Underlay Position Research Articles

Discussion of Elective Sonolucent Cranioplasty for Real-Time Ultrasound Monitoring of Flow and Patency of an Extra- to Intracranial Bypass.

Discussion of Elective Sonolucent Cranioplasty for Real-Time Ultrasound Monitoring of Flow and Patency of an Extra- to Intracranial Bypass.

A New Approach to an Old Technique—The S.U.T.R. First Technique

Ventral and incisional hernias of the abdominal wall are common problems treated by surgeons around the globe. Incisional hernias are common postoperative complications of abdominal laparotomies with a reported incidence of up to 20 per cent. The increasing use of prosthetic mesh in open ventral hernia repairs necessitated the development of different operative techniques used in the repairs. It also required that surgeons become facile with placement of the mesh in different anatomical positions on the abdominal wall. One of the most common locations is placement of the mesh in the underlay position. Many surgeons who use the underlay technique have expressed significant concerns. Among these are fear of an inadvertent bowel injury while placing the mesh, poor visualization during mesh placement, and the inability to use the underlay technique for difficult hernias. We present a very useful, if not, novel technique of open hernia repair using mesh in the underlay position that helps to 1) prevent complications, 2) facilitate easier mesh fixation, 3) simplify open repair of atypical ventral hernias, and 4) reduce total operative time while still adhering to the important fundamental principles of a tension-free hernia repair. This technique as we describe it has been compared with the old parachute technique, but we think this is a significant improvement of that seldom used technique. We believe the use of this technique for the underlay position makes open ventral hernia repair safer, faster, and easier; however, our goal for this article is to describe the procedure in detail. In addition, we recently have started using this technique to fix the mesh when doing the retrorectus approach as well.

Ventral Hernia Repair: A Meta-Analysis of Randomized Controlled Trials.

From the patient's perspective, a ventral hernia (VH) can cause pain, adversely affect function, increase size, cosmetically distort the abdomen, and incarcerate/strangulate abdominal contents. The only known "cure" for a VH is surgical repair. The aim of this study was to review systematically the published randomized controlled trials (RCTs) of the surgical care of VH. A search of the Ovid, MEDLINE, EMBASE, and Cochrane databases was performed to obtain reports of RCTs on the use of mesh reinforcement in abdominal wall hernia repair. The outcomes assessed were hernia recurrence and surgical site infection (SSI). The overall quality of evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). When feasible, based on assessment of heterogeneity, data were pooled and analyzed in a meta-analysis. Of the 10,349 titles screened, 25 articles (23 studies) met the search criteria. Evidence indicates that mesh reinforcement in clean cases can decrease hernia recurrence (number needed to treat = 7.9) but increase risk of SSI (number needed to harm = 27.8). Placing mesh in the sublay position (as opposed to the onlay or underlay position) may decrease the risk of hernia recurrence and SSI. Mesh reinforcement is recommended for all VH repairs in a clean case (high grade of evidence). Sublay mesh location may result in fewer recurrences and SSIs than onlay or inlay placement, but further study is needed to confirm this hypothesis (moderate grade of evidence).

Standard of Open Surgical Repair of Suprapubic Incisional Hernias.

Suprapubic incisional hernias (SIH) are a rare wall defect, whose surgical management is challenging because of limited literature. The proximity of the hernia to bone, vascular, nerve, and urinary structures, and the absence of posterior rectus sheath in this location imply adequate technique of surgical repair. We aimed to describe a cohort of female patients operated on for SIH after gynecological surgery using a homogeneous surgical technique and to report surgical outcomes. The records of all consecutive patients operated on for SIH in a specialized surgical center between January 2009 and January 2015 were retrospectively reviewed. The same open technique was performed, i.e., using a mesh placed inferiorly in the preperitoneal space of Retzius, with large overlap, and fixed on the Cooper's ligaments, through the muscles superiorly and laterally with strong tension, in a sublay or underlay position. The cohort included 71 female patients. SIH were recurrent in 31% of patients and was related to cesarean in 32 patients (45.1%) and to gynecologic surgery in 39 patients (54.9%). The mesh was totally extraperitoneal in 76.1% of patients. The postoperative mortality rate was null. The rate of specific surgical complications was 29.6%. After a median follow-up of 30.3months, the recurrence rate was 7%. The open approach for SIH repair was safe and efficient. Due to the paucity of adequate scientific studies, this reproducible open method could help moving toward a standardization of SIH surgical management.

Sublay versus underlay in open ventral hernia repair

BackgroundThe ideal location for mesh placement in open ventral hernia repair (OVHR) remains under debate. Current trends lean toward underlay or sublay repair. We hypothesize that in patients undergoing OVHR, sublay versus underlay placement of mesh results in fewer surgical site infections (SSIs) and recurrences. Materials and methodsA multi-institution database of all OVHRs performed from 2010 to 2011 was accessed. Patients with mesh placed in the sublay or underlay position and at least 1 mo of follow-up were included. Primary outcome was SSI. Secondary outcome was hernia recurrence. Multivariate analysis was performed using logistic regression for SSI and Cox regression for recurrence. Subgroup analysis of elective, midline ventral incisional hernias was also performed. ResultsOf 447 patients, 139 (31.1%) had a sublay repair. The unadjusted analysis showed no difference in SSI and lower recurrence using sublay compared with underlay. On multivariate analysis, there was no difference in SSI using sublay compared with underlay (odds ratio 1.5, 95% confidence interval [CI] 0.8–2.8). Recurrence was less common with sublay (hazard ratio 0.4, 95% CI 0.2–0.8). On subgroup analysis of elective, midline incisional hernias only (n = 247), there were more SSIs with sublay compared with underlay repair (28.0% versus 15.1%, P = 0.018); however, there was no difference in major SSI (sublay 9.3% versus underlay 5.8%, P = 0.315). There were fewer recurrences using sublay repair compared with underlay repair (10.7% versus 25.0%, P = 0.010). ConclusionsIn this multi-center, risk-adjusted study, sublay repair was associated with fewer recurrences than underlay repair and no difference in SSI. Randomized controlled trials are warranted to validate these findings.

A Self-adaptive Algorithm for Topology Matching in Unstructured Peer-to-Peer Networks

Peer-to-peer networks are overlay networks that are constructed over underlay networks. These networks can be structured or unstructured. In these networks, peers choose their neighbors without considering underlay positions, and therefore, the resultant overlay network may have a large number of mismatched paths. In a mismatched path, a message may meet an underlay position several times, which causes redundant network traffic and end-to-end delay. In some of the topology matching algorithms called the heuristic algorithms, each peer uses a local search operator for gathering information about the neighbors of that peer located in its neighborhood radius. In these algorithms, each peer also uses a local operator for changing the connections among the peers. These matching algorithms suffer from two problems; neither the neighborhood radius nor the local operator can adapt themselves to the dynamicity of the network. In this paper, a topology matching algorithm that uses learning automata to adapt the neighborhood radius and an adaptation mechanism inspired from the Schelling segregation model to manage the execution of the local operator is proposed. To evaluate the proposed algorithm, computer simulations were conducted and then the results were compared with the results obtained for other existing algorithms. Simulation results have shown that the proposed algorithm outperforms the existing algorithms with respect to end-to-end delay and number of mismatched paths.

Management of Cerebrospinal Fluid Leaks According to Size. Our Experience

ObjectiveWe present our experience in the reconstruction of cerebrospinal fluid (CSF) leaks according to their size and location. Materials and methodsFifty-four patients who underwent advanced skull base surgery (large defects) and 62 patients with CSF leaks of different origin (small and medium-sized defects) were included. Large defects were reconstructed with a nasoseptal pedicled flap positioned on fat and fascia lata and lumbar drainage was used. In small and medium-sized leaks of other origin, intrathecal fluorescein 5% was applied previously to identify the defect. Fascia lata in an underlay position was used for reconstruction, which was then covered with mucoperiosteum from the turbinate. Perioperative antibiotics were administered for 5–7 days. Nasal packing was removed after 24–48h. ResultsThe most frequent aetiology for small and medium-sized defects was spontaneous (48.4%), followed by trauma (24.2%), iatrogenic (5%) and then others. The success rate was of 91% after the first surgery and 98% in large skull base defects and small/medium-sized respectively. After rescue surgery, the rate of closure achieved was 100%. The follow-up was 15.6±12.4 months for large defects and 75.3±51.3 months for small/medium-sized defects without recurrence. ConclusionsEndoscopic surgery for closure of any type of skull base defect is the gold standard approach. Defect size does not play a significant role in the success rate. Fascia lata and mucoperiosteum allow a reconstruction of small/medium-sized defects. For larger skull base defects, a combination of fat, fascia lata and nasoseptal pedicled flaps provides a successful reconstruction.

Manejo de las fístulas nasales de líquido cefalorraquídeo según su tamaño. Nuestra experiencia

ObjectiveWe present our experience in the reconstruction of cerebrospinal fluid (CSF) leaks according to their size and location. Material and methodsFifty-four patients who underwent advanced skull base surgery (large defects) and 62patients with CSF leaks of different origin (small and medium-sized defects) were included. Large defects were reconstructed with a nasoseptal pedicled flap positioned on fat and fascia lata and lumbar drainage was used. In small and medium-sized leaks of other origin, intrathecal fluorescein 5% was applied previously to identify the defect. Fascia lata in an underlay position was used for reconstruction, which was then covered with mucoperiosteum from the turbinate. Perioperative antibiotics were administered for 5-7 days. Nasal packing was removed after 24-48hours. ResultsThe most frequent aetiology for small and medium-sized defects was spontaneous (48.4%), followed by trauma (24.2%), iatrogenic (5%) and others. The success rate was of 91% after the first surgery and 98% in large skull base defects and small/medium-sized respectively. After rescue surgery, the rate of closure achieved was 100%. The follow-up was 15.6±12.4 months for large defects and 75.3±51.3 months for small/medium-sized defects without recurrence. ConclusionsEndoscopic surgery for closure of any type of skull base defect is the gold standard approach. Defect size does not play a significant role in the success rate. Fascia lata and mucoperiosteum allow a reconstruction of small/medium-sized defects. For larger skull base defects, a combination of fat, fascia lata and nasoseptal pedicled flaps provide a successful reconstruction.

Outcome in porcine acellular dermal matrix reinforcement of infected abdominal wall defects: a prospective study

Management of infected abdominal wall defects is a subject of debate, and the use of prosthetic mesh repair is not recommended due to the dramatic rate of mesh infection. The aim of this prospective study was to determine the recurrence rate and long-term outcomes of repairing infected abdominal wall defects using the Strattice porcine acellular dermal matrix reinforcement through a single-stage surgical approach. From August 2010 to May 2012, consecutive patients treated for infected abdominal wall defects using Strattice, a biologic prosthesis, were enrolled. All data were collected prospectively and all patients were followed for physical examination and CT scan evaluation. The primary outcome measure was the recurrence rate. Eighteen patients were enrolled and 14 were evaluable. Of these, eight patients had mesh infections and six had enterocutaneous fistulas. Median follow-up was 13 months (range, 3-22) and median length of hospitalization was 13 days (range, 4-56). The Strattice was placed in the intraperitoneal underlay position in 12 patients, and in the retro-rectus position for two. Post-operative complications included skin dehiscence (n = 3), wound infection (n = 2), skin necrosis (n = 1), and seroma (n = 2). At the end of follow-up, six patients (43 %) experienced abdominal wall defect recurrence. The utility of biologic prostheses to repair infected abdominal wall defects is controversial; however, currently, they remain the only alternative to a two-staged surgery. Prospective, randomized studies in larger populations of patients are necessary to fully determine the usefulness of biologic prostheses in this setting.

Analysis with Ultrasound of Different Surgical Meshes for Abdominal Hernia Repair: Experimental Study

Objective: To evaluate the ultrasound dampening effect of the different types of meshes abdominal surgery after implantation in Wistar rats. Method: We used two Wistar rats, assessed positions and different types of meshes. The animals were anesthetized prior to surgery to open the abdominal cavity for placement of the prosthesis. Divided into three stages, 1) analysis of the abdominal cavity with ultrasound and no mesh 2) onlay position (mesh placed anterior the abdominal muscles) 3) underlay (intraperitoneal) for the posterior muscular. The meshes were used polypropylene (PP), polyester (PE), polypropylene/poliglecaprone (PU), polytetrafluoroethylene condensate (MO), polyester/ collagen (PC) and polypropylene/polydioxanone/oxidized regenerated cellulose (PRO). The animals were euthanized after the procedure. Results: There was no need to exclude the animals. The initial assessment showed no areas of difficulty or ease that would harm the exam. In all analyzes there was no problem identifying the the skin and subcutaneous tissue. There was a statistically significant difference in the attenuation of the meshes in both the onlay position p<0.001. Underlay position there was a small improvement in the graduation, with PE median (min-max) of 3 (2-5), PP, PU with 2 (1-5) and PC 2 (2-5) followed by PRO mesh with 1 (2-5) and MO with 0 (0-5) with statistical significance at p=0.001. However there was no comparison to the same mesh in two positions on the all meshes. Conclusion: All types of meshes used in this study was independent of the position of the sound degree attenuation in ultrasound examination. The polyester mesh got to take a lower degree of attenuation compared with other meshes of the study. Is needed a new test to check the attenuation in the long term.

Early results on the use of biomaterials as adjuvant to abdominal wall closure following cytoreduction and hyperthermic intraperitoneal chemotherapy

BackgroundHyperthermic chemotherapy applies thermal energy to both abdominal wall as well as the intra-abdominal viscera. The combination of the hyperthemia, chemotherapy and cytoreductive surgery (CRS) is associated with a defined risk of abdominal wall and intestinal morbidity reported to be as high as 15%, respectively to date, no studies have evaluated the use of biomaterial mesh as adjuvant to abdominal wall closure in this group of patients. In the present report, we hypothesized that post HIPEC closure with a biomaterial can reduce abdominal wall morbidity after CRS and hyperthermic intraperitoneal chemotherapy.Materials and methodsAll patients treated with HIPEC in a tertiary care center over 12 months (2008-2009) period were included. Eight patients received cytoreductive surgery followed by HIPEC for 90 minutes using Mitomycin C (15 mg q 45 minutes × 2). Abdominal wall closure was performed using Surgisis (Cook Biotech.) mesh in an underlay position with 3 cm fascial overlap-closure. Operative time, hospital length of stay (LOS) as well as postoperative outcome with special attention to abdominal wall and bowel morbidity were assessed.ResultsEight patients, mean age 59.7 ys (36-80) were treated according to the above protocol. The primary pathology was appendiceal mucinous adenocarcinoma (n = 3) colorectal cancer (n = 3), and ovarian cancer (n = 2). Four patients (50%) presented initially with abdominal wall morbidity including incisional ventral hernia (n = 3) and excessive abdominal wall metastatic implants (n = 1). The mean peritoneal cancer index (PCI) was 8.75. Twenty eight CRS were performed (3.5 CRS/patient). The mean operating time was 6 hours. Seven patients had no abdominal wall or bowel morbidity, the mean LOS for these patients was 8 days. During the follow up period (mean 6.3 months), one patient required exploratory laparotomy 2 weeks after surgery and subsequently developed an incisional hernia and enterocutaneous fistula.ConclusionThe use of biomaterial mesh in concert with HIPEC enables the repair of concomitant abdominal wall hernia and facilitates abdominal wall closure following the liberal resection of abdominal wall tumors. Biomaterial mesh prevents evisceration on repeat laparotomy and resists infection in immunocompromised patients even when associated with bowel resection.