meloxicam resulted in significantly better integrity and function of livers retrieved from NHBD. Selective COX-2 inhibition is a new therapeutic approach achieving improved preservation of grafts from NHBD.

Comet-tail-like inflammatory infiltrate to polymer filaments develops in tension-free conditions.

BACKGROUND: Mesh reinforcement in hiatal hernia repair becomes more frequent but is charged by complications such as erosion or stenosis of the oesophagus. These complications are accompanied by an intense inflammatory infiltrate around the polymer fibres. To characterize this effect, the response to polypropylene fibres in the absence of tension was examined. METHODS: In rats, polypropylene sutures (USP size 1, 3-0 and 7-0) were placed in the subcutis of the abdominal wall without knot or tension. On postoperative days 3, 7 and 21, specimens were excised. The expressions of c-myc, ß-catenin, Notch3, COX-2, CD68 and Ki-67 were measured by immunohistochemistry. RESULTS: In the absence of tension, sutures were surrounded by a foreign body granuloma with an inflammatory infiltrate not encircling the fibre but forming almost symmetric comet-tail-like infiltrates on opposite sides. The expression of c-myc, ß-catenin, Notch3, COX-2, CD68 and Ki-67 was significantly reduced over time in the comet tail, but not in the granuloma. CONCLUSIONS: Even in tension-free conditions, surgical sutures cause a foreign body response with infiltrates of inflammatory cells. This reaction is shaped like a comet tail, and its extension depends on the diameter of the used fibre. Therefore, for reduction of perifilamental infiltrates, not only absence of tension is required, but also a small-sized fibre textile.

Treatment algorithm for postoperative upper gastrointestinal fistulas and leaks using combined vicryl plug and fibrin glue.

The incidence of clinically significant anastomotic leaks after upper gastrointestinal surgery is approximately 4 % - 20 %, and the associated mortality can be as high as 80 %. Depending on the clinical presentation, the treatment options are surgery, conservative treatment with external drainage, or endoscopic treatment. This report presents 39 cases of clinically apparent anastomotic leaks or fistulas after surgery for upper gastrointestinal cancers that were treated by endoscopy with insertion of fibrin glue alone (n = 24) or with a combination of Vicryl plug and fibrin glue (n = 15). Thirteen of the 15 patients who underwent Vicryl/fibrin treatments showed complete healing of the anastomotic leak or fistula after one to four sessions. Long-term follow-up results are presented. Postoperative upper gastrointestinal fistulas or anastomotic leaks can be managed successfully with low morbidity by means of endoscopic insertion of Vicryl mesh with fibrin glue, thereby avoiding repeated major surgery and its associated risks.

[The "ideal" mesh--more than a mosquito net]. / Das "ideale" Mesh - mehr als ein Mosquitonetz.

Modern meshes permit a radical treatment of hernias, an expectation that Billroth articulated already more than 100 years ago. Because clinical trials are insufficient to evaluate the distinct effects of modified mesh materials in regard to tissue biocompatibility and functionality, a basic understanding of the physico-chemical properties is essential for a rational selection of the most appropriate device. Experimental data indicate that particularly the mesh's porosity is of outstanding importance, resulting from the demanded tensile strength as well as the employed fibre material. Considering that different operation techniques require different mesh materials, specific requirements are discussed using the example of intraabdominal meshes, of parastomal meshes, of meshes in areas with bacterial contamination and of meshes in the hiatus region. Considering the late manifestation of some complications even after many years, any thorough quality control should include an assessment of explanted implant failures in addition to clinical experience.

Tissue remodeling macrophages morphologically dominate at the interface of polypropylene surgical meshes in the human abdomen.

BACKGROUND: Mesh implants are widely used to reinforce the abdominal wall, although the inevitable inflammatory foreign body reaction (FBR) at the interface leads to complications. Macrophages are suspected to regulate the subsequent scar formation, but it is still unclear whether adequate fibrous scar formation with collagen deposition depends mainly on the presence of M1 or M2 macrophages. METHODS: This study investigated the FBR to seven human polypropylene meshes, which were removed after a median incorporation time of 1 year due to the primary complaint of recurrence. Using immunofluorescence, the FBR was examined in six regional zones with increasing distance from the mesh fibers up to 350 µm, based on the cell densities, macrophage M1 (CD86) and M2 (CD163, CD206) phenotypes, deposition of collagen-I and -III, and expression of matrix metalloproteinase-2 (MMP-2) and -8 as indicator of collagen degradation. RESULTS: All mesh-tissue complexes demonstrated a decrease in cell density and macrophages with distance to the mesh fibers. Overall, about 60% of the macrophages presented an M2 phenotype, whereas only 6% an M1 phenotype. Over 70% of macrophages showed co-expression with collagen-I or -III and over 50% with MMP-2. CONCLUSIONS: The chronic FBR to polypropylene meshes is associated with an M2 macrophage response, which is accompanied by collagen deposition and MMP-2 expression. These findings challenge the idea that mainly M1 macrophages are related to inflammation and highlights that iatrogenic attempts to polarize these cells towards the M2 phenotype may not be a solution to ameliorate the long-term foreign body reaction.

The Gist of literature on pediatric GIST: review of clinical presentation.

AIM/BACKGROUND: To provide a review of existing literature on pediatric GIST with focus on clinical presentation. METHODS: A MEDLINE search was conducted in July 2007 to give an overview on literature concerning pediatric gastrointestinal stromal tumors (GISTs) with a focus on clinical presentation, using keywords "gastrointestinal stromal tumor" and one of the following "young/boy/girl/child/children/pediatric." Two of the authors sorted the resulting abstracts by relevance for a review on clinical aspects of pediatric GIST if they were in English language, not explicitly only reporting of adults and describing clinical features of patients. RESULTS: One hundred and six articles were found, 43 of which were excluded because they did not match the criteria mentioned above. We found 97 patients in the articles meeting our criteria, of which 38 cases had to be excluded, because of lacking clinical data, negative staining for CD117 or syndromal occurrence. This left 59 patients for analysis of clinical symptoms in the presentation of nonsyndromal CD117-positive GIST in children. DISCUSSION: Clinical feature most frequent was anemia in 86.4% (n=51) symptomatic either through acute or subacute bleeding. There was no palpable tumor in 88.1% (n=52), no abdominal pain in 84.7% (n=50), and no vomiting in 88.1% (n=52). Girls tend to show more high-grade tumors and existing case reports show a 2.7-fold higher incidence in females. Altogether epithelioid cell tumors are most frequent, although in boys spindle-cell tumors are reported more often. On the basis of National Institute of Health criteria (6) tumors were low grade in 22% (n=13), medium grade in 37.3% (n=22), and high grade in 35.6% (n=21). There were more high-grade tumors in girls than in boys (40.5% vs. 28.6%). Local excision was the operation most often performed, but details of surgery were missing in most cases. CONCLUSIONS: Pediatric GIST is a rare but considerable diagnosis in chronic anemia, which is the most frequent clinical finding with this tumor entity. Recent review articles focus on histopathologic criteria but omit clinical features and course of disease. In nonsyndromal CD117-positive GIST, girls tend to show more high-grade tumors and existing literature on pediatric GIST shows a 2.7-fold higher incidence in females. Altogether epithelioid cell tumors are most frequent, although in boys spindle-cell tumors are reported more often. Together with known differences in molecular changes and local as well as systemic tumor behavior this strongly suggests that pediatric GIST represents a different entity than adult GIST. After establishment of clear-cut pathologic features in the past, reports on preoperative diagnostic findings, long-term follow-up, and therapy have to be emphasized to clarify the relationship of these entities.

[Risk factors for anastomotic leakage after colorectal surgery]. / Risikofaktoren für das Auftreten postoperativer Anastomoseninsuffizienzen nach kolorektalen Resektionen.

BACKGROUND: Despite improved surgical techniques, anastomotic leakage is still a serious complication in colorectal surgery, resulting in increased morbidity and mortality. This study was initiated to investigate those clinical risk factors which may influence the onset of anastomotic wound-healing complications. METHODS: The postoperative courses were assessed in 400 consecutive patients who underwent colonic or rectal resection. Possible clinical risk factors were investigated by unvariate and multivariate analysis. RESULTS: 23 patients developed an anastomotic leakage (5.8 %). 10 patients could be treated conservatively, 13 had a second operation. In the multivariate analysis significant risk factors were perioperative radiotherapy (OR = 3.76 [95 % CI 1.03-13.7]), blood transfusion (OR = 2.98 [95 % CI 1.18-7.54]), alcohol consumption (OR = 2.94 [95 % CI 1.06-8.17]), and steroid medication (OR = 3.91 [95 % CI 1.17-13.07]). CONCLUSION: The clinically most important risk factors for leakage were radiotherapy and blood transfusion. Further analyses with a focus on the extracellular matrix, including other clinical factors may be valuable in identifying targets for improvement.

Elastic TPU Mesh as Abdominal Wall Inlay Significantly Reduces Defect Size in a Minipig Model.

Background: The open abdomen with mesh implantation, followed by early reoperation with fascial closure, is a modern surgical approach in difficult clinical situations such as severe abdominal sepsis. As early fascial closure is not possible in many cases, mesh-mediated fascial traction is helpful for conditioning of a minimized ventral hernia after open abdomen. The aim of this study was to evaluate the clinical utilization of an innovative elastic thermoplastic polyurethane mesh (TPU) as an abdominal wall inlay in a minipig model. Methods: Ten minipigs were divided in two groups, either receiving an elastic TPU mesh or a nonelastic polyvinylidene fluoride (PVDF) mesh in inlay position of the abdominal wall. After 8 weeks, mesh expansion and abdominal wall defect size were measured. Finally, pigs were euthanized and abdominal walls were explanted for histological and immunohistochemical assessment. Results: Eight weeks after abdominal wall replacement, transversal diameter of the fascial defect in the TPU group was significantly smaller than in the PVDF group (4.5 cm vs. 7.4 cm; p = 0.047). Immunhistochemical analysis showed increased Ki67 positive cells (p = 0.003) and a higher number of apoptotic cells (p = 0.047) after abdominal wall replacement with a TPU mesh. Collagen type I/III ratio was increased in the PVDF group (p = 0.011). Conclusion: Implantation of an elastic TPU mesh as abdominal wall inlay is a promising approach to reduce the size of the ventral hernia after open abdomen by mesh-mediated traction. However, this effect was associated with a slightly increased foreign body reaction in comparison to the nonelastic PVDF.

Biomechanical analyses of mesh fixation in TAPP and TEP hernia repair.

BACKGROUND: Reliable laparoscopic fixation of meshes prior to their fibrous incorporation is intended to minimize recurrences following transabdominal preperitoneal hernia repair (TAPP) and totally extraperitoneal repair (TEP) repair of inguinal hernias. However, suture-, tack- and staple-based fixation systems are associated with postoperative chronic inguinal pain. Initial fixation with fibrin sealant offers an atraumatic alternative, but there is little data demonstrating directly whether fibrin-based mesh adhesion provides adequate biomechanical stability for repair of inguinal hernia by TAPP and TEP. METHODS: Using a newly developed, standardized simulation model for abdominal wall hernias, sublay repairs were performed with six different types of commercially available hernia mesh. The biomechanical stability achieved, and the protection afforded by the mesh-hernia overlap, were compared for three different techniques: nonfixation, point-by-point suture fixation, and fibrin sealant fixation. RESULTS: Mesh dislocation from the repaired hernia defect was consistently seen with nonfixation. This was reliably prevented with all six mesh types when fixed using either sutures or fibrin sealant. The highest stress resistance across the whole abdominal wall was found following superficial fixation with fibrin sealant across the mesh types. There was a highly statistically significant improvement in fixation stability with fibrin sealant versus fixation using eight single sutures (p = 0.008), as assessed by the range of achievable peak pressure stress up to 200 mmHg. CONCLUSIONS: To ensure long-term freedom from recurrence, intraoperative mesh-hernia overlap must be retained. This can be achieved with fibrin sealant up to the incorporation of the mesh - without trauma and with biomechanical stability.

Gas-related impact of pneumoperitoneum on systemic wound healing.

INTRODUCTION: The aim of the present study was to investigate the gas-dependent effects of pneumoperitoneum on wound healing distant from the abdomen. MATERIALS AND METHODS: Dorsal skin incisions were performed in 54 male Sprague-Dawley rats. A CO(2) or a helium pneumoperitoneum of 3 mmHg was maintained before, with an overall duration of 30 min (each n = 18). Rats in the control group received laparotomy only (n = 18). Animals were killed after 5 and 10 days. The infiltration of macrophages (CD 68), expression of matrix metalloproteinase 13 (MMP-13) and collagen I/III ratios were analysed in the dorsal skin wounds. RESULTS: Both after 5 and 10 days, infiltration of macrophages and expression of MMP-13 were greatest after helium pneumoperitoneum. After 5 days, collagen I/III ratio was significantly increased in the helium group. After 10 days, collagen I/III ratio was lowest in the CO(2) group. CONCLUSION: Our results suggest beneficial effects on systemic wound healing for helium pneumoperitoneum as compared to CO(2).

Analysis of c-myc, PAI-1 and uPAR in patients with incisional hernias.

BACKGROUND: Disturbed wound healing leading to alterations in collagen composition has been thought to play a key role in the pathogenesis of incisional hernia formation. The aim of the present study was to further characterise the scarring process in such patients. METHODS: Mature skin scars from patients with either primary or recurrent incisional hernias were compared to mature abdominal skin scars from patients without hernias. The distribution of collagen types I and III was analysed using crosspolarisation microscopy. Expression of c-myc--a parameter for cell differentiation and proliferation--and of PAI-1 and uPAR--parameters of the proteolytic cascade in wound healing--were determined by immunohistochemistry. RESULTS: In agreement with previous studies, decreased collagen I/III ratios were found in patients with incisional hernias. In these patients, c-myc levels were significantly elevated whereas plasminogen activator inhibitor-1 (PAI-1) and urokinase-plasminogen activator receptor (uPAR) levels were only slightly increased. In contrast to controls, a significant correlation between c-myc, PAI-1 and uPAR expression and collagen I/III ratios was found in patients with incisional hernias. CONCLUSION: The differential correlation of collagen types and expression of c-myc, PAI-1 and uPAR within the scar tissue might represent a causal factor in incisional hernia formation.

MRI Evaluation of an Elastic TPU Mesh under Pneumoperitoneum in IPOM Position in a Porcine Model.

BACKGROUND: The frequency of laparoscopic approaches increased in hernia surgery over the past years. After mesh placement in IPOM position, the real extent of the meshes configurational changes after termination of pneumoperitoneum is still largely unknown. To prevent a later mesh folding it might be useful to place the mesh while it is kept under tension. Conventionally used meshes may lose their Effective Porosity under these conditions due to poor elastic properties. The aim of this study was to evaluate a newly developed elastic thermoplastic polyurethane (TPU) containing mesh that retains its Effective Porosity under mechanical strain in IPOM position in a porcine model. It was visualized under pneumoperitoneum using MRI in comparison to polyvinylidenefluoride (PVDF) meshes with similar structure. METHODS: In each of ten minipigs, a mesh (TPU containing or native PVDF, 10 × 20 cm) was randomly placed in IPOM position at the center of the abdominal wall. After 8 weeks, six pigs underwent MRI evaluation with and without pneumoperitoneum to assess the visibility and elasticity of the mesh. Finally, pigs were euthanized and abdominal walls were explanted for histological and immunohistochemical assessment. The degree of adhesion formation was documented. RESULTS: Laparoscopic implantation of elastic TPU meshes in IPOM position was feasible and safe in a minipig model. Mesh position could be precisely visualized and assessed with and without pneumoperitoneum using MRI after 8 weeks. Elastic TPU meshes showed a significantly higher surface increase under pneumoperitoneum in comparison to PVDF. Immunohistochemically, the amount of CD45-positive cells was significantly lower and the Collagen I/III ratio was significantly higher in TPU meshes after 8 weeks. There were no differences regarding adhesion formation between study groups. CONCLUSIONS: The TPU mesh preserves its elastic properties in IPOM position in a porcine model after 8 weeks. Immunohistochemistry indicates superior biocompatibility regarding CD45-positive cells and Collagen I/III ratio in comparison to PVDF meshes with a similar structure.

Fibrin sealant for mesh fixation in Lichtenstein repair: biomechanical analysis of different techniques.

BACKGROUND: Mesh fixation using sealants is becoming increasingly popular in hernia surgery. Fibrin sealant is an atraumatic alternative to suture or stapler fixation and is currently the most frequently used sealant. There are currently no biomechanical data available for evaluation of the quality of adhesion achieved with fibrin sealant during Lichtenstein hernia repair. METHODS: Five different suture and sealant techniques were evaluated and compared during simulated Lichtenstein hernia repair in an established, standardised biomechanical model for abdominal wall hernias. RESULTS: Significantly greater stability was achieved with fibrin sealant fixation of meshes than with point-by-point suture fixation. Fibrin adhesion protected meshes from dislocation at least as well as suture fixation with additional running-suture closure of the hernia orifice. Fibrin mesh fixation combined with additional support from running-suture hernia closure was significantly (P < or = 0.002) superior to all other methods. CONCLUSIONS: On the basis of these favourable biomechanical properties, mesh fixation using fibrin sealant can be recommended for use in onlay repair of transinguinal hernias.

Risk-adjusted procedure tailoring leads to uniformly low complication rates in ventral and incisional hernia repair: a propensity score analysis and internal validation of classification criteria.

BACKGROUND: The usual approach in hernia surgery is to select the ideal repair method independent of the patient's characteristics. In the present study, we change the approach to ask which technique is best for the individual patient`s risk profile. For this, two criteria are important: does the patient need reconstruction of the abdominal wall? or does he or she need treatment of symptoms without being exposed to unnecessarily high perioperative risks? METHODS: In a heuristic selection procedure, 486 consecutive patients were classified according to their characteristics as low-risk or high-risk for postoperative complications. Low-risk patients preferentially underwent open abdominal wall reconstruction with mesh (MFR + mesh), high-risk patients mainly a bridging-mesh procedure, either by laparoscopic (Lap.-IPOM) or open approach (Open-IPOM). Primary outcome was the incidence of postoperative complications. Secondary outcome was the recurrence-free interval. The propensity score was used for covariate adjustment analyzing recurrence rate as well as postoperative complications using Cox regression and logistic regression, respectively. RESULTS: Comparison of all surgical procedures showed risk factors had no independent influence on occurrence of complications (p = 0.110). Hernial gap width was an independent factor for occurrence of complications (p = 0.002). Propensity score adjustment revealed Lap.-IPOM to have a significantly higher recurrence rate than MFR + mesh (HR 2.367, 95% CI 1.123-4.957, p = 0.024). Three or more risk factors were protective against recurrence (HR 0.454, 95% CI 0.221-0.924, p = 0.030). In the univariate Cox regression analysis for recurrence, age >50 years was a protective prognostic factor (HR 0.412, 95% CI 0.245-0.702, p = 0.002). CONCLUSIONS: The classification criteria applied were internally validated. The heuristic algorithm ensured that patients at high-risk of complications did not have a higher perioperative complication rate than patients at low-risk.

Improved abdominal wall wound healing by helium pneumoperitoneum.

BACKGROUND: Despite widespread use of the endoscopic technique in the treatment of inguinal and incisional hernias, knowledge about its impact on abdominal wall wound healing is rare. Questions remain regarding the risk of port-site hernias and hernia recurrence. The current study investigated the gas-dependent effects of pneumoperitoneum on laparotomy wound healing. METHODS: Laparotomy was performed in 54 male Sprague-Dawley rats. A carbon dioxide (n = 18) or helium (n = 18) pneumoperitoneum of 3 mmHg was maintained before and after laparotomy, with an overall duration of 30 min. The rats in the control group (n = 18) received no pneumoperitoneum. The animals were killed after 5 and 10 days, and the abdominal wall was explanted for subsequent histopathologic examinations of the laparotomy wound. The granuloma formation in hematoxylin and eosin-stained sections was analyzed. Infiltration of macrophages (CD68) and expression of matrix metalloproteinases (MMP-8 and MMP-13) were examined by immunohistochemistry. The collagen type 1 to type 3 ratio was investigated by cross-polarization microscopy after Sirius Red staining. RESULTS: After 5 and 10 days, the percentages of CD68-positive cells, granuloma formation, and expression of MMP-8 did not differ between the groups. In contrast, after both 5 and 10 days, the expression of MMP-13 and the collagen 1 to 3 ratio were significantly higher after helium pneumoperitoneum than in the control animals. CONCLUSION: The results suggest that helium pneumoperitoneum may ameliorate wound healing within the abdominal wall and could therefore represent a beneficial gas for endoscopic hernia repair.