Developing reference material for validation of hair spectral analysis reliability

Mineral analysis of human hair is increasingly proposed as a estimation method for the human contamination with environmental mineral pollutants and even as a diagnostic tool for related health problems. It offers a good way of investigating long-term variation in trace element concentration. Many minor and trace elements can be determined in hair samples with good precision and sensitivity by a variety of analytical techniques. An important requirement in such work is the application of suitable analytical quality control, for which the availability of a hair reference material is important. In paper the preparation of the human hair reference material and the initial stages which were taken to confirm its certification are described

Accuracy of cardiac output measurements with pulse contour analysis (PulseCO (TM)) and Doppler echocardiography during off-pump coronary artery bypass grafting

Background and objective: During off-pump coronary bypass grafting, surgical manipulation and dislocation of the heart may cause cardiovascular instability. Monitoring of cardiac output facilitates intraoperative haemodynamic management but pulmonary artery catheters are often considered too invasive. Pulse contour analysis and transoesophageal echocardiography could serve as alternatives, but there is controversy about their accuracies. We validated pulse contour analysis using a standard radial arterial catheter (PulseCO(TM)) and aortic Doppler flowmetry with transoesophageal echocardiography in patients undergoing off-pump coronary bypass surgery. Pulmonary arterial thermodilution served as the reference technique. Methods: In 20 patients undergoing off-pump coronary bypass, cardiac output was measured with bolus thermodilution (COTD), pulse contour analysis (COPC), and transoesophageal echocardiography (COecho) at fixed time intervals during the procedure. Data were compared using linear regression and Bland-Altman analysis. At the end of the procedure, dobutamine was infused at a rate of 2.5 mu g kg(-1) min(-1) in six patients to study the agreement between methods in quantifying changes in cardiac output. Results: Comparison between COPC and COTD showed a bias +/- limits of agreement of -0.03 +/- 1.30 Lmin(-1) (mean error 29%). Doppler echocardiography was not always feasible when the heart was displaced from the oesophagus and had lower accuracy: bias +/- limits of agreement vs. COTD was 0.45 +/- 1.93 (mean error 43%. Increases in cardiac output induced by dobutamine were well quantified both by pulse contour analysis (COPC = 0.76 X COTD + 0.58; r(2) = 0.65) and Doppler although the latter tended to overestimate these changes (COecho = 1.5 8 X COTD -0.13; r(2) = 0.53). Conclusions: Calibrated pulse contour analysis using the PulseCO system is an acceptable technique to measure cardiac output non-invasively in off-pump coronary bypass patients. Doppler echocardiography performs less well and is not always feasible with transoesophageal echocardiography when the heart is displaced

Differential effects of lumbar and thoracic epidural anaesthesia on the haemodynamic response to acute right ventricular pressure overload

The safety of epidural anaesthesia in patients at risk for right ventricular pressure overload remains controversial. We compared the haemodynamic effects of vascular and cardiac autonomic nerve block, induced by selective lumbar (LEA) and high thoracic epidural anaesthesia (TEA), respectively, in an animal model subjected to controlled acute right ventricular pressure overload. Eighteen pigs were instrumented with epidural catheters at the thoracic (T) and lumbar (L) level and received separate injections at T2 (1 ml) and L3 (4 ml) with saline (s) or bupivacaine 0.5% (b). Three groups of six animals were studied: (i) a control group (Ls+Ts), (ii) LEA group (Lb+Ts), and (iii) TEA group (Ls+Tb). Haemodynamic measurements including biventricular pressure-volumetry were performed. Right ventricular afterload was then increased by inflating a pulmonary artery (PA) balloon. Measurements were repeated after 30 min of sustained right ventricular afterload increase. LEA decreased systemic vascular resistance (SVR) and did not affect ventricular function. TEA had minor effects on SVR but decreased left ventricular contractility while baseline right ventricular function was not affected. Control and LEA-treated animals responded similarly to a PA balloon occlusion with an increase in right ventricular contractility and heart rate. Animals pretreated with a TEA did not show this positive inotropic response and developed low cardiac output in the presence of right ventricular pressure overload. In contrast to LEA, TEA reduced the haemodynamic tolerance to PA balloon occlusion by inhibiting the right ventricular positive inotropic response to acute pressure overload

There is an absence of scientific authority over research assessment as a professional practice, leaving a gap that has been filled by database providers

Research metrics have become more established as a means to assess research performance. This is understandable given research institutions' and funders' demand for assessment techniques that are relatively cheap and universally applicable, even though use of such metrics remains strongly contested within scientific communities. But to what extent does the academic research field of evaluative citation analysis confer legitimacy to research assessment as a professional practice? Arlette Jappe, David Pithan and Thomas Heinze find that the growth in the volume of ECA publications has not led to the formation of an intellectual field with strong reputational control. This has left a gap which has been filled by commercial database providers, who by selecting and distributing research metrics have gained a powerful role in defining standards of research excellence without being challenged by expert authority