Comparison of risk-scoring systems in the prediction of outcome after liver resection

Background: Risk prediction techniques commonly used in liver surgery include the American Society of Anesthesiologists (ASA) grading, Charlson Comorbidity Index (CCI) and cardiopulmonary exercise tests (CPET). This study compares the utility of these techniques along with the number of segments resected as predictive tools in liver surgery. Methods: A review of a unit database of patients undergoing liver resection between February 2008 and January 2015 was undertaken. Patient demographics, ASA, CCI and CPET variables were recorded along with resection size. Clavien-Dindo grade III–V complications were used as a composite outcome in analyses. Association between predictive variables and outcome was assessed by univariate and multivariate techniques. Results: One hundred and seventy-two resections in 168 patients were identified. Grade III–V complications occurred after 42 (24.4%) liver resections. In univariate analysis of CPET variables, ventilatory equivalents for CO2 (VEqCO2) was associated with outcome. CCI score, but not ASA grade, was also associated with outcome. In multivariate analysis, the odds ratio of developing grade III–V complications for incremental increases in VEqCO2, CCI and number of liver segments resected were 1.09, 1.49 and 2.94, respectively. Conclusions: Of the techniques evaluated, resection size provides the simplest and most discriminating predictor of significant complications following liver surgery

Registration of VLF-sferics at the von-Neumayer Station

A VLF-sferics-analyzer was operating at the German antarctic station von-Neumayer from January to July 1983. This analyzer registrated far distant lightning events in the frequency range between 5 and 9kHz. Assuming the location of these sources to be known, the propagation characteristics of the atmospheric wave guide between the earth and the ionosphere can be derived along the propagation path. The method of measurement is described. The data of June 1983 are evaluated and the distances of the sources are determined from a comparison with rain fall records during the same month and, in addition, from sferics registrations obtained at a second station in Pretoria, South Africa. The main result is that the ionospheric D layer along the propagation paths from the east coast of South America to the von-Neumayer station and from South Africa to the von-Neumayer station do not show a significant daily variation. The virtual ionospheric reflection height is about 82km for VLF waves between 5 and 9kHz during June. This corresponds to night time conditions at northern mid-latitudes in winter