An in vitro study assessing the infection risk of low-cost polyethylene mosquito net compared with commercial hernia prosthetics.

BACKGROUND: The innovative use of sterilized mosquito net as a cheaper alternative to commercial mesh for hernia repair has gained increasing recognition. Developing health care systems have inherently higher surgical site infection rates, and concerns regarding the introduction of untested prosthetic hernia meshes have been raised. This in vitro study assesses the infection risk of polyethylene (PE) mosquito net mesh compared with commercial hernia prosthetics by assessing the essential (first) step in the pathogenesis of mesh infections. MATERIALS AND METHODS: Individual meshes were inoculated with Staphylococcusepidermidis and Staphylococcusaureus with a bacterial inoculum of 10(2) bacteria. Inoculated meshes were incubated for 18 h in tryptone soy broth and then analyzed using scanning electron microcopy. The final fraction of the bacteria adherent to each of the meshes was compared. One-way analysis of variance was performed on the bacterial counts. The Tukey test was used to determine the difference between the different biomaterials in the event the one-way analysis of variance was significant. RESULTS: There was no significant difference in the mean number of adherent bacteria to PE mosquito net compared with the monofilament polypropylene-based meshes (Prolene and Bard Soft Mesh). Multifilament Vypro mesh had significantly greater mean bacterial adherence compared with PE mosquito net (P < 0.001 with S aureus and P = 0.003 with S epidermidis). CONCLUSIONS: In vitro infection risk of PE mosquito net is not significantly different from commonly used monofilament polypropylene commercial prosthetics and is in fact lower than a commonly used commercial multifilament mesh. This study adds to the growing body of evidence that indicates that these meshes can be safely deployed.

An experimental study exploring the relationship between the size of bacterial inoculum and bacterial adherence to prosthetic mesh.

BACKGROUND: Infection is a major concern with medical implants. Surgical meshes used for the repair of abdominal wall hernias are associated with wound infection rates ranging from 7 to 18 %. Although mesh infection is relatively rare, once a patient shows clinical signs of mesh infection, the surgeon may be required to remove the mesh, resulting in additional surgery, morbidity, and cost. The usual causative organisms associated with cases of mesh infection are Staphylococcus species. The first stage of implant infection is bacterial adherence to the biomaterial. An accurate assessment of adherent bacteria to medical prosthetics is therefore important in order to determine the infection risk associated with surgical implants. METHODS: This experimental study evaluated the relationship between the size of the bacterial inoculum and bacterial adherence to three commonly used hernia prosthetics (polypropylene, polyester, and ePTFE). Tenfold dilutions of S. epidermidis (Evans-ATCC 12228) and S. aureus (Rosenbach-ATCC 25923), created with phosphate-buffered saline, were used to inoculate each of the meshes in 3 ml of tryptone soya broth for 18 h at 37 °C, 95 % air/5 % CO(2). The number of viable bacteria in each dilution was calculated using a spot plate technique. The number of adherent bacteria to the meshes was counted using direct imaging analysis with scanning electron microscopy and expressed as a mean. RESULTS: One hundred eight mesh samples were analysed. The size of the bacterial inoculum of S. epidermidis significantly influenced the number of adherent bacteria to the mesh, and lower rates of adhesion were observed with smaller inoculums for all three meshes (polypropylene, p = 0.02; ePTFE p = 0.03; polyester p = 0.02). A similar, albeit less profound, pattern of results was observed with S. aureus. Bacterial adherence was observed with inoculum sizes as small as <10 bacteria. CONCLUSIONS: The results demonstrate that even a very low number of bacterial inoculums can result in adherence to hernia biomaterials and that the level of adherence is directly related to the size of the inoculum. These in vitro results provide evidence that the size of the inoculum is important in the colonization of hernia biomaterials and demonstrate the importance of minimising the bacterial inoculum in the clinical setting.

Mosquito net mesh for abdominal wall hernioplasty: a comparison of material characteristics with commercial prosthetics.

BACKGROUND: The use of sterilized mosquito net as a cheaper alternative to commercial mesh used in hernia repair has previously been published. However, as no standards with regard to the material have been documented, we aimed to define the characteristics of a commonly available and low-cost mosquito net, which has already been shown to be clinically efficacious in groin hernia repair. We compared its characteristics to other commercially available meshes, in keeping with the well-established FDA and MHRA regulatory processes. METHODS: The macromolecular structure of the mosquito net was determined by vibrational spectroscopy. The ultrastructure of the meshes was examined with scanning electron microscopy, and uniaxial and burst tensile strength testing was performed. The following parameters were assessed: polymer type, filament characteristics, pore size, weight, linear density, elasticity, and tensile strength. RESULTS: The mosquito net was a polyethylene homopolymer, knitted from monofilament fibers with a mean filament diameter of 109.7 µm and a mean mesh thickness of 480 µm. The mean pore maximum diameter was 1.9 mm, with 91.2 % porosity, 53.7 g/m(2) mean mesh weight, and a linear mass density of 152 denier. This was comparable to the "large pore" (class I) commercial meshes. The bursting force for polyethylene mosquito net was greater than for UltraPro and Vypro (43.0 vs. 35.5 and 27.2 N/cm, respectively), and the mosquito net exhibited less anisotropy compared to the commercial meshes. CONCLUSIONS: The material and mechanical properties of the polyethylene mosquito net are substantially equivalent to those of commonly used lightweight commercial meshes.

Cost-effectiveness of inguinal hernia surgery in northwestern Ecuador.

BACKGROUND: Cost-effectiveness of tension-free inguinal hernia repair at a private 20-bed rural hospital in Esmeraldas Province, Ecuador, was calculated relative to no treatment. METHODS: Lichtenstein repair using mosquito net or polypropylene commercial mesh was provided to patients with inguinal hernia by surgeons from Europe and North America. Prospective data were collected from provider, patient, and societal perspectives, with component costs collected on site and from local supply companies or published literature. Patient outcomes were forecasted using disability adjusted life years (DALYs) averted. Uncertainty in patient-level data was evaluated with Monte-Carlo simulation. RESULTS: Surgery was provided to 102 patients with inguinal hernias of various sizes. Local anesthesia was used for 80 % of operations during the first mission, and spinal anesthesia was used for 89 % in the second mission. Few complications were observed. An average 6.39 DALYs (3,0) were averted per patient (95 % confidence interval: 6.22-6.84). The average cost per patient was US$499.33 (95 % CI: US$490.19-$526.03) from a provider perspective, US$118.79 (95 % CI: US$110.28-$143.72) from a patient perspective, and US$615.46 (95 % CI: US$603.39-$650.40) from a societal perspective. Mean cost-effectiveness from a provider perspective was US$78.18/DALY averted (95 % CI: US$75.86-$85.78) according to DALYs (3,0) averted using the West Life Table level 26, well below the Ecuadorian per-capita Gross National Income (US$3,850). Results were robust to all sensitivity analyses. CONCLUSIONS: Inguinal hernia repair was cost-effective in western Ecuador through international collaboration.

Guidelines for surgeons on establishing projects in low-income countries.

BACKGROUND: There is increasing interest by surgeons in high-income countries to support colleagues in low-income countries to improve the provision of surgical care, particularly in rural areas. Such interest may be demonstrated by single individuals, short-term surgical missions, or establishment of partnerships. Such altruistic efforts may cause problems unless properly planned and carried out. METHODS: We reviewed the available literature and consulted widely to establish consensus guidelines for any surgeon considering participating in an initiative to improve surgical care in low-income countries. RESULTS: A series of recommendations is presented. These include ensuring that projects are appropriate, that there is an emphasis on training local healthcare providers in all aspects of perioperative care, that outcomes are monitored, and that initiatives work with local and regional training programs. CONCLUSIONS: With adherence to these recommendations, we hope that future partnerships and missions can maximize their effectiveness and minimize the risks of potential harm done.

Safety and sterilization of mosquito net mesh for humanitarian inguinal hernioplasty.

BACKGROUND: Inguinal hernia repair is one of the most commonly performed operations in Africa. Prosthetic repair with commercially available mesh is generally considered too expensive in low-income countries. Elective groin hernia surgery with mosquito net mesh has recently been described. However, can mesh sterility in resource-poor countries be guaranteed to ensure both effectiveness and safety? METHODS: Copolymer and polyester mosquito net mesh were steam-sterilized at varying temperatures. PubMed and EMBASE were searched using key words, MeSH, and subject headings (mosquito net mesh, mesh sterilization, inguinal hernia repair). RESULTS: Copolymer mosquito net mesh manufactured in India can be safely sterilized at lower (less "strict") temperatures (121°C) than those usually demanded by advanced health care systems (134°C). The literature search revealed a number of case series but all with limited follow-up. Available data, however, support the use of this type mosquito net mesh in the elective repair of hernias. CONCLUSIONS: Hernia repair with mosquito net mesh is a plausible, safe, cost-effective alternative in low-income countries. Sterilization in steam autoclaves that have accurate temperature control is required.

Public health and policy issues of hernia surgery in Africa.

Inguinal hernia repair has been overlooked as a public health priority in Africa, with its high prevalence largely unrecognized, and traditional public health viewpoints assuming that not enough infrastructure, human resources, or financing capacity are available for effective service provision. Emerging evidence suggests that inguinal hernias in Ghana are approximately ten times as prevalent as in high-income countries, are much more long-standing and severe, and can be repaired with low-cost techniques using mosquito net mesh through international collaboration. Outcomes from surgery are comparable to published literature, and potential exists for scaling up capacity. Special attention must be paid to creating financing systems that encourage eventual local self-sustainability.

The SPINK1 N34S variant is associated with acute pancreatitis.

OBJECTIVE: Acute pancreatitis (AP) is a disease whose pathogenesis remains largely obscure. Genetic research has focussed attention upon the role of the pancreatic protease/protease inhibitor system. The aim of this study was to investigate the prevalence of genetic variants of the trypsin inhibitor, SPINK1, in acute pancreatitis. METHODS: We genotyped 468 patients with AP and 1117 healthy controls for SPINK1 alterations by single-strand conformation polymorphism analysis and by melting curve analysis using fluorescence resonance energy transfer probes. RESULTS: The c.101A>G (p.N34S) variant was detected in 24/936 alleles of patients and in 18/2234 alleles of healthy controls (odds ratio=3.240; 95% confidence interval: 1.766-5.945; P<0.001). In the UK patients, the mean age of patients with N34S was 11.9 years younger compared with N34S negative patients (P=0.023), but this was not apparent in the German patients. Allele frequencies for the c.163C>T (p.P55S) variant did not differ between patients and controls. CONCLUSION: The SPINK1 N34S variant is associated with acute pancreatitis. This supports the importance of premature protease activation in the pathogenesis of AP and suggests that mutated SPINK1 may predispose certain individuals to develop this disease.

Tumour necrosis factor microsatellite haplotypes are associated with chronic pancreatitis.

CONTEXT: Alcohol is the major aetiological agent for both chronic pancreatitis and alcoholic liver disease. However, as only a minority of alcoholics develop either chronic pancreatitis or alcoholic liver disease, there are clearly genetic or environmental cofactors that determine individual susceptibility to these diseases. OBJECTIVE: To determine whether polymorphisms of the TNF gene may account for individual susceptibility to develop chronic pancreatitis or alcoholic liver disease. DESIGN: A controlled study. PATIENTS: We analyzed 73 patients with chronic pancreatitis, 103 healthy controls, 39 patients with alcoholic liver disease and 29 alcoholics without liver or pancreatic disease. RESULTS: The intermediate/low TNF secreting haplotype a6b5c1d3e3 was over-represented in chronic pancreatitis compared to healthy controls (OR=2.08; 95% CI: 1.07-4.06); P=0.019) and in alcoholic chronic pancreatitis compared to healthy controls (OR=2.08; 95% CI: 1.01-4.29; P=0.029). The high TNF secreting haplotypes, a2b3c1d1e3 and a2b5c2d4e3 were under-represented in chronic pancreatitis compared to healthy controls (OR=0.48; 95% CI: 0.22-1.04; P= 0.043) and in alcoholic chronic pancreatitis compared to alcoholic controls (OR=0.20; 95% CI: 0.05-0.77; P=0.014), respectively. CONCLUSION: A reduced capacity to produce TNF may be responsible for the induction of chronic pancreatitis.

Heat shock factor-1 and nuclear factor-kappaB are systemically activated in human acute pancreatitis.

CONTEXT: Nuclear factor-kappa B (NF-kappaB) is a transcription factor for a wide range of proinflammatory mediators while heat shock factor-1 (HSF-1) transcribes stress proteins that protect against cellular damage. Both are attractive therapeutic targets, undergoing investigation in other acute inflammatory conditions, such as sepsis. OBJECTIVE: To evaluate the role of the transcription factors NF-kappaB and HSF-1 in human acute pancreatitis and their relationship to cytokine/chemokine production, disease severity and outcome. PATIENTS: Twenty-four patients with acute pancreatitis and 12 healthy controls. MAIN OUTCOME MEASURES: Peripheral blood mononuclear cells were isolated. NF-kappaB and HSF-1 were measured by electrophoretic mobility shift assay. Soluble tumor necrosis factor (TNF) receptor II and interleukin-8 were measured by ELISA. Acute physiology scores (APS), APACHE II scores and final Atlanta designations of severity were also determined. RESULTS: Systemic NF-kappaB activation occurs in acute pancreatitis compared to healthy controls (P=0.004). However, there was no significant difference between those with mild and severe disease (P=0.685). Systemic activation of HSF-1 was observed in acute pancreatitis compared to healthy controls although this did not reach statistical significance (P=0.053). Activation, however, was greatest in those who had a final Atlanta designation of mild pancreatitis compared to those who had a severe attack of acute pancreatitis (P=0.036). Furthermore, HSF-1 was inversely correlated with acute physiology score (APS; r=-0.49, P=0.019) and APACHE II score (r=-0.47, P=0.026). CONCLUSIONS: Both NF-kappaB and HSF-1 are systemically activated in human acute pancreatitis. HSF-1 activation may protect against severity of pancreatitis.

Cytochrome P450 2E1 high activity polymorphism in alcohol abuse and end-organ disease.

AIM: To investigate a possible role for a recently identified polymorphism in the gene of cytochrome P450 2E1, the presence of which is associated with high activity of the enzyme. METHODS: Two hundred and thirty-nine alcohol consumers, ICD 10.1/.2 (ALC), and 208 normal controls were studied. PCR amplification of the CYP2E1 gene region was performed to assess polymorphic variation. Fisher's exact test was used to assess the data. RESULTS: Twelve normal controls (5.8%) possessed the insertion. Five ALC (2.1%) had the insertion; of these 2 of 144 with alcohol induced chronic pancreatitis, none of 28 with alcoholic liver disease and 3 of 67 without end-organ disease had the polymorphism. A significantly Lower frequency of subjects possessed the insertion than normal controls [P=0.049 (genotype analysis P=0.03)]. To further assess, if there was a relationship to alcohol problems per se or end-organ disease, we compared patients with alcohol induced end-organ disease vs alcoholic controls without end-organ disease vs normal controls which again showed a significant difference [P=0.045 (genotype analysis, P=0.011)], further sub-group analysis did not identify which group(s) accounted for these differences. CONCLUSION: We have shown the frequencies of this high-activity polymorphism in alcohol related patient groups for the first time. The frequency is significantly less in alcoholics than normal controls, as with high activity polymorphisms of alcohol dehydrogenase. The biological significance, and whether the relevance is solely for alcoholism or is there a relationship to end-organ disease, would benefit from the assessment in the populations with a greater frequency of this polymorphism.

Dispositional pessimism predicts delayed return to normal activities after inguinal hernia operation.

BACKGROUND: The traditional outcome measure to assess effectiveness of inguinal hernia operation was recurrence. Open mesh repair has reduced recurrence rates and attention is now turning to outcomes other than recurrence. The factors influencing the large variation in reported times of resumption of normal activities after inguinal hernia repair are many and diverse. The human factors influencing resumption of normal activity are rarely reported. METHODS: We undertook a prospective study of 206 patients undergoing primary inguinal hernia repair in an ambulatory setting in a public hospital to ascertain whether dispositional outlook on life affected resumption of normal activity after hernia repair. Outlook on life was assessed using the life orientation test. An independent observer assessed the patients preoperatively and determined timing of resumption of normal activities. RESULTS: Regression analysis showed a highly significant relationship between delayed return to normal activity and dispositional pessimism (P =.0004). DISCUSSION: Dispositional pessimism correlates strongly with delayed return to normal activities. Further studies of this kind will help to elucidate the human factors that affect recovery after operation. Studies which use return to normal activities as a measure of the outcome of a surgical technique should include an assessment of the patient's preoperative outlook on life. Surgeons should consider the personality of the patient presenting for groin hernia repair and may wish to tailor their counseling accordingly.

Use of the Internet and information technology for surgeons and surgical research.

The recent, and extensive, expansion in the use of computers and the Internet offers great potential for benefit in surgical research and, increasingly, surgical practice. However, in addition to the usefulness of information technology, much time can be spent achieving little and the potential missed because of the complexity and excess of information available. In this article, we examine some useful areas relevant to surgeons and surgical research, such as Internet service provision and E-mail, databases, medical Websites, and potential future directions.

Autologous reconstruction of the inguinal ligament using pedicled fascia lata flap: A new technique.

INTRODUCTION: A technique of reconstructing the inguinal ligament using a pedicled fascia lata flap is described. PRESENTATION OF CASE: A 62-year-old man was referred with massive bilateral abdominal wall hernias, following numerous attempts at repair and subsequent recurrences. There was complete absence of the right inguinal ligament. The inguinal ligament was reconstructed using a strip of fascia lata, pedicled on the anterior superior iliac spine. This was transposed to cover the external iliac vessels, and sutured to the pubic tubercle. The musculoaponeurotic abdominal wall was reconstructed with two 20cm×20cm sheets of porcine acellular dermal matrix and an overlying sheet of polypropylene mesh, sutured to the remaining abdominal wall muscles laterally, and to both inguinal ligaments. The cutaneous abdominal wall was closed with an abdominoplasty technique. The reconstruction has remained intact nine months following surgery. DISCUSSION: Complete destruction of the inguinal ligament is rare but can occur following multiple operative procedures or trauma. To date, the only published reports of inguinal ligament reconstruction have been performed using synthetic mesh. The use of autologous tissue should reduce the risk of erosion into the neurovascular bundle, seroma formation, and enhance integration into surrounding tissues. CONCLUSION: This new technique for autologous reconstruction of the inguinal ligament provides a safe alternative to the use of synthetic mesh in the operative armamentarium of plastic and hernia surgeons.

Prosthetic mesh materials used in hernia surgery.

It is estimated that 20 million prosthetic meshes are implanted each year worldwide. It is clear that the evolution of meshes is not yet complete and the ideal mesh is yet to be found. There is a vast array of prosthetics available for hernia repair. This review outlines the properties of available meshes and the evidence to be considered when choosing a prosthetic for hernia repair.

Cost-effectiveness of groin hernia surgery in the Western Region of Ghana.

OBJECTIVE: To calculate the cost-effectiveness of tension-free inguinal hernia repair with mosquito net mesh in the Western Region of Ghana. DESIGN: Prospective study. SETTING: Four district hospitals in the Western Region of Ghana. PATIENTS: A total of 113 referred or presenting patients from rural areas with inguinal hernias of various sizes. INTERVENTION: Lichtenstein method of tension-free repair using mosquito net mesh by European and African surgeons. Main Outcome Measure Disability-adjusted life-years (DALYs) averted with counterfactual definitions based on precedent and expert opinion. RESULTS: All operations were performed as day cases, with 81 of the patients (71.7%) under local anesthesia and few complications. An average of 9.3 (95% confidence interval [CI], 8.0-10.7) DALYs were averted per person, with a total of 1052 averted in the study. Average cost per patient was $120.02 (95% CI, $117.66-$122.39) from a provider perspective and $102.88 ($88.47-$117.29) from a patient perspective. Cost-effectiveness was $12.88 per DALY averted (95% CI, $10.98-$14.78), which is well below the Ghanaian per capita gross national income ($590). Results were robust to sensitivity analysis and may be refined as further work is done on the burden of disease due to hernias in Africa. CONCLUSIONS: Inguinal hernia repair was cost-effective in the Western Region of Ghana through international collaboration. Research in other settings should test the generalizability of results.

Hunterian Lecture. Hernia surgery: from guidelines to clinical practice.

INTRODUCTION: Over the last 30 years, hernia surgery has developed into an evidence-based practice assisted by the development of guidelines. MATERIALS AND METHODS: Prior to 1993, best practice in the UK was a nylon darn repair under general anaesthesia as an inpatient with prolonged recovery. The publication of The Royal College of Surgeons of England (RCSE) Guidelines on Groin Hernia Repair stimulated debate and coincided with the introduction of mesh hernioplasty and laparoscopic techniques. Further evolution of hernia management has occurred to enable the production of the European Hernia Society (EHS) guidelines in 2008. RESULTS: The EHS guidelines cover all aspects of abdominal wall surgery including: indications for operation; investigations; organising surgical care; techniques; local anaesthesia; after-care, complications and outcome; and information for patients. CONCLUSIONS: Surgeons have many choices when selecting an appropriate hernia operation for an individual patient. The EHS guidelines provide a basis for this decision-making.

Open onlay mesh repair for major abdominal wall hernias with selective use of components separation and fibrin sealant.

BACKGROUND: The objective of the study was to reassess the efficacy of the open onlay technique for repair of major incisional hernias, utilizing the modern adjuncts of components separation and fibrin sealant to reduce the principal complications of seroma and recurrence. Major incisional hernias were defined as >10 cm transverse diameter. METHODS: A prospective audit was applied to 116 patients undergoing open onlay incisional hernia repair during a 2-year period at a single institution. Information was collected concerning operative details, postoperative complications, and recurrence. Clinical review at a median 15.2 months postoperatively was followed by a telephoned structured questionnaire to assess quality of life. All patients with pain or suspected recurrence were recalled for examination. RESULTS: Fascial closure required components separation in 21 (18.1%) patients when tension-free fascia reconstruction was not possible, and fibrin sealant was applied in 22 (18.9%) in whom extensive skin flaps were dissected beyond the semilunar line. Postoperatively, there were 11 (9.5%) seromas and 2 (1.7%) deep wound infections. At 15.2 months' follow-up there were 4 (3.4%) recurrences. CONCLUSIONS: Open onlay mesh repair for major incisional hernias is a versatile operation applicable to all quadrants of the abdominal wall and gives excellent results when used in association with components separation and fibrin sealant.