Determining Absolute and Relative Tissue Oxygen Saturation

A method comprising:

• contacting a probe tip to a target tissue of a patient;
• transmitting first light at a first time from a source structure of the oximeter probe into the target tissue;
• detecting first reflected light that is reflected from the target tissue by a plurality of detector structures of the oximeter probe;
• generating by the detector structures first reflectance data for the first reflected light detected by the detector structures;
• fitting the reflectance data to a plurality of simulated reflectance curves;
• determining one or more best fitting ones of the simulated reflectance curves from the fit of the first reflectance data to the plurality of simulated reflectance curves, wherein each of the simulated reflectance curves is associated with a value for an oximeter parameter;
• determining at least a first oximeter parameter for the one or more best fitting ones of the simulated reflectance curves to the first reflectance data;
• determining a first value for a first oximeter measurement based on the first oximeter parameter;
• storing the first value for the first oximeter measurement in the memory;
• transmitting second light at a second time from the source structure of the oximeter probe into the target tissue;
• detecting second reflected light that is reflected from the target tissue by the plurality of detector structures of the oximeter probe;
• generating by the detector structures second reflectance data for the second reflected light detected by the detector structures;
• fitting the second reflectance data to the plurality of simulated reflectance curves;
• determining one or more best fitting ones of the simulated reflectance curves from the fit of the second reflectance data to the plurality of simulated reflectance curves;
• determining at least a second oximeter parameter for the one or more best fitting ones of the simulated reflectance curves to the second reflectance data;
• determining a second value for a second oximeter measurement based on the second absorption coefficient;
• retrieving the first value from the memory;
• determining a percentage difference between the first and second value;
• and
• displaying the percentage difference on a display of the oximeter probe.