Jens Otto

University Hospital RWTH Aachen , Aachen, North Rhine-Westphalia, Germany

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Publications (53)96.07 Total impact

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    ABSTRACT: After two-dimensional plane MRI-visible mesh implants could be successfully visualized in phantom and small animal model, the aim of the underlying study was to explore the feasibility of an MRI visualization of complex three-dimensional mesh geometry in close contact to the intestine. We therefore used a MR-visible three-dimensional intra-peritoneal stoma (IPST) mesh in a porcine model.
    Hernia : the journal of hernias and abdominal wall surgery. 06/2014;
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    ABSTRACT: Shrinkage and deformation of mesh implants used for hernia treatment can be the cause of long-term complications. The purpose of this study was to quantify noninvasively time-dependent mesh shrinkage, migration, and configuration changes in patients who were surgically treated for inguinal hernia using magnetic resonance imaging (MRI)-visible mesh implants. In an agarose phantom, meshes in different shrinkage and folding conditions were used to validate the quantification process. Seven patients who were surgically (3 bilaterally) treated for inguinal hernia using iron-loaded mesh implants were prospectively examined using MRI. Gradient echo sequences in sagittal and transverse orientations were performed on day 1 after surgery and at day 90. The mesh-induced signal voids were semiautomatically segmented and a polygonal surface model was generated. A comparison of area and centroid position was performed between the 2 calculated surfaces (day 1 vs day 90). The phantom study revealed a maximum deviation of 3.6% between the MRI-based quantification and the actual mesh size. All 10 implants were successfully reconstructed. The mean (SD) observed mesh shrinkage 90 days after surgery was 20.9% (7.1%). The mean (SD) centroid movement was 1.17 (0.47) cm. Topographic analysis revealed mean (SD) local configuration changes of 0.23 (0.03) cm. In this study, significant mesh shrinkage (20.9%) but marginal changes in local mesh configuration occurred within 90 days after mesh implantation. Centroid shift of the mesh implant can be traced back to different patient positioning and abdominal distension. The developed algorithm facilitates noninvasive assessment of key figures regarding MRI-visible meshes. Consequently, it might help to improve mesh technology as well as surgical skills.
    Investigative radiology 03/2014; · 4.85 Impact Factor
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    ABSTRACT: Recurrence rate of hiatal hernia can be reduced with prosthetic mesh repair; however, type and shape of the mesh are still a matter of controversy. The purpose of this study was to investigate the biomechanical properties of four conventional meshes: pure polypropylene mesh (PP-P), polypropylene/poliglecaprone mesh (PP-U), polyvinylidenefluoride/polypropylene mesh (PVDF-I), and pure polyvinylidenefluoride mesh (PVDF-S). Meshes were tested either in warp direction (parallel to production direction) or perpendicular to the warp direction. A Zwick testing machine was used to measure elasticity and effective porosity of the textile probes. Stretching of the meshes in warp direction required forces that were up to 85-fold higher than the same elongation in perpendicular direction. Stretch stress led to loss of effective porosity in most meshes, except for PVDF-S. Biomechanical impact of the mesh was additionally evaluated in a hiatal hernia model. The different meshes were used either as rectangular patches or as circular meshes. Circular meshes led to a significant reinforcement of the hiatus, largely unaffected by the orientation of the warp fibers. In contrast, rectangular meshes provided a significant reinforcement only when warp fibers ran perpendicular to the crura. Anisotropic elasticity of prosthetic meshes should therefore be considered in hiatal closure with rectangular patches. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 03/2014; · 2.31 Impact Factor
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    ABSTRACT: Background: Application of a mesh in presence of pneumoperitoneum may cause deformation or wave formation when gas is released. Moreover, mesh shrinkage during subsequent wound healing cannot be detected in vivo without invasive diagnostics. Using MRI-visible polyvinylidene fluoride (PVDF) mesh, the extend of mesh deformation and shrinkage could be objectified by MRI for the first time. Materials and Methods: Laparoscopic intraperitoneal onlay mesh (IPOM) implantation was performed in 10 female rabbits using ferro-oxide loaded PVDF meshes. MRI measurements were performed postoperatively at days 1 and 90. After three-dimensional reconstruction of all MRI images the total surface and the effective surface of the implanted mesh were explored and calculated computer-assisted. Results: In all cases, the mesh could be identified in MRI. The subsequent three-dimensional reconstruction always allowed a calculation of the mesh area. In relation to the original size of the used textile implant, we found neither a significant reduction of the effective mesh surface after release of the pneumoperitoneum at day 1 after laparoscopic surgery nor a significant change of the total surface of this large pore mesh by the end of the observation period. Conclusions: In vivo investigation of mesh surface via MRI could exclude a significant initial reduction of the effective mesh surface after release of pneumoperitoneum, in this IPOM rabbit model. A further subsequent shrinkage of these large pore PVDF meshes could be excluded, as well. Imaging of MRI-visible IPOM mesh turned out to be a sufficient tool to objectify mesh configuration and position in vivo. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 01/2014; · 2.31 Impact Factor
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    ABSTRACT: PURPOSE Surgical hernia treatments using polymer based mesh implants are one of the most frequent operations worldwide. As the implants are invisible using conventional imaging methods, iron-oxides were integrated into the mesh polymer base material to visualize them in MRI. The purpose of this study is to evaluate the conspicuity of these mesh implants in patients treated for inguinal hernia and assessment of immediate post surgical mesh configuration. METHOD AND MATERIALS Approved by the ethics committee, 13 patients treated with iron-loaded mesh implants via laparoscopic or via open surgical procedure were prospectively examined beginning March 2012. MRI was conducted one day after surgery at a 1.5 Tesla scanner using three different conventional gradient echo (GRE1-3) and one T2-weighted turbospin echo (TSE) sequences. Three radiologists independently assessed mesh conspicuity and diagnostic value by the following criteria using a 4-point-scale: visual contrast-to-noise ratio, conspicuity to air artifacts, and diagnostic quality rating with respect to the mesh and to the surrounding anatomy. Mesh deformation and coverage of the hernia were visually assessed and rated using a 5-point semi-quantitative scoring system. Additionally, mesh deformation and localisation in relation to the hernia were rated. Using linear contrast and mixed models, statistical analysis was performed. RESULTS MRI successfully visualized all implants. GRE sequences clearly exhibited the mesh implants as a thick hypointense line. GRE1 was rated best (3.8; p<0.05) for diagnostic quality with respect to the mesh whereas GRE3 was suited best for combined evaluation of mesh and surrounding anatomy (2.9; p<0.05). TSE was preferred for exclusive evaluation of the anatomy (3.8; p<0.05) but insufficient in mesh delineation. Local air slightly reduced mesh delineation. Overall, in both implantation techniques, the meshes exhibited mild to moderate deformations. CONCLUSION The combination of iron-loaded implants and MRI facilitates mesh visualization for the first time in patients. After surgical hernia repair, mesh localization and configuration can be clearly assessed. For MRI protocol, we propose a combination of different gradient echo sequences and T2-weighted TSE sequences. CLINICAL RELEVANCE/APPLICATION Using this new technique, MRI could become a non-invasive alternative to open surgical exploration if mesh-related complications after hernia surgery are suspected.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: OBJECTIVES: Until today, there have been no conventional imaging methods available to visualize surgical mesh implants and related complications. In a new approach, we incorporated iron particles into polymer-based implants and visualized them by magnetic resonance imaging (MRI).After clinical approval of such implants, the purposes of this study were to evaluate the MRI conspicuity of such iron-loaded mesh implants in patients treated for inguinal hernias and to assess the immediate postsurgical mesh configuration. MATERIALS AND METHODS: Approved by the ethics committee, in this prospective cohort study, 13 patients (3 patients with bilateral hernia treatment) were surgically treated for inguinal hernia receiving iron-loaded mesh implants between March and October 2012. The implants were applied via laparoscopic technique (transabdominal preperitoneal technique; n = 8, 3 patients with bilateral hernia treatment) or via open surgical procedure (Lichtenstein surgery; n = 5). Magnetic resonance imaging was performed 1 day after the surgery at a 1.5-T scanner (Achieva; Philips, Best, The Netherlands) with a 16-channel receiver coil using 3 different gradient echo sequences (first gradient echo sequence, second gradient echo sequence, and third gradient echo sequence [GRE1-3]) and 1 T2-weighted turbo spin-echo sequence (T2wTSE). Three radiologists independently evaluated mesh conspicuity and diagnostic value with respect to different structures using a semiquantitative scoring system (1, insufficient; 2, sufficient; 3, good; 4, optimal). Mesh deformation and coverage of the hernia were visually assessed and rated using a 5-point semiquantitative scoring system. Statistical analysis was performed using mixed models and linear contrast. RESULTS: All 16 implants were successfully visualized by MRI. On gradient echo sequences, the mesh is clearly delineated as a thick hypointense line. On T2wTSE, the mesh was depicted as a faint hypointense line, which was difficult to identify. The first gradient echo sequence was rated best for visual conspicuity (mean [SD], 3.8 [0.4]). T2-weighted turbo spin-echo sequence was preferred for evaluation of the surrounding anatomy (mean [SD], 3.7 [0.3]). For the combined assessment of both mesh and anatomy, GRE3 was rated best (mean [SD], 2.9 [0.7]). Local air slightly reduced mesh delineation (lowest mean [SD] rating, 2.9 [0.7] for GRE3). Overall, in both implantation techniques, the meshes exhibited mild to moderate deformations (mean [SD], 3.3 [0.4], 3.1 [0.3], and 2.8 [0.3] on average with open technique, 2.7 [0.3], 2.7 [0.2], and 2.3 [0.3] with laparoscopic technique). Coverage of the hernia was achieved in 15 of the 16 implants. CONCLUSIONS: Combining iron-loaded implants and MRI, we achieved mesh visualization for the first time in patients. For MRI protocol, we propose a combination of different gradient echo sequences and T2-weighted turbo spin-echo sequences: first gradient echo sequence for mesh configuration, T2wTSE for anatomy assessment, and GRE3 for evaluation of hernia coverage and mesh localization. Using our approach, MRI could become a noninvasive alternative to open surgical exploration if mesh-related complications were suspected.
    Investigative radiology 05/2013; · 4.85 Impact Factor
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    ABSTRACT: Purpose: Use of textile structures for reinforcement of pelvic floor structures has to consider mechanical forces to the implant, which are quite different to the tension free conditions of the abdominal wall. Thus, biomechanical analysis of textile devices, have to include the impact of strain on stretchability and effective porosity. Material and methods: Prolift® and Prolift + M®, developed for tension free conditions, were tested by measuring stretchability and effective porosity applying mechanical strain. For comparison we used Dynamesh - PR4®, which was designed for pelvic floor repair to withstand mechanical strain. Results: Prolift® at rest showed moderate porosity with little stretchability but complete loss of effective porosity at strain of 4.9 N/cm. Prolift + M® revealed an increased porosity at rest, but at strain showed high stretchability, with subsequent loss of effective porosity at strain of 2.5 N/cm. Dynamesh PR4® preserved its high porosity even under strain, but as consequence of limited stretchability. Conclusions: Though in tension free conditions Prolift® and Prolift + M® can be considered as large pore class I meshes, application of mechanical strain rapidly lead to collapse of pores. The loss of porosity at mechanical stress can be prevented by constructions with high structural stability. Assessment of porosity under strain was found helpful to define requirements for pelvic floor devices. Clinical studies have to prove whether devices with high porosity as well as high structural stability can improve the patients' outcome.
    Journal of Biomedical Materials Research Part A 04/2013; · 2.83 Impact Factor
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    ABSTRACT: PURPOSE: Polymer-based textile meshes for abdominal hernia treatment are invisible by conventional imaging methods, including magnetic resonance imaging (MRI). Integration of iron particles in the mesh base material allows MRI visualization of meshes. Positive-contrast susceptibility imaging (PCSI) was implemented to separate susceptibility-induced voids from proton-deficient voids. The purpose of this study was to compare PCSI with conventional gradient echo and turbo spin echo (TSE) sequences for the in vivo assessment of superparamagnetic iron oxide particle-loaded surgical meshes in an animal model. METHODS AND MATERIALS: Iron-loaded polymer meshes were implanted into the abdominal wall of 10 rabbits. At days 1, 30, and 90 after surgery, conventional gradient echo, TSE, and PCSI were performed at 1.5 T in the sagittal and axial planes. Images were scored by 2 radiologists with respect to mesh visibility, delineation of the surrounding tissue, differentiation from other structures, and overall diagnostic use, on a 4-point scale ranging from 1 (insufficient) to 4 (excellent). The results were compared using Wilcoxon signed-rank tests. The mesh shape, possible deformation or fracture, and possible mesh migration were evaluated on the different pulse sequences and compared with the results at surgery and autopsy. RESULTS: The iron-loaded meshes appeared as hypointense signal voids on gradient echo sequences, as a hyperintense line on PCSI, and as a very thin dark line on TSE images. In all animals, a precise depiction of the mesh location and its spatial configuration and integrity was possible by MRI and confirmed by surgical and autopsy results. In all 4 categories and at all 3 time points of imaging, image quality scores were significantly higher for gradient echo imaging (range, 3.60-3.80) compared with PCSI (range, 3.12-3.42) and TSE (range, 1.64-1.89). At day 90, the image quality ratings of gradient echo and PCSI were comparable. In 2 cases, the complete delineation of mesh borders was impossible because of signal voids of adjacent anatomical structures, whereas PCSI helped achieve this differentiation. CONCLUSION: In this rabbit model of iron-loaded implanted abdominal meshes, standard gradient echo imaging was best suitable to assess implant location, integrity, and configuration. In 2 of 10 animals, PCSI helped achieve a complete delineation of mesh borders.
    Investigative radiology 01/2013; · 4.85 Impact Factor
  • Biomedizinische Technik/Biomedical Engineering 09/2012; · 1.16 Impact Factor
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    ABSTRACT: BACKGROUND: The aim of this study was to analyze the early postoperative outcome of esophageal cancer treated by subtotal esophageal resection, gastric interposition and either intrathoracic or cervical anastomosis in a single center study. METHODS: 72 patients who received either a cervical or intrathoracic anastomosis after esophageal resection for esophageal cancer were matched by age and tumor stage. Collected data from these patients were analyzed retrospectively regarding morbidity and mortality rates. RESULTS: Anastomotic leakage rate was significantly lower in the intrathoracic anastomosis group than in the cervical anastomosis group (4 of 36 patients (11 %) vs. 11 of 36 patients (31 %); p = 0.040). The hospital stay was significantly shorter in the intrathoracic anastomosis group compared to the cervical anastomosis group (14 (range 10-110) vs. 26 days (range 12 - 105); p = 0.012). Wound infection and temporary paresis of the recurrent laryngeal nerve occurred significantly more often in the cervical anastomosis group compared to the intrathoracic anastomosis group (28 % vs. 0 %; p = 0.002 and 11 % vs. 0 %; p = 0.046). The overall Inhospital mortality rate was 6 % (4 of 72 patients) without any differences between the study groups. CONCLUSIONS: The present data support the assumption that the transthoracic approach with an intrathoracic anastomosis compared to a cervical esophagogastrostomy is the safer and more beneficial procedure in patients with carcinoma of the lower and middle third of the esophagus due to a significant reduction of anastomotic leakage, wound infection, paresis of the recurrent laryngeal nerve and shorter hospital stay.
    World Journal of Surgical Oncology 08/2012; 10(1):159. · 1.09 Impact Factor
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    ABSTRACT: Several decades ago, the beneficial effects of goal-directed therapy, which include decompressive laparotomy (DL) and open abdomen procedures in cases of intra-abdominal hypertension (IAH) in children, were proven in the context of closures of abdominal wall defects and large-for-size organ transplantations. Different neonatologic and pediatric disease patterns are also known to be capable of increasing intra-abdominal pressure (IAP). Nevertheless, a considerable knowledge transfer regarding such risk factors has hardly taken place. When left undetected and untreated, IAH threatens to evolve into abdominal compartment syndrome (ACS), which is accompanied by a mortality rate of up to 60% in children. Therefore, the present study looks at the recognition and knowledge of IAH/ACS among German pediatric intensivists. In June 2010, a questionnaire was mailed to the heads of pediatric intensive care units of 205 German pediatric hospitals. The response rate was 62%. At least one case of IAH was reported by 36% of respondents; at least one case of ACS, by 25%. Compared with adolescents, younger critically ill children appeared to develop IAH/ACS more often. Routine measurements of IAP were said to be performed by 20% of respondents. Bladder pressure was used most frequently (96%) to assess IAP. Some respondents (17%) only measured IAP in cases of organ dysfunction and failure. In 2009, the year preceding this study, 21% of respondents claimed to have performed a DL. Surgical decompression was indicated if signs of organ dysfunction were present. This was also done in cases of at least grade III IAH (IAP > 15 mmHg) without organ impairment. Although awareness among pediatricians appears to have been increasing over the last decade, definitions and guidelines regarding the diagnosis and management of IAH/ACS are not applied uniformly. This variability could express an ever present lack of awareness and solid prospective data.
    Annals of intensive care. 07/2012; 2 Suppl 1:S8.
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    ABSTRACT: Abdominal compartment syndrome (ACS) is a life threatening condition that may affect any critically ill patient. Little is known about the recognition and management of ACS in Germany. A questionnaire was mailed to departments of surgery and anesthesia from German hospitals with more than 450 beds. Replies (113) were received from 222 eligible hospitals (51%). Most respondents (95%) indicated that ACS plays a role in their clinical practice. Intra-abdominal pressure (IAP) is not measured at all by 26%, while it is routinely done by 30%. IAP is mostly (94%) assessed via the intra-vesical route. Of the respondents, 41% only measure IAP in patients expected to develop ACS; 64% states that a simpler, more standardized application of IAP measurement would lead to increased use in daily clinical practice. German anesthesiologists and surgeons are familiar with ACS. However, approximately one fourth never measures IAP, and there is considerable uncertainty regarding which patients are at risk as well as how often IAP should be measured in them.
    Annals of intensive care. 07/2012; 2 Suppl 1:S7.
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    ABSTRACT: Conventional radiological methods, including magnetic resonance imaging (MRI), fail to visualize polymeric surgical mesh implants because of small thread dimensions and material characteristics. For MRI delineation of such meshes, superparamagnetic iron oxide particles (SPIOs) are integrated in the mesh polymer. Usually, if SPIOs are used as an intravenous contrast agent, they increase the R1 and R2 of adjacent protons. It can be assumed that embedding SPIOs in polymers alters their molecular dynamics. The aim of this study was to investigate the influence of SPIO integration in polymer on the relaxation of adjacent protons. Polymer threads were placed in an agarose phantom. At 1.5 T, R1, R2, and R2* maps were calculated from multi inversion-recovery spin echo, multi-spin echo, and multi-gradient echo images, respectively. The threads were aligned parallel or orthogonal to B(0). No impact of SPIO on proton R1 and R2 was observed. R2* was increased by the SPIO-loaded threads. R1 and R2 amplitude maps showed a magnetic susceptibility difference of 0.97 ppm/(mg SPIO/g polymer) around SPIO-loaded threads. In contrast to SPIO in aqueous solutions, polymer-embedded SPIO do not affect proton R1 and R2. However, embedded SPIO generate strong local static magnetic field gradients. Thus, SPIO integration is suitable to control the magnetic susceptibility of polymer threads. This can be exploited to visualize implanted polymer-based meshes in MRI using R2* susceptible sequences. Because no impact on R1 and R2 of adjacent protons by SPIO embedded in mesh threads was observed, structures adjacent to implanted meshes will be observable in R1 and R2 maps.
    Investigative radiology 04/2012; 47(6):359-67. · 4.85 Impact Factor
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    ABSTRACT: To reduce infection rates after mesh implantation antibiotic-coated meshes were designed. The aim of the study was to analyze biocompatibility and in vitro efficiency of a modified gentamicin-supplemented polyvinylidenfluoride mesh. Twenty rats were randomized to two groups (PVDF group and Genta group). Mesh material was implanted subcutaneously. Blood samples were taken to determine the gentamicin serum concentration. Seven and 90 days after mesh implantation, animals were euthanized. The inflammatory tissue response was characterized by analyzing the foreign body granuloma. Cellular immune response was analyzed by immunohistochemical investigations. The collagen type I/III ratio was estimated by crosspolarization microscopy. In vitro agar diffusion test, suspension test, and gentamicin release were characterized. Agar diffusion and suspension test showed efficient antibiotic effects of the mesh in vitro. Serum concentrations of gentamicin showed a peak value 1 h postoperatively with a decline within the next day. The total size of the granuloma was significantly smaller in the Genta group compared to the PVDF group at both points of time. Except of a short period of increased expression of CD68 in the Genta group after 7 days, no further difference was found analyzing cellular immune response. The collagen type I/III ratio was widely constant analyzing the two mesh types without significant differences comparing both mesh materials. A significantly decreased foreign body granuloma formation compared to the pure PVDF mesh group was found. In vitro analysis showed efficient antibiotic effects of the Gentamicin supplementation compared to the pure PVDF mesh.
    Journal of Biomedical Materials Research Part A 02/2012; 100(5):1195-202. · 2.83 Impact Factor
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    ABSTRACT: For the development of a surgical mesh implant that is visible in magnetic resonance imaging (MRI), superparamagnetic iron oxides (SPIOs) are integrated into the material of the mesh. In order to get a high quality mesh regarding both mechanical and imaging properties, a narrow size distribution and homogenous spatial distribution, as well as a strong magnetization of SPIOs within the filament of the mesh are required. In this work, six different samples of SPIOs composed of a magnetite core are synthesized with and without stabilizing dodecanoic acid and analyzed using a superconducting quantum interference device (SQUID), transmission electron microscope (TEM) and a magnetic force microscope (MFM) to determine the properties that are beneficial for the assembly and imaging of the implant. These analyses show the feasibility of visualization of surgical implants with incorporated SPIOs and the influence of the agglomeration of SPIOs on their magnetization and on a homogenous spatial distribution within the polymer of the mesh.
    Current pharmaceutical biotechnology 01/2012; 13(4):545-51. · 3.40 Impact Factor
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    ABSTRACT: Prosthetic mesh implants are widely used in hernia surgery. To show long-term mesh-related complications such as shrinkage or adhesions, a precise visualization of meshes and their vicinity in vivo is important. By supplementing mesh fibers with ferro particles, magnetic resonance imaging (MRI) can help to delineate the mesh itself. This study aimed to demonstrate and quantify time-dependent mesh shrinkage in vivo by MRI. Polyvinylidenfluoride (PVDF) meshes with incorporated superparamagnetic iron oxides (SPIOs) were implanted as an abdominal wall replacement in 30 rats. On days 1, 7, 14, or 21, MRI was performed using a gradient echo sequence with repetition time (TR)/echo time (TE) of 50/4.6 and a flip angle of 20°. The length, width, and area of the device were measured on axial, coronal, and sagittal images, and geometric deformations were assessed by surgical explantation. In all cases, the meshes were visualized and their area estimated by measuring the length and width of the mesh. The MRI presented a mean area shrinkage in vivo of 13% on day 7, 23% on day 14, and 23% on day 21. Postmortem measurements differed statistically from MRI, with a mean area shrinkage of 23% on day 7, 28% on day 14, and 30% on day 21. Ex vivo measurements of shrinkage showed in vivo measurements to be overestimated approximately 8%. Delineation of the mesh helped to show folding or adhesions close to the intestine. Loading of surgical meshes with SPIOs allows their precise visualization during MRI and guarantees an accurate in vivo assessment of their shrinkage. The authors' observation clearly indicates that shrinkage in vivo is remarkably less than that shown by illustrated explantation measurements. The use of MRI with such meshes could be a reliable technique for checking on proper operation of implanted meshes and showing related complications, obviating the need for exploratory open surgical revision.
    Surgical Endoscopy 12/2011; 26(5):1468-75. · 3.43 Impact Factor
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    ABSTRACT: Laparoscopic mesh repair of inguinal and incisional hernias has been widely adopted. Nevertheless, knowledge about the impact of pneumoperitoneum on mesh integration is rare. The present study investigates pressure and gas-dependent effects of pneumoperitoneum on adhesion formation and biomaterial integration in a standardized animal model. Laparoscopic intraperitoneal onlay mesh implantation (IPOM) was performed in 32 female chinchilla rabbits using CO(2) or helium for pneumoperitoneum. Intra-abdominal pressures were 3 or 6 mmHg. Animals were killed after 21 days, and the abdominal wall was explanted for subsequent histopathological examinations. Adhesions were assessed qualitatively with a scoring system, and the adhesion surface was analyzed semiquantitatively by planimetry. Infiltration of macrophages (CD68), expression of matrix metalloproteinase 13 (MMP-13), and cell proliferation (Ki67) were analyzed at the mesh to host interface by immunohistochemistry. The collagen type I/III ratio was analyzed by cross-polarization microscopy to determine the quality of mesh integration. After 21 days, perifilamental infiltration with macrophages (CD68) and percentage of proliferating cells (Ki67) were highest after 6 mmHg of CO(2) pneumoperitoneum. The extent of adhesions, as well as the expression of MMP-13 and the collagen type I/III ratio, were similar between groups. Our experiments showed no pressure or gas-dependent alterations of adhesion formation and only minor effects on biomaterial integration. Altogether, there is no evidence for a clinically negative effect of CO(2) pneumoperitoneum.
    Surgical Endoscopy 06/2011; 25(11):3605-12. · 3.43 Impact Factor
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    ABSTRACT: Abdominal hernia repair is the most frequently performed operation in surgery. Mesh repair in hernia surgery has become an integral component. Although meshes made of PVDF are already in clinical use, so far no data of long-term biocompability are available. In this study a PVDF mesh was compared to a polypropylene mesh with regard to its long-term biocompatibility. A total of 28 rats were randomized to two groups. Mesh material was implanted subcutaneously; animals were euthanized seven days and six months postoperatively. The quantity of inflammatory tissue response was characterized by measuring the diameter of the foreign body granuloma. Furthermore quality of cellular immune response (T-lymphocytes, macrophages, and neutrophils), and inflammation (COX-2) was analyzed by immunohistochemistry. Furthermore the collagen type I/III ratio was determined. Macrophages, T-lymphocytes, neutrophiles, and COX-2 declined significantly up to six months postoperatively in comparison to day 7 for both PVDF and PP meshes, and in both groups the collagen ratio increased significantly in the course of time. PVDF meshes showed a foreign body granuloma size significantly reduced compared to PP (7 days: 20 ± 2 μm vs. 27 ± 2 μm; 6 months 15 ± 2 μm vs. 22 ± 3 μm; p < .001). However no significant differences were found analyzing cellular response six months postoperatively. Our current data suggest that even in the long-term course after six months and despite a higher effective surface of the PVDF samples it showed a smaller foreign body granuloma than with PP whereas the cellular response was similar.
    Journal of Investigative Surgery 01/2011; 24(6):292-9. · 1.32 Impact Factor
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    ABSTRACT: Anastomotic failure is one of the most frequent complications in abdominal surgery. During anastomotic healing. the strength of the intestinal tissue nearby is closely related to the accumulation of collagen in interlinked scar tissue. This in turn is influenced, among other things, by single groups of matrixmetalloproteinases, especially collagenases (MMP-1, -8, and -13) and gelatinases (MMP-2 and -9). EPO is known to induce the expression of tissue-inhibitor-of-matrixmetalloproteinases-1 (TIMP-1) and thereby to down-regulate MMPs. We used a rat as an experimental model and applied a high dose of EPO (5U/g BW s.c.), one dose 24 h before operation (as pre-conditioning) and one dose directly after performing a colonic anastomosis. After 3 and after 5 d, respectively, immunohistochemical stainings for MMP-2, -8, and -9 as well as TIMP-1 were carried out and evaluated semiquantitatively for each layer of the colonic wall. Sirius-red staining and cross-polarization microscopy were evaluated and the collagen I/III ratio calculated. Anastomotic and colonic tissue distal to the anastomosis were used to determine collagen content. We found increased bursting pressure 5 d post-surgery after applying erythropoietin. It was thus shown that EPO influences collagen metabolism and changes the collagen I/III ratio in the colon distal to the anastomosis. The evaluation of immunohistochemistry did not show the expected ubiquitous up-regulation of TIMP-1 and down-regulation of MMPs. Nevertheless, correlations between TIMP-1, MMP-8, and collagen I/III ratio could only be established after the application of EPO. Contrary to our hypothesis, the picture of TIMP-1 and of the regulation of the MMPs after the application of EPO is not as clear as expected. EPO improves anastomotic bursting strength and the correlation of TIMP-1, MMP-8, and collagen type I/III ratio can only be seen after the application of EPO.
    Journal of Surgical Research 10/2010; 163(2):e67-72. · 2.02 Impact Factor
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    ABSTRACT: Zielsetzung: Bauchdeckenerweiterungsplastiken zur Revision bei Omphalozelen und Gastroschisis sind Paradebeispiele einer adäquaten Therapie bei Intraabdomineller Hypertonie (IAH) und Abdominellem Kompartmentsyndrom (AKS) und haben zu einer Mortalitätsreduktion von 80 auf 10% geführt. Andere in der pädiatrischen Intensivmedizin typische Krankheitsbilder wie NEC, Verbrennung, Trauma, Sepsis und Schock können gleichermaßen zu IAH führen, frühzeitige Dekompressionen sind in Bezug auf diese Entitäten aber weiterhin die Ausnahme. In Vorstudien konnte herausgefunden werden, dass in einem porcinen Modell des AKS eine Druckbelastung von über 18h zu mittel- bis hochgradigen Organschäden führt, selbst wenn durch intensivierte Volumentherapie das Cardiac Output (CO) aufrecht erhalten wird und infolge dessen klinische „Kardinalsymptome“ eines AKS wie Oligurie bzw. Anurie vermieden werden. In der vorliegenden experimentellen Studie wurde untersucht, ob auch eine kurzfristige Erhöhung des IAD über einen Zeitraum von 6 bzw. 12 Stunden trotz erhaltenem Herzzeitvolumen zu Organschäden führt. Methodik: 16 männliche Schweine (50kg, SD 3.8) wurden mittels Ketamin und Pentobarbital analgosediert und volumenkontrolliert ventiliert. Mittels CO2-Pneumoperitoneum wurde der intraabdominelle Druck (IAD) über 6 bzw. 12h (je n=6) auf 30mmHg erhöht. In der Kontrollgruppe (n=4) blieb der IAD unverändert (3.9mmHg, SD 5.4). Kontinuierlich wurden Herzfrequenz (HF), mittlerer arterieller Druck (MAD), Zentralvenendruck (ZVD), CO und Beatmungsspitzendruck (PIP) registriert. Zusätzlich zum Flüssigkeitserhalt (2ml/kg/h) wurde den Prüftieren bedarfsadaptiert Ringer-Lösung infundiert, so daß das CO auf dem Level der Kontrolltiere verblieb. Am Versuchsende wurden die Tiere euthanasiert und sektioniert. Gewebeschäden an Lunge, Herz, Nieren, Leber und Magen wurden 4-stufig quantifiziert als kein, gering-, mittel- oder hochgradig. Darm-Proben wurden nach der Park-Klassifikation beurteilt. Die statistische Auswertung erfolgte mittels ANOVA und Mann-Whitney-U. Die Signifikanzgrenze wurde mit p<0.05 festgelegt und im Falle multipler gepaarter Tests nach Bonferroni angehoben. Ergebnis: ZVD und PIP stiegen signifikant an, während die übrigen hämodynamischen Parameter stabil blieben. Im Vergleich zur Kontrollgruppe fanden sich in beiden Prüfgruppen signifikante Schäden an Lunge, Nieren, Leber, Magen (nur 12h-Gruppe) und Darm. Lediglich das Myokard zeigte keine relevanten Läsionen. In der 12h-Gruppe waren die Schäden nicht-signifikant stärker ausgeprägt als in der 6h-Gruppe. Schlussfolgerung: Eine nur kurzfristige IAD-Erhöhung über 6h führt zu histologischen Organschäden, selbst wenn durch intensivierte Volumentherapie das CO aufrecht erhalten wird. Für den klinischen Alltag implementieren diese Ergebnisse die Notwendigkeit einer schnellstmöglichen Dekompression bei Vorliegen eines kritisch erhöhten IAD zur Prävention multipler Organdysfunktionen.
    Anasthesiologie und Intensivmedizin 09/2010; 51(Suppl. Nr. 6):S741. · 0.50 Impact Factor

Publication Stats

224 Citations
96.07 Total Impact Points


  • 2008–2014
    • University Hospital RWTH Aachen
      • Department of Neurology
      Aachen, North Rhine-Westphalia, Germany
  • 2012
    • University of Iowa Children's Hospital
      Iowa City, Iowa, United States
    • Kinderklinik Dritter Orden Passau
      Passau, Bavaria, Germany
  • 2004–2012
    • RWTH Aachen University
      • • Institut für Angewandte Medizintechnik
      • • Department of Surgery
      Aachen, North Rhine-Westphalia, Germany
  • 2004–2006
    • Universitätsklinikum Jena
      Jena, Thuringia, Germany