New developments of an optochemical measurement system for the continuous monitoring in subcutaneous tissue by microdialysis

The monitoring of dissolved 02 in blood and organic tissues is extremely useful for physiological and respiratory studies and for monitoring the health conditions of hospitalized patients. Based on these demands an optochemical measurement system for the continuous monitoring of 02 in subcutaneous adipose tissue of critically ill patients is reported The system consists of a miniaturized flow trough cell including an 02 sensitive layer, an optoelectronic measuring unit and a microdialysis catheter for the extraction of the biological fluid. The measurement principle is the phase modulation fluorometry. The sensor allows the 02 measurement in the range 0-300 mmHg, with a resolution better than 1 mmHg and an accuracy better than plusmn1 mmHg. With respect to a previously reported instrumentation, this measurement system shows a high degree of miniaturization and an improved production reproducibility of the optochemical sensing layers. This new instrumentation has been extensively validated in laboratory and in-vivo tests.