A new glucose sensor for use in whole blood.

Existing electrochemical glucose sensors are either single use sensors produced in mass fabrication technologies or rather big sensors for multiple use with membranes to be changed frequently. Single use means no sensor maintenance but has the disadvantage that quality control measurements cannot be done with the same sensor used for the sample. Generally also the cost per test is relatively high. Multiple use sensors give the possibility of closer quality control and they are generally cheaper than the single use sensors for higher sample frequency but have the disadvantage of frequent need of remembraning. This often means special training and is a health risk due to sensor contamination by biological fluids. We combined the advantages of both principles meaning that we developed a new glucose sensor for multiple use in an essentially planar technology - thus being able to be produced very cheap. The underlying basic working principle is using glucose oxidase and detecting hydrogen peroxide. Due to the carbon base of the sensor it has a large surface area and therefore a very high sensitivity (microamps range at biological glucose concentrations) although the sensor itself is very small needing only about 10 microL of sample. The sensor shows a linear range of up to 40 mmol/L, a life time in use of far more than 1000 human serum samples and correlation coefficients between plasma and whole blood of r = 0.99. Interferences are well within clinical acceptability. Thus we conclude that this sensor works well in undiluted human body fluids and due to the very cheap production processes the whole sensor can be exchanged when it is old thus eliminating any need for remembraning or special maintenance.

More on the measurement of ionized magnesium in whole blood.

Current technology has made it possible to measure ionized magnesium with user-friendly ion selective electrode technology. Although this technology has not reached a perfect status literature shows that it can be used in clinical routine especially in serum. This paper deals with issues concerning the measurement of ionized magnesium in whole blood. To measure in whole blood apart from an instrument with good general performance data an adequate sample treatment is especially critical. We tested a number of different sample containers and found that they interfere in different degrees with the magnesium determination. In some cases this is due to silicone giving falsely high ionized magnesium values which may be twice the real value and even higher. Another problem is the heparinization of the sample. We found that different heparins may alter the result in a different way. The well known complexing capability of heparin may lead to a reduction of the ionized magnesium within the sample and thus to false low results. But some heparins cause elevated results. The reason for this may be zinc. Test procedures to check the quality of anticoagulants are given. Due to these procedures sample containers could be found which do not interfere with the determination of ionized magnesium in whole blood - thus making the measurement possible. All these factors indicate that the measurement of ionized magnesium really needs a very well defined sample handling - otherwise false results may arise. This is not only true for the measurement of whole blood but also for plasma or even for "so called serum" as there might be a sample container within the chain from patient to the instrument which is unsuitable- and thus will alter the result.

The effect of Bepridil on respiratory and cardiovascular function: a placebo-controlled study.

Bepridil is a novel substance with antianginal and specific antiarrhythmic activities. To investigate its effect on bronchomotor and cardiovascular function a placebo-controlled, randomized, double-blind study was performed in 12 healthy volunteers of both sexes. The test preparations were administered by intravenous infusion. Bepridil was given in a dose of 2 mg/kg, which is sufficient to produce a therapeutic plasma level. With body plethysmography the airway resistance was determined before and 110 min after test drug administration. Oscillatory resistance (Oscillation method, Siregnost FD5, Siemens), blood pressure, and electrocardiogram were recorded before administration of the test preparation and thereafter in short intervals for 20 min and in longer intervals for 2 h. Analysis of the data does not indicate that Bepridil affects respiratory function in other ways than a placebo. Hence Bepridil in therapeutic doses is unlikely to produce untoward effects on the respiratory system. Likewise no unwanted effects on the cardiovascular system were recorded; the observed antitachydardia effect is of therapeutic value. The usefulness of the oscillation method to investigate influences on bronchomotor function has been confirmed.

[The calculation of the oxygen saturation as function of pO2, pH, temperature and base deviation (author's transl)]. / Die Berechnung der Sauerstoffsättigung als Funktion von PO2, pH, Temperatur und Basenabweichung

The paper describes a mathematical relationship between the partial pressure of oxygen and the oxygen saturation of the blood which approximates the standard oxygen dissociation curve. This approximation is based on a consideration of the electro-chemical equilibria of the reduced and the oxygenated blood.