Operative field temperature during transnasal endoscopic cranial base procedures

Background

Data regarding the safety of endoscopic skull base exploration are very scarce. With this method, fragile vital structures (cranial nerves, the optic complex, brainstem, hypothalamus or cerebral ventricles) are exposed to direct illumination within a closed space. Also, high-speed drills, cauterization and ultrasonic aspiration deliver a significant load of thermal energy. The aim of this study was to record the temperature close to the structures of the skull base and in the intradural space during the procedures performed using extended endoscopic transnasal approaches.

Methods

The temperature of the skull base was continuously recorded during six transnasal endoscopic procedures. Implantable copper-constantan thermocouples were inserted: one into the esophagus and another through the nostril to reach the operative field at the skull base.

Results

At the beginning of the procedure, the temperature of the operative field was on average 36.8 °C?±?0.80 °C, i.e. only 1 °C higher than the esophageal temperature. Then it grew continuously during the whole procedure, to eventually reach a level of 42–43 °C at the final stage, whereas the esophageal temperature remained stable. Occasionally, the temperature increased up to 45 °C during cauterization and ultrasonic aspiration, and even up to 62 °C during high-speed drilling.

Conclusion

Endoscopic skull base surgery is associated with an incessant increase of the temperature of the intraoperative field. The temperature can peak suddenly to levels which can potentially harm neural structures and influence the rate of postoperative complications.     

When can it be not optimal to adopt a new technology? A viability theory solution to a two‐stage optimal control problem of new technology adoption

Politicians often deplore economic agents’ behaviour when they do not accept new technologies. For a new technology to be adopted, the new technology value function needs to dominate the old technology value function. If this is the case, a technology switch will occur. We characterise the value functions, without computing them, using the fact that their hypographs are viability kernels of some auxiliary control problems and study whether the graphs intersect. If they do not, the corresponding value functions do not dominate each other, and the switch cannot occur at a positive time. Using this characterisation, we analyse a technology adoption problem and show how to recognise the models, for which the switch will occur at time zero or never, without solving an optimal control problem. We conclude that the current control regime may not change if the economic agents’ preferences are modelled as an integral of discounted differences between a reward from the flow variable (control) and a penalty from the stock variable (state).Copyright © 2011 John Wiley & Sons, Ltd.     

The risk of atherosclerosis in patients with chronic kidney disease

Background

Chronic kidney disease (CKD) is becoming a serious health problem; the number of people with impaired renal function is rapidly rising, especially in industrialized countries. A major complication of CKD is cardiovascular disease. Accelerated atherosclerosis has been observed in early stages of renal dysfunction. The purpose of this study was to examine the relationship between the degree of renal insufficiency and both the prevalence and intensity of coronary artery disease (assessed on the basis of number of vessels with stenosis).

Methods

446 individuals with both serum creatinine >120 μmol/l (men) or >96 μmol/l (women) and acute coronary syndrome were included in the study. All patients included in this analysis underwent urgent coronarography. Data concerning glomerular filtration rate (GFR), number of vessels with stenosis, hypertension, lipid disorders, creatinine concentration, C-reactive protein, glucose and lipid profile were analyzed.

Results

This study confirmed that moderate to severe renal impairment is associated with accelerated atherosclerosis. Moreover, patients with GFR values below 60 ml/min/1.73 m² are predisposed to accelerated, multivessel cardiovascular disease.

Conclusions

GFR seems to be an independent risk factor for multivessel cardiovascular disease. Due to the fact that patients with renal dysfunction are at high risk of cardiovascular events, they should obtain optimal treatment resulting not only in kidney protection but also in the elimination of cardiovascular risk factors.     

Bone graft incorporation after revision hip arthroplasty in patients with rheumatoid arthritis, seventy eight revisions using bone allografts with or without metal reinforcements

Purpose

The aim of the study was to assess bone graft incorporation after revision hip arthroplasty in patients with rheumatoid arthritis (RA).

Methods

We report an acetabular reconstruction using impacted, morselized, frozen, radiation sterilized bone allografts in 71 patients suffering from RA. There were sixty-six women and five men at a mean age of 57.5 years. Reconstruction was performed in 78 revision total hip arthroplasties (THAs) for aseptic loosening of acetabular component. The mean follow-up was five years and four months. In 38 cases, a revision was done with use of reinforcement devices.

Results

In four revised hips (10 %) without reinforcement implants, resorption of the allografts was noticed. All Mueller rings and 50 % of unscrews cages (Link, Howmedica) were revised because of aseptic loosening and bone graft resorption. In all of 17 hips with the Burch-Schneider cage, no measurable migration or bone allografts resorption occurred. There were no major general complications.

Conclusions

Acetabular reconstruction with use of morselized, frozen, radiation sterilized bone allografts and the Burch-Schneider cage can be highly successful in managing massive deficiency of acetabular bone stock in revision hip arthroplasty in RA patients.     

Experience with intraoperative high frequency Doppler sonography in neurosurgical practice

Abstract

The method of blood flow velocity (BFV) evaluation by intraoperative application of the high frequency Doppler is presented. The device is used to estimate BFV changes in small caliber arteries by direct placement of the probe upon the examined vessel. BFVexaminations were performed on the site during aneurysm operations, during transsphenoidal approaches to identify the intracavernous portion of leA embedded in the tumor mass and in patients after encephalodurosynangiosis evaluated on the outpatient basis. Technical characteristics of the flowmeter used are described and examples of the BFV pictures in cerebral arteries are presented. The device allows a precise BFVevaluation in the selected vessel and detection of changes in BFV patterns particularly useful during aneurysms surgery. This method of identifying cerebral vessels may become applicable in other types of neurosurgical operations. [Neural Res 1998; 20: 655–657]     

Impact and persistence of cirrhotic cardiomyopathy after liver transplantation

Cirrhotic cardiomyopathy causes variable degree of systolic and diastolic dysfunction (DD) and conduction abnormalities. The primary aim of our study was to determine whether pre‐transplant DD and prolonged corrected QT (QTc) predict a composite of mortality, graft failure, and major cardiovascular events after liver transplantation. We also evaluated the reversibility of cirrhotic cardiomyopathy after transplantation. Adult patients who underwent liver transplantation at our institution from January 2007 to March 2009 were included. Data were obtained from institutional registry, medical record review, and evaluation of echocardiographic images. Among 243 patients, 113 (46.5%) had grade 1 DD, 16 (6.6%) had grade 2 DD, and none had grade 3 DD. The mean pre‐transplant QTc was 453 milliseconds. After a mean post‐transplant follow‐up of 5.2 years, 75 (31%) patients satisfied the primary composite outcome. Cox regression analysis did not show any significant association between DD and the composite outcome (P=.17). However, longer QTc was independently associated with the composite outcome (HR: 1.01, 95% confidence interval: 1.00–1.02, P=.05). DD (P<.001) and left ventricular mass index (P=.001) worsened after transplantation. In conclusion, QTc prolongation appears to be associated with worse outcomes. Although DD did not impact outcomes, it significantly worsened after transplantation.     

Anti-tumor action of tumor necrosis factor against Bomirski Ab melanoma in hamsters

Introduction: Tumor necrosis factor (TNF) is a cytokine able to exert anti-tumor activity in various models and modes of applications. However, the exact mechanism mediating the in vivo anti-tumor effect of TNF has not yet been clarified. Materials and Methods: The effects of intratumoral injection of rat TNF into hamsters bearing Bomirski Ab amelanotic melanoma, a fast growing tumor of high metastatic potential, were tested. Subcutaneous injections of the anti-angiogenic compound TNP-470 allowed analysis of its influence on the effects of TNF administration. Results: TNF application resulted in a significant inhibition of tumor growth and changes in metastasis pattern. Accelerated hemorrhagic necrosis was also observed, indicating the effect of the cytokine on tumor vessels. Moreover, the synergistic anti-tumor effect of TNF and anti-angiogenic agent TNP-470 suggested a cooperative activity of both substances on tumor vasculature. Microscopically, the effect of TNF injections was expressed by an increase in the amount of tumor cells with nuclear pyknosis and karryorrhexis. In vitro assays indicated a direct cytotoxic effect of TNF against Ab melanoma cells, most probably as an outcome of apoptosis. Intratumoral application of TNF also caused some modulation of cytokine response in melanoma-bearing hamsters as evidenced by increased levels of IL-6 in blood serum. Conclusions: This study established Bomirski Ab melanoma as a useful model for complex analysis of the anti-tumor activity of TNF.     

Evaluation of selected parameters of the antioxidative system in patients with type 2 diabetes in different periods of metabolic compensation

Introduction: The aim of the study was to evaluate some selected parameters of the antioxidative system in patients with type 2 diabetes. Materials and Methods: Eighty-one type 2 diabetes patients took part in the study (39 patients with metabolically balanced and 42 with metabolically unbalanced diabetes). The control group consisted of 30 healthy people. The total antioxidant capacity of plasma was measured fluorometrically using phycoerythrin. To calculate the low-molecular-weight antioxidant concentration in the plasma samples, the duration of Trolox activity as a function of its concentration in the sample was measured. The activity of antioxidative enzymes in red blood cells was determined using the Misra and Fridovich method and Beers and Sizer method. Results: The total plasma antioxidant capacity and the low-molecular-weight antioxidant concentration in the group of patients with metabolically compensated type 2 diabetes were statistically significantly higher than in the group of patients with metabolically uncontrolled diabetes. The activity of antioxidative enzymes was found to be higher in the group of type 2 diabetes patients at the stage of metabolic balance. Conclusions: The obtained results confirm the thesis of glucose toxicity and intensification of oxidative stress in patients with diabetes.