Patent ID: 8666468

Claim:
A method of determining blood vessel flow state comprising: generating a plurality of stored data points wherein a data point comprises an oxygen saturation value and a perfusion index value, the plurality of data points generated periodically by: determining an oxygen saturation value of blood from measured red and infrared light absorption characteristics of tissue at a tissue monitoring site monitored by a physiological sensor; determining a perfusion index value from the measured infrared light absorption characteristic of the tissue at the measuring site; and storing the measured oxygen saturation and perfusion index; determining a relationship between the stored data points; comparing the determined relationship with stored microcirculation data corresponding to a blocked or partially blocked microcirculation state, the stored microcirculation data representing a relationship between oxygen saturation and perfusion index; and determining a current microcirculation state of at least a portion of blood vessels at the monitoring site from the comparison with the microcirculation data.