In accordance with one embodiment of the invention, a system is provided for the monitoring of blood analytes using optical probes in the circulatory system. The probes can be inserted on the venous side of the circulatory system. In another embodiment, methods and apparatuses can be used for processing continuous information generated from indwelling intravascular or tissue optical sensors including, but not limited to, measuring gas concentrations, pH, temperature, and other analytes of blood or tissue. In another embodiment, analyte values can be displayed and analyzed to determine if the values fall outside of normal physiological parameters. Trends of one or multiple analyte values can be analyzed and extrapolated to predict any impending, deleterious condition. In one embodiment, an alarm can be transmitted to appropriate personnel when criterion/criteria are met. In yet another embodiment, devices can be inhibited from delivering continuous infusions of medicine to patients.