Effect of oxygen-producing suture material on hypoxic colonic anastomoses in an experimental model.

Background: Anastomotic leak remains a significant cause of morbidity and mortality after colorectal surgery. Among multiple risk factors considered, hypoxia-ischaemia is considered to be a primary cause of intestinal anastomotic leakage. The aim of this experimental study was to assess safety, usability for surgical tasks, and efficacy of a newly developed oxygen-producing suture material in the healing of colonic anastomoses under critical conditions. Methods: An oxygen-producing suture material was produced that is capable of releasing oxygen directly into the surrounding tissue. Off-the-shelf sutures loaded with calcium peroxide nano-crystals and covered with poly(d,l-lactide-co-glycolide) were assessed in vitro and in a rat model of hypoxic colonic anastomosis. Results: In vitro assessment showed that these sutures can increase oxygen levels in a hypoxic environment. Potential oxygen byproducts did not seem to have a negative impact on the viability of intestinal cells. The use of oxygen-producing sutures in vivo resulted in increased tissue oxygen saturation, measured by visible light spectroscopy, and increased mechanical stability of the anastomosis. Conclusion: Oxygen-producing suture material increased tissue oxygen saturation and mechanical stability of colonic anastomosis in a rat model.

Antecedentes: Las fugas anastomóticas siguen siendo una causa importante de morbilidad y mortalidad después de la cirugía colorrectal. Entre los múltiples factores de riesgo, se considera que la hipoxia/isquemia es una de las causas principales de la fuga anastomótica intestinal. El objetivo de este estudio experimental fue evaluar, en condiciones críticas, la seguridad, la facilidad de uso en los procedimientos quirúrgicos y la eficacia en la cicatrización de la anastomosis de colon de un material de sutura productor de oxígeno recientemente desarrollado. Métodos: Hemos producido un material de sutura productor de oxígeno que es capaz de liberar oxígeno directamente en el tejido circundante. Las suturas disponibles en el mercado cargadas con nanocristales de peróxido de calcio (calcium peroxide, CPO) y cubiertas con ácido poliláctico coglicólico (PLGA) se evaluaron in vitro y en un modelo de rata de anastomosis hipóxica de colon. Resultados: La evaluación in vitro mostró que estas suturas pueden aumentar los niveles de oxígeno en un ambiente hipóxico, y que los posibles subproductos de oxígeno no parecen tener un impacto negativo en la viabilidad de las células intestinales. El uso de suturas productoras de oxígeno in vivo causó una elevada saturación de oxígeno en el tejido medida por espectroscopia de luz visible, así como un aumento en la estabilidad mecánica de las anastomosis. Conclusión: El material de sutura productor de oxígeno aumenta la saturación de oxígeno en los tejidos y la estabilidad mecánica de la anastomosis de colon en un modelo de rata.

Anatomy and mechanical properties of the anal sphincter muscles in healthy senior volunteers.

BACKGROUND: A large proportion of age-related fecal incontinence is attributed to weakness or degeneration of the muscles composing the anal continence organ. However, the individual role of these muscles and their functional interplay remain poorly understood. METHODS: This study employs a novel technique based on the combination of MR imaging and FLIP measurements (MR-FLIP) to obtain anatomical and mechanical information simultaneously. Unlike previous methods used to assess the mechanics of the continence organ, MR-FLIP allows inter-individual comparisons and statistical analysis of the sphincter morpho-mechanical parameters. The anatomy as well as voluntary and involuntary mechanical properties of the anal continence organ were characterized in 20 healthy senior volunteers. RESULTS: Results showed that the external anal sphincter (EAS) forms a funnel-like shape with wall thickness increasing by a factor of 2.5 from distal (6 ± 0 mm) to proximal (15 ± 3 mm). Both voluntary and involuntary mechanical properties in this region correlate strongly with the thickness of the muscle. The positions of least compliance and maximal orifice closing were both located toward the proximal EAS end. In addition, maximal contraction during squeeze maneuvers was reached after 2 s, but high muscle fatigue was measured during a 7 s holding phase, corresponding to about 60% loss of the energy produced by the muscles during the contraction phase. CONCLUSIONS: This work reports baseline parameters describing the morpho-mechanical condition of the sphincter muscle of healthy elderly volunteers. New parameters were also proposed to quantify the active properties of the muscles based on the mechanical energy associated with muscle contraction and fatigue. This information could be used to assess patients suffering from AI or for the design of novel implants.

MR-FLIP: a new method that combines a functional lumen imaging probe with anatomical information for spatial compliance assessment of the anal sphincter muscles.

AIM: Continence results from a complex interplay between anal canal (AC) muscles and sensorimotor feedback mechanisms. The passive ability of the AC to withstand opening pressure - its compliance - has recently been shown to correlate with continence. A functional lumen imaging probe (FLIP) is used to assess AC compliance, although it provides no anatomical information. Therefore, assessment of the compliance specific anatomical structures has not been possible, and the anatomical position of critical functional zones remains unknown. In addition, the FLIP technique assumes a circular orifice cross-section, which has not been shown for the AC. To address these shortcomings, a technique combining FLIP with a medical imaging modality is needed. METHOD: We implemented a new research method (MR-FLIP) that combines FLIP with MR imaging. Twenty healthy volunteers underwent MR-FLIP and conventional FLIP assessment. MR-FLIP was validated by comparison with FLIP results. Anatomical markers were identified, and the cross-sectional shape of the orifice was investigated. RESULTS: MR-FLIP provides compliance measurements identical to those obtained by conventional FLIP. Anatomical analysis revealed that the least compliant AC zone was located at the proximal end of the external anal sphincter (EAS). The cross-sectional shape of the AC was found to deviate only slightly from circularity in healthy volunteers. CONCLUSION: The proposed method is equivalent to classical FLIP. It establishes for the first time direct mapping between local tissue compliance and anatomical structure, which is key to gaining novel insights into (in)continence. In addition, MR-FLIP provides a tool for better understanding conventional FLIP measurements in the AC by quantifying its limitations and assumptions.

Negative appendicectomy and perforation rates in patients undergoing laparoscopic surgery for suspected appendicitis.

BACKGROUND: Despite widespread use of imaging technologies including ultrasonography and computed tomography, rates of negative appendicectomy and perforated appendicitis remain high. This trend analysis examined whether rates of negative appendicectomy and perforated appendicitis have decreased over time, and sought to evaluate clinical predictors associated with negative appendicectomy and perforated appendicitis. METHODS: This analysis was based on the prospective database of the Swiss Association of Laparoscopic and Thoracoscopic Surgery (SALTS). All patients aged 12 years and over undergoing emergency laparoscopic appendicectomy between 1995 and 2006 were included. Unadjusted and risk-adjusted logistic regression analyses were performed. RESULTS: A total of 7964 patients underwent laparoscopic appendicectomy, of whom 7452 (93.6 per cent) had acute appendicitis and 512 (6.4 per cent) had a macroscopically normal appendix. Perforation occurred in 1230 (16.5 per cent) of those with appendicitis. In multivariable analysis, younger age (12-18 years), female sex, absence of local or generalized peritonitis and an early point during the study period were significant predictors of negative appendicectomy. For perforated appendicitis, significant predictors included age over 36 years, presence of localized or generalized peritonitis, and high American Society of Anesthesiologists grade. The rate of negative appendicectomy decreased from 12.7 per cent in 1995 to 2.8 per cent in 2006, there being a significant reduction in both unadjusted and risk-adjusted analyses (P < 0.001 for trend). In adjusted analyses, the rate of perforated appendicitis did not increase significantly over time. CONCLUSION: The rate of negative appendicectomy decreased over time, without an accompanying increase in perforated appendicitis. The risk of having a negative appendicectomy was highest in girls aged 12-18 years without local or generalized peritonitis during the early study period, whereas perforation was associated with age over 36 years, presence of localized or generalized peritonitis, and greater co-morbidity. Copyright © 2011 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.

[New approaches to the surgical treatment of diffuse peritonitis]. / Neue Ansätze in der chirurgischen Therapie der diffusen Peritonitis.

OBJECTIVE: We intend to analyze if additional treatment concepts are necessary in any case as a part of the standard therapy next to the well established principle of source control in the treatment of secondary peritonitis. DESIGN: A treatment concept with early intervention, source control and extensive intraoperative lavage (20-301) should be evaluated as a standard procedure in a prospective survey. Additional treatment concepts will be applied only for special reason (on demand). RESULTS: From 11/1993 to 9/1997 241 patients with diffuse peritonitis were treated with the concept mentioned above. Additional treatment concepts as continuous postoperative lavage (n = 20) and staged lavage (n = 4) were applied as primary treatment in 24 patients only (10%), mainly for impossibility of source control and evisceration. Source control at the initial operation was possible in 216 patients (90%). Due to secondary evisceration 3 patients had to undergo laparostomy for staged lavage later. Severity of peritonitis was determined according to the Mannheim Peritonitis Index (median 26, range 15-43). The primary causes of peritonitis were perforation, leakage and abscess after operation (n = 56), followed by diverticular (n = 42) and gastric or duodenal perforation (n = 39). The hospital mortality rate was 14% in the whole group, and the postoperative morbidity rate was 39%. CONCLUSIONS: Due to progress in intensive care and antibiotic treatment only a few patients (ca. 10%) need additional therapies such as postoperative or staged lavage. Surgical source control in combination with intraoperative lavage is sufficient in most of the patients with diffuse peritonitis.