Method and apparatus for monitoring metabolism in body organs

Abstract

A spectrophotometric transillumination method and apparatus are directed to non-invasive, continuous, atraumatic, in vivo, in situ monitoring of metabolism in a body organ. In the described applications, measuring and reference wavelengths within the near infrared region, i.e., 700-1300 nm, are utilized for non-invasive, continuous, atraumatic, in situ, in vivo monitoring of oxidative metabolism by monitoring oxygen sufficiency in an internal organ, e.g., the brain or heart, of a human or animal body. Advantage is taken of the critical characteristic of cellular enzyme cytochrome a, a.sub.3 within the optical path and within the radiated portion of the selected organ for absorbing the selected measuring wavelength and for light of this measuring wavelength, as well as at least one reference wavelength within the same defined infrared region and at a low, non-hazardous level of intensity to travel through and be detectable at the end of a relatively long path, e.g., of several centimeters length, which may include substantial content of bone as well as soft tissue. The selection of wavelengths, circuitry and method also provide techniques for compensating for changes in blood volume in the organ being monitored, for continuous monitoring of hemoglobin oxygenation and blood volume and for intermittent monitoring of blood flow rate.