Evaluating an optimal gastric closure method for transgastric surgery

Background The transgastric approach is currently being studied as a potentially less invasive alternative to conventional laparoscopy for intra-abdominal surgery. A major obstacle to overcome is the closure of the transgastric incision in a rapid, reproducible, and safe manner. The effectiveness of various techniques for gastrotomy closure were compared by assessing leak pressures in an ex vivo porcine stomach model. Methods Whole stomachs from adult white pigs were suspended in a Plexiglas box to facilitate endoscopic technique. Standard gastrotomies were made by needle knife incision and dilation with a controlled radial expansion (CRE) balloon. The first arm used standard QuickClips™; the second, a prototype device developed by LSI Solutions; the third, hand-sewn by a senior surgeon; the final, a control with open gastrotomy. Five stomachs were tested per study arm. After closure, each stomach was inflated by an automated pressure gauge. The pressures to achieve air leakage and liquid leakage were recorded. Results The unclosed controls demonstrated air leakage at a median pressure of 15 mmHg, representing baseline system resistance. The QuickClip closures leaked air at a median pressure of 33 mmHg. The prototype gastrotomy device yielded the highest median air leak pressure of 85 mmHg while dramatically diminishing time for incision and gastrotomy closure to approximately 5 min. The hand-sewn closures leaked air at a median pressure of 47 mmHg. Using Kruskal-Wallis statistical analysis, the comparisons were significant (p = 0.0019). Post hoc paired comparisons using MULTTEST procedure with both Bonferroni and bootstrap adjustments revealed that the difference between prototype and clips was significant; prototype versus hand-sewn was not. Liquid-leak pressures produced similar results. Conclusions The prototype device decreases procedure time and yields leak-resistant gastrotomy closures that are superior to clips and rival hand-sewn interrupted stitches. An erratum to this article can be found at     

Intramuscular Injection of Sevoflurane Detects Malignant Hyperthermia Predisposition in Susceptible Pigs

Background: The authors hypothesized that intramuscular sevoflurane injection allows diagnostic differentiation between malignant hyperthermia-susceptible (MHS) and -nonsusceptible (MHN) pigs by measurement of intramuscular lactate and carbon dioxide partial pressure (Pco2), and that dantrolene reduces the sevoflurane-induced Pco2 increase.

Methods: With approval of the local animal care committee, microdialysis probes with attached microtubing for sevoflurane injection were placed in the adductor muscles of nine MHS and six MHN pigs, and Pco2 probes with microtubing were positioned in the triceps muscle of eight MHS and six MHN pigs. After equilibration, sevoflurane boluses at different concentrations and a sevoflurane-dantrolene bolus were injected synchronously. Lactate, pyruvate, and glucose as well as Pco2 were measured spectrophotometrically, and the rate of Pco2 increase was calculated.

Results: Intramuscular sevoflurane injection increased local lactate and Pco2 dose dependently, and significantly higher in MHS than in MHN pigs. Measurement of the rate of Pco2 increase allowed a distinct differentiation between single MHS and MHN pigs. No significant increase in Pco2 was found with sevoflurane and dantrolene.     

Temporo-spatial distribution of blood vessels in human lumbar intervertebral discs

While there is consensus in the literature that blood vessels are confined to the outer anulus fibrosus of normal adult intervertebral disc, debate continues whether there is a vascular in-growths into inner parts of the intervertebral disc during degeneration. We therefore tested the hypothesis that vascular in-growth is not a distinct feature of disc degeneration. The specific endothelial cell marker CD 31 (PECAM) was used to immunohistochemically investigate 42 paraffin-embedded complete mid-sagittal human intervertebral disc sections of various ages (0–86 years) and varying extent of histomorphological degeneration. Additionally, 20 surgical disc samples from individuals (26–69 years) were included in this study. In discs of fetal to infantile age, blood vessels perforated the cartilaginous end plate and extended into the inner and outer anulus fibrosus, but not into the nucleus pulposus. In adolescents and adults, no blood vessels were seen except for the outer zone of the anulus fibrosus adjacent to the insertion to ligaments. The cartilaginous end plate remained free of vessels, except for areas with circumscribed destruction of the end plate. In advanced disc degeneration, no vessels were observed except for those few cases with complete, scar-like disc destruction. However, some rim lesions and occasionally major clefts were surrounded by a small network of capillary blood vessels extending into deeper zones of the anulus fibrosus. A subsequent morphometric analysis, revealed slightly “deeper” blood vessel extension in juvenile/adolescent discs when compared to young, mature and senile adult individuals with significantly “deeper” extension in the posterior than anterior anulus. The analysis of the surgical specimens showed that only sparse capillary blood vessels which did not extend into the nucleus pulposus even in major disc disruption. Our results show that vascular invasion deeper than the periphery was not observed during disc degeneration, which supports the hypothesis that vascular in-growth is not a distinct feature of disc degeneration. This study was supported by a grant from the AO/ASIF Foundation Switzerland (00-B72) and a grant from the AO Spine (SRN 02/103).     

Biological treatment strategies for disc degeneration: potentials and shortcomings

Recent advances in molecular biology, cell biology and material sciences have opened a new emerging field of techniques for the treatment of musculoskeletal disorders. These new treatment modalities aim for biological repair of the affected tissues by introducing cell-based tissue replacements, genetic modifications of resident cells or a combination thereof. So far, these techniques have been successfully applied to various tissues such as bone and cartilage. However, application of these treatment modalities to cure intervertebral disc degeneration is in its very early stages and mostly limited to experimental studies in vitro or in animal studies. We will discuss the potential and possible shortcomings of current approaches to biologically cure disc degeneration by gene therapy or tissue engineering. Despite the increasing number of studies examining the therapeutic potential of biological treatment strategies, a practicable solution to routinely cure disc degeneration might not be available in the near future. However, knowledge gained from these attempts might be applied in a foreseeable future to cure the low back pain that often accompanies disc degeneration and therefore be beneficial for the patient. This study was supported by a grant from the AO Spine (SRN 02/103).     

CD4+CD25+FoxP3+ T lymphocytes fail to suppress myelin basic protein-induced proliferation in patients with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disorder directed against self antigens of the central nervous system. CD4⁺CD25⁺FoxP3⁺ regulatory T cell (T_reg) mediated suppression is an essential mechanism of self-tolerance. We studied whether changes in the suppressive function of a mixture of CD25^high and CD25^intemediate expressing T_reg cells in myelin basic protein (MBP)-induced proliferation occurred in untreated MS patients. Suppression of MBP-induced proliferation was observed in 13 out of 29 (45%) MS patients; this was significantly (p < 0.05) less compared with 17 out of 19 (89%) healthy individuals. Relative T_reg counts was significantly increased in MS patients (mean ± S.D.; 20 ± 8%) compared with healthy individuals (15 ± 5%). These findings suggest that impaired T_reg function may be involved in pathogenesis of MS.     

Risk of graft fracture after dorso-ventral thoraco-lumbar spondylodesis: is there a correlation with graft size?

Study design

Retrospective clinical study in patients with dorso-ventral thoraco-lumbar spondylodesis.

Objective

To investigate whether the ratio between graft cross sectional area and the surface area of the adjacent endplates has any effect on the midterm stability of the spondylodesis.

Summary of background data

Dorso-ventral spondylodesis in the region of the thoraco-lumbar spine is one of the most frequent operations in orthopaedic surgery. Anterior stabilization with autologous iliac crest graft currently is a standard approach in many hospitals. Although numerous recommendations are given how to perform this technique, no clinical advice is available with regard to minimum graft size.

Methods

Sixty-four-slice CT-scans were obtained from 82 patients 4–12 months after posterior spondylodesis with anterior implantation of iliac crest graft and stabilization with an internal fixator. The scans were analyzed using image analysis software. First, the cross sectional area of the graft was calculated and then the surface area of the adjacent endplates. The ratio between graft cross sectional area and endplate surface area was then calculated from these two values. The grafts were then evaluated in sagittal reconstruction for signs of fracture.

Results

The probability for graft fracture in autologous tricortical grafts was >0.1% (p < 0.001) if the graft cross sectional area exceeded 23.9% of the surface area of the adjacent endplates. Patients with lower ratio values had a higher fracture risk and below a value of 10% all grafts fractured.

Conclusion

The relationship between graft cross sectional area and adjacent endplate area has an important effect on graft midterm stability in ventral spondylodesis of the thoraco-lumbar spine. In our opinion, the risk of graft fractures in dorso-ventral spondylodesis can be reduced by implantation of an appropriately sized graft without any additional procedures or instrumentation.     

F-18 Fluorodeoxyglucose (FDG) and C-Reactive Protein (CRP)

This study was done to evaluate if the accuracy of FDG-PET concerning the differentiation of benign and malignant pancreatic masses differs for patients with and without elevated C-Reactive Protein (CRP). Three hundred-four patients (165 neoplasms, 98 chronic pancreatitis, and 41 benign lesions) received FDG-PET of the abdomen prior to planned resective surgery. CRP was unknown, normal, and elevated with 211, 71, and 22 patients, respectively. For differentiation of benign and malignant lesions, specificity was 87% for patients with unknown or normal CRP, and it was 40% for patients with elevated CRP (P < 0.01). Thirty-five percent of those patients with both a positive PET and elevated CRP were false positive. On the contrary, sensitivity was slightly higher in the group with elevated CRP (92% vs. 80%, NS). FDG-PET is a sensitive and specific test for patients with normal CRP, however, FDG-PET may be false positive if CRP is elevated. Proper patient selection is therefore important. CRP or other parameters indicative of active inflammation appear useful adjuncts for the interpretation of increased FDG-accumulation.     

Ultrasonography of malignant breast neoplasms. Analysis of carcinomas missed as tumor.

PURPOSE: To analyze the malignant breast neoplasms missed as tumor on ultrasonography (US). MATERIAL AND METHODS: A total of 355 malignant tumors were confirmed at histology among 2,985 consecutive patients who underwent breast US. There were no prospectively recorded mammographic findings in 28 of the 355 tumors. The remaining 327 tumors included 16 ductal carcinomas in situ (DCIS) and 66 invasive carcinomas with suspicious microcalcifications on mammography. Excluding these 82 tumors because US would not have been indicated using strict criteria, a subpopulation of 245 noncalcified invasive malignant tumors remained for analysis. The neoplasms missed as tumor on US were analyzed for the whole tumor group (n=355) and the subpopulation (n=245). RESULTS: 42 (11.8%) of the 355 malignant neoplasms were missed as tumor on US, including 6 (2.5%) of the 243 palpable and 36 (32.1%) of the 1 12 nonpalpable malignancies. Most of the missed tumors were DCIS and microinvasive ductal carcinomas dominated by DCIS. In the subpopulation, 14 (5.7%) of the 245 malignancies were missed as tumor on US, including 4 (2.2%) of the 180 palpable and 10 (15.4%) of the 65 nonpalpable lesions. Of the 245 malignancies, 6 (2.4%) had a normal US finding, including 2 palpable retropapillary tumors and 4 incidental findings at histology. CONCLUSION: Using strict criteria for performing US as an adjunct to mammography, by far the most malignant breast neoplasms are diagnosed as a tumor on US.     

Aspirin in coronary artery bypass surgery: new aspects of and alternatives for an old antithrombotic agent.

The success of coronary artery bypass graft surgery (CABG) depends mainly on the patency of the graft vessels. Aortocoronary vein graft disease is comprised of three distinct but interrelated pathological processes: thrombosis, intimal hyperplasia and atherosclerosis. Early thrombosis is a major cause of vein graft attrition during the first month after CABG, while during the remainder of the first year, intimal hyperplasia forms a template for subsequent atherogenesis, which thereafter predominates. Platelets play a crucial role in the pathophysiology of graft thrombosis and aspirin is the primary antiplatelet drug that has been shown to improve vein graft patency within the first year after CABG. Nevertheless, a significant number of grafts still occlude in the early postoperative period despite 'appropriate' aspirin treatment. Moreover, laboratory investigations showed that the expected inhibition of platelet function is not always achieved. This has been called 'aspirin nonresponse' or 'aspirin resistance', although a uniform definition is lacking. The finding that a considerable number of patients show an impaired antiplatelet effect of aspirin after CABG brought new insight into the discussion concerning poor patency rates of bypass grafts: the early period after CABG shows a coincidence of an increased risk for bypass thrombosis (amongst others, due to platelet activation and endothelial cell disruption of the graft) and an increased prevalence of aspirin resistance. Hitherto, the underlying mechanisms of aspirin resistance are uncertain and largely hypothetical; amongst others, increased platelet turnover, enhanced platelet reactivity, systemic inflammation, and drug-drug interaction are discussed. Up to now available data concerning the clinical outcome of aspirin resistant CABG patients are limited, and there is evidence that platelets of patients with graft thrombosis are more likely to be resistant to aspirin compared with patients without thrombotic events. Many publications concerning aspirin resistance are available today, but reports addressing this topic in CABG patients are sparse. This review summarises recent insights into the antiplatelet treatment after CABG and describes the clinical benefit, but also the therapeutic failure of the well-established drug aspirin. Moreover, possible pharmacological approaches to improve antithrombotic therapy in aspirin nonresponders among CABG patients are discussed.     

Vascular renal anatomy and the ureteropelvic junction: preoperative multidetector CT scanning with split-bolus injection as a predictor of laparoscopic findings

PURPOSE: To compare multidetector CT scan (MDCT) results with intraoperative findings in the detection of an inferior-pole pedicle crossing the ureteropelvic junction. PATIENTS AND METHODS: Over the 2-year study period, 35 patients receiving laparoscopic pyeloplasty underwent preoperative investigation with a novel MDCT protocol in order to detect crossing vessels. Postprocessing, including maximum intensity projection, volume-rendering technique, and multiplanar reconstruction, was used in addition to standard axial views. RESULTS: All the arteries found during laparoscopic surgery were detected by MDCT, but one radiologic false-positive was noted at the beginning of the series. Seven veins were not detected with MDCT. In the only case featuring an isolated inferior-pole vein, the aberrant vessel was identified by MDCT. CONCLUSION: Multidetector CT scanning is a highly accurate way of providing all the information necessary preoperatively concerning renal parenchymal anomalies, urinary stones, and collecting system and vessel anatomy. It helps physicians make appropriate therapeutic decisions and gives surgeons information about what they can expect during laparoscopic procedures.