Propofol detection and quantification in human blood: the promise of feedback controlled, closed-loop anesthesia

The performance of a membrane-coated voltammetric sensor for propofol (2,6-diisopropylphenol) has been characterized in long term monitoring experiments using an automated flow analytical system (AFAS) and by analyzing human serum and whole blood samples by standard addition. It is shown that the signal of the membrane-coated electrochemical sensor for propofol is not influenced by the components of the pharmaceutical formulation of propofol (propofol injectable emulsion). The current values recorded with the electrochemical propofol sensor in buffer solutions and human serum samples spiked with propofol injectable emulsion showed excellent correlation with the peak heights recorded with an UV-Vis detector during the HPLC analysis of these samples (R-2 = 0.997 in PBS and R-2 = 0.975 in human serum). However, the determination of propofol using the electrochemical method is simpler, faster and has a better detection limit (0.08 +/- 0.05 mM) than the HPLC method (0.4 +/- 0.2 mM). As a first step towards feedback controlled closed-loop anesthesia, the membrane-coated electrochemical sensor has been implemented onto surface of an intravenous catheter. The response characteristics of the membrane-coated carbon fiber electrode on the catheter surface were very similar to those seen using a macroelectrode.