Hematocrit measuring apparatus

Apparatus for measuring the hematocrit of a flowing bloodstream in real time, comprising:

• (a) first means for producing a first hematocrit signal which is a function of the diffusion of an infrared light beam by said bloodstream;
• (b) second means for producing a signal representative of the oxygen saturation of said bloodstream;
• (c) third means for multiplying said first hematocrit signal by a function of said oxygen saturation signal to produce an adjusted hematocrit signal;
• and
• (d) look-up table means for producing a linear hematocrit signal from predetermine combinations of said first hematocrit and oxygen saturation signal.

Apparatus for measuring the hematocrit of a flowing bloodstream in real time, comprising:

• (a) a cuvette adapted to have a bloodstream flowing therethrough, said cuvette having a longitudinal axis;
• (b) a holder for receiving said cuvette;
• (c) first light source and photodetector means mounted, respectively, in said holder so as to detect only diffused light;
• (d) second light source and photodetector means mounted in said holder so as to detect multiple-scattered light;
• (e) third light source and photodetector means mounted in said holder in a position to only see each other;
• and
• (f) resilient, transparent, thermally conductive encapsulation means for providing a seat for positioning said cuvette in said holder, said encapsulation means enclosing all of said light source and photodetector means and maintaining them at substantially the same temperature.

Apparatus for measuring the hematocrit of a flowing bloodstram in real time, comprising:

• (a) transparent cuvette means for containing said flowing bloodstream;
• (b) infrared light source means adjacent said cuvette means for illuminating said bloodstream;
• (c) detector means adjacent said cuvette means for detecting said infrared light after diffusion thereof by said bloodstream;
• (d) signal-producing means for producing a hematocrit signal which is a predetermined function of said detected diffused light;
• and
• (e) said infrared light source means being arranged to emit a beam of light, said detector means having a restricted field of vision, and the intersection of said beam and field being sufficiently deep within said bloodstream to cause said detector means to see substantially only light diffused by said bloodstream.

A method for measuring the hematocrit of a flowing bloodstream in real time, comprising the steps of:

• (a) illuminating said bloodstream with light;
• (b) detecting a first portion of said light diffused by said bloodstream;
• (c) detecting a second portion of said light multiple-scattered by said bloodstream;
• (d) producing an oxygen saturation signal which is a function of said detected multiple-scattered light portion;
• (e) producing a first hematocrit signal which is a function of said detected diffused light portion;
• and
• (f) using said oxygen saturation signal to adjust said first hematocrit signal so as to produce a second hematocrit signal which is independent of oxygen saturation.