Patent ID: 7239902

Claim:
A device for measuring a body-tissue water content metric as a fraction of the fat-free tissue content of a patient using optical spectrophotometry, comprising: a probe housing configured to be placed proximal to a tissue location which is being monitored; light emission optics connected to the housing and configured to direct radiation at the tissue location; light detection optics connected to the housing and configured to receive radiation from the tissue location; and a processing device configured to process radiation from the light emission optics and the light detection optics and to compute the metric wherein the metric comprises a ratio of the water content of a portion of patient's tissue in relation to the lean or fat-free content of a portion of patient's tissue, wherein the processing device receives and compares at least two sets of optical measurements from at least two different wavelengths, where absorption of light at the at least two different wavelengths is primarily due to water which is in the vascular blood and in the extravascular tissue, and where a ratio of the at least two measurements provides a measure proportional to the difference between the fractions of water in the blood and surrounding tissue location.