Sampling and Monitoring of Metabolites in Human Whole Blood

Objective: To evaluate methods for bed-side blood monitoring systems. The study was performed to evaluate a method for real-time glucose and lactate monitoring, to improve this monitoring system and to evaluate off-line systems for discrete analysis of metabolites in human whole blood. Methods: First, a double lumen catheter system for the prevention of blood coagulation connected to a sensor flow cell was used, second a heparin coated catheter and tubing system connected to a sensor flow cell was used for obtaining continuous measurements of glucose and lactate. Two different sensor types (thin-film and thick-film technology) were used in the experimental setups. Sensor performance as well as sampling system performance was tested by means of in vitro investigations and by clinical experiments. Additionally, the performance of discrete blood glucose measurement systems was examined. Results: Human whole blood could be monitored continuously. Improved results could be observed when using a heparin coated tubing and sampling system. Human whole blood could be monitored at flow rates between 16 µl/min and 5 ml/min. In comparison to these real-time monitoring methods several devices for off-line discrete glucose estimations were tested. Conclusion: Sampling and real-time monitoring of metabolites in undiluted human whole blood is feasible with such a device.