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Electrochemical impedance spectroscopy at CGS Sensors

Measurement technology is EIS = Electrochemical Impedance Spectroscopy, a mature physical method to measure with an electromagnetic field of varying frequencies in a liquid or on a surface  relevant cells, molecules, etc. Specifity is relative, not as specific as an enzymatic reaction, biocompatibility is very good, contact to the body is possible, therefore also applicable in medical devices with direct contact to the blood, not only in in-vitro diagnostic devices. Different to strips with enzymes which only can be used one time, EIS devices can be used continuously and limitations of usage time lines are set only by hygienic aspects like at all medical devices in direct contact with the body.

The different applications (e.g. flow-through for blood lines, a wristband to measure through the skin in the radial artery) require different antenna geometries, with patent pending. In addition the algorithms convert the impedances as complex figures, real and imaginary part, into figures of mM (millimolar, also equ. to millimoles per litre) of lactate. Lactate levels in the artery and in the veins is very alike due to slow metabolism of lactate.

A review article+ of end of 2011 states, that blood lactate monitoring is good for risk assessment in patients admitted acutely to hospital, the trend in serial (all two hours) serial lactate monitoring will predict in-hospital mortality, esp. above 2.5 mM. Peripheral venous blood lactate is highly correlated with arterial blood lactate.

+ Kruse et al Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine 2011, 19:74.