No abstract

An oximeter is described which employs two bundles of flexible glass fibers to conduct appropriately filtered light into, and that light diffusely reflected by the blood out of, the blood stream for the determination of oxygen saturation or dye concentration within blood flowing past the tip of either an arterial needle or a cardiac catheter which contains both bundles. The ratio of intensities of the reflected light at two wavelengths is linearly related to oxygen saturation (IRR805/ IRR660) and dye concentration (IRR900/IRR805). Data is reported in vivo and in vitro with respect to accuracy of the determinations (± 1.9%). The effect of patient-to-patient variation in hematocrit and other factors, and of pulsatile blood flow, is described. Application of the technique to physiologic study is illustrated, and theoretical aspects of reflection oximetry, as they apply to the instrument, are discussed. Submitted on November 17, 1961

An in vivo oximeter which uses as a probe a standard cardiac catheter or a Cournand needle is described. The oxygen saturation is obtained from the light intensities at two wavelengths (805 and 660 m",) diffusely reflected by the unhemolyzed blood. The light is brought to the tip of the catheter and back again to the proximal end by means of glass fibers. Details of the construction of the instrument and experimental results are given. Drabkin and Schmidt. 8 E.

Intracardiac blood oxygen saturation was determined in 31 patients, at cardiac catheterization, by means of a fiberoptic in vivo hemoreflection system, giving an immediate report. When compared to in vitro spectrophotometric analysis of samples obtained through a second catheter, a standard error of estimate of only 1.99-per cent saturation (r = 0.966) was found for the higher speed instrument (response time 0.07 second) and 1.13-per cent saturation (r = 0.992) for the slower instrument (response time 1.5 seconds). The average of the standard deviations of saturation values in cardiac chambers in which no primary mixing occurred, was only 0.88-per cent saturation. The continuous recording of oxygen saturation while moving the catheter, permits measurements at multiple sites within a brief period of time (14 to 26 seconds through the right side of the heart). Oxygen saturation changes can be continuously monitored under changing conditions, such as exercise. Finally, the higher speed instrument permits investigation of changes in oxygen saturation in patients with congenital heart disease within portions of the cardiac cycle.