Heart Rate Variability Predicts Severe Hypotension after Spinal Anesthesia

Background: Hypotension due to vasodilatation after spinal anesthesia (SA) may be harmful. Heart rate variability, an indirect measure of autonomic control, may predict hypotension.

Methods: One hundred patients were studied. Retrospectively, heart rate variability was analyzed in 30 patients, classified depending on the lowest systolic blood pressure (SBP) after SA. Seventy patients were studied prospectively, assigned to one of two groups by their low to high frequency ratio (LF/HF) before SA. Sensitivity and specificity of LF/HF for prediction of decrease of SBP greater 20% of baseline were tested.

Results: Retrospective analysis showed differences of LF/HF depending on the degree of hypotension after SA. Prospective analysis demonstrated significant differences of SBP after SA depending on baseline LF/HF (mean +/- SD): low LF/HF (1.3 +/- 0.7) = > SBP: 91 +/- 8% of baseline versus high LF/HF (5.5 +/- 2.4) = > SBP: 66 +/- 10% of baseline (P < 0.05). Baseline LF/HF as well as high frequency and proportional decrease of SBP after SA correlated significantly, in contrast to baseline hemodynamic parameters heart rate and SBP. A receiver operator curve characteristic analysis showed a sensitivity and specificity of LF/HF > 2.5 of 85% to predict SBP decrease of greater than 20% of baseline after SA.     

Cannabis and driving: A new perspective

Cannabis and driving is an emerging injury‐prevention concern. The incidence of driving while affected by cannabis is rising in parallel with increased cannabis use in the community. Younger drivers are at particular risk. Improvements in research methodology, technology and laboratory testing methods have occurred in the last 10 years. These cast doubt on earlier results and conclusions. Studies now show that cannabis has a significant impairing effect on driving when used alone and that this effect is exaggerated when combined with alcohol. Of particular concern is the presence of cannabis as the sole psychoactive drug in an increasing number of road fatalities and the lack of any structural response to this problem. A review of testing methods, laboratory and real driving studies, and recent epidemiological studies is presented. Suggestions for methods of further data collection and future public policy are made.     

The effect of pressurized carbon dioxide as a temporary plasticizer and foaming agent on the hot stage extrusion process and extrudate properties of solid dispersions of itraconazole with PVP-VA 64.

The aim of the current research project was to explore the possibilities of combining pressurized carbon dioxide with hot stage extrusion during manufacturing of solid dispersions of itraconazole and polyvinylpyrrolidone-co-vinyl acetate 64 (PVP-VA 64) and to evaluate the ability of the pressurized gas to act as a temporary plasticizer as well as to produce a foamed extrudate. Pressurized carbon dioxide was injected into a Leistritz Micro 18 intermeshing co-rotating twin-screw melt extruder using an ISCO 260D syringe pump. The physicochemical characteristics of the extrudates with and without injection of carbon dioxide were evaluated with reference to the morphology of the solid dispersion and dissolution behaviour and particle properties. Carbon dioxide acted as plasticizer for itraconazole/PVP-VA 64, reducing the processing temperature during the hot stage extrusion process. Amorphous dispersions were obtained and the solid dispersion was not influenced by the carbon dioxide. Release of itraconazole from the solid dispersion could be controlled as a function of processing temperature and pressure. The macroscopic morphology changed to a foam-like structure due to expansion of the carbon dioxide at the extrusion die. This resulted in increased specific surface area, porosity, hygroscopicity and improved milling efficiency.     

Differential Effects of Anesthetics on Mitochondrial KATP Channel Activity and Cardiomyocyte Protection

Background: Mitochondrial adenosine triphosphate-sensitive potassium (mitoKATP) channels play a pivotal role in mediating cardiac preconditioning. The effects of intravenous anesthetics on this protective channel have not been investigated so far, but would be of importance with respect to experimental as well as clinical medicine.

Methods: Live cell microscopy was used to visualize and measure autofluorescence of flavoproteins, a direct reporter of mitoKATP channel activity, in response to the direct and highly selective mitoKATP channel opener diazoxide, or to diazoxide following exposure to various anesthetics commonly used in experimental and clinical medicine. A cellular model of ischemia with subsequent hypoosmolar trypan blue staining served to substantiate the effects of the anesthetics on mitoKATP channels with respect to myocyte viability.

Results: Diazoxide-induced mitoKATP channel opening was significantly inhibited by the anesthetics R-ketamine, and the barbiturates thiopental and pentobarbital. Conversely, urethane, 2,2,2-trichloroethanol (main metabolite of [alpha]-chloralose and chloral hydrate), and the opioid fentanyl potentiated the channel-opening effect of diazoxide, which was abrogated by coadministration of chelerythrine, a specific protein kinase C inhibitor. S-ketamine, propofol, xylazine, midazolam, and etomidate did not affect mitoKATP channel activity. The significance of these modulatory effects of the anesthetics on mitoKATP channel activity was substantiated in a cellular model of simulated ischemia, where diazoxide-induced cell protection was mitigated by R-ketamine and the barbiturates, while urethane, 2,2,2-trichloroethanol, and fentanyl potentiated myocyte protection.     

Aktualisierte Kurzfassung der Leitlinien zur Pr?vention, Diagnostik und Therapie der nosokomial erworbenen Pneumonie

Hintergrund:  

Die nosokomiale Pneumonie gehört zu den häufigsten nosokomialen Infektionen und ist die häufigste auf der Intensivstation. Die nosokomiale Pneumonie ist mit einer signifikanten Mortalität und Morbidität assoziiert, und ihr Auftreten verschlechtert die Prognose des Patienten deutlich. Nach der Definition der DRGs auch im deutschen Krankenhaussystem ist die nosokomiale Pneumonie überwiegend Sache des Krankenhauses und kann somit nicht nur das Ergebnis der Patientenbehandlung, sondern auch das finanzielle Ergebnis des Krankenhauses beeinträchtigen.     

Endocrine evaluation after endoscopic third ventriculostomy (ETV) in children

Objective Endoscopic third ventriculostomy (ETV) is a standard procedure for the treatment of obstructive hydrocephalus in children. Main part of the procedure is the perforation of the third ventricle floor (tuber cinereum). This structure is part of the hypothalamic–pituitary neuronal network of cerebral endocrine regulation. There are no systematic data available about the endocrine status after ETV in children. Materials and methods We examined 20 children who had undergone ETV. Examination included laboratory tests (adrenocorticotropic hormone, prolactin, insulin-like growth factor 1 [IGF-1], IGF-binding protein 3 [IGFBP-3], fT3, fT4, thyroid-stimulating hormone [TSH], serum osmolarity, electrolytes, glucose, urea, follicle-stimulating hormone [FSH] and luteinizing hormone [LH], and testosterone in selected patients), measurement of weight, height, and head circumference, and physical examination. The study was approved by the Ethics Committee of the Medical Faculty of Kiel University. Results In seven patients, prolactin was moderately elevated. One patient demonstrated a significantly increased prolactin (56.3 ng/ml). In all eight patients, this was the only laboratory value that was out of the normal range; all other parameters were normal. Three other patients showed one abnormal parameter (decrease in FSH and LH, increase in TSH, decrease in IGF-1 and IGFBP-3). In nine patients, weight or height was not within the 3rd to 97th centiles for age. Discussion and conclusion More patients than expected demonstrated endocrine laboratory abnormalities. However, there was no clinical relevance in any of the studied patients. It remains inconclusive whether ETV contributes to the abnormalities of prolactin levels or to other endocrine parameters in pediatric patients. Longitudinal studies are necessary to delineate the effect of ETV on endocrine regulation. Presented at the Third World Conference of the International Study Group on Neuroendoscopy (ISGNE), Marburg, Germany, 15–18 June 2005.