Patent ID: 8275434

Claim:
A method for measuring blood oxygen content under low perfusion, the method comprising: receiving signals from a light-receiving device representing intensities of two different wavelengths of light attenuated by body tissue; converting the signals, using an analog-to-digital converting circuit, into digital data; collecting, in a memory of a patient monitoring device, the data representative of the intensities of light over a period of time that includes more than one cycle, wherein the collected data is cyclical to indicate blood pulsing through the body tissue; integrating, by a microprocessor, the collected data in the memory over the period of time that includes more than one cycle using an area integration method that determines an area between the collected data and a normalized value of the collected data; and determining, by the microprocessor, based at least in part on the integration of the collected data, a first value of blood oxygen saturation.