Biomedical Engineering Reference
In-Depth Information
Fig. 4.49.
Changes in the oxidation current that are detected by the sensing system
which is shown in Fig. 4.48. The oxidation current of the dialytic solution increased
(with fluctuations) with a time delay of approximately 90 s after catecholamines
were added to the original (dialyzed) goat plasma or phosphate-buffered solution
(Fig. 4.49). The ratio and the time delay generally decreased in inverse pro-
portion to the increase in the flow rate of the dialytic solution. Using this
system, it was possible to alter the driving air pressure and pulse rate in accor-
dance with the algorithm for changes in the catecholamine concentration of
the plasma in which the sensor was immersed, although the minimum detec-
table concentration of both plasma adrenaline and noradrenaline decreased
to 10
−
7
mol/l.
Thus, the use of an electrochemical detector in conjunction with the
microdialysis method shows the future possibility of developing a feedback
