Blood parameter measurement

A catheter for measuring the oxygen saturation and hematocrit of a sample of blood at a desired location in a body of a patient, the catheter comprising:

• an elongated catheter tube adapted for insertion into a body of a patient, a distal extremity of the tube guidable to a desired location in the body and having a receptacle for receiving a sample of blood at said location;
• generating means for generating bursts of optical energy, each burst characterized by one of a plurality of preselected wavelengths;
• guide means for guiding the energy into any blood in the receptacle;
• receiving means for receiving the energy after it has passed through the blood in the receptacle;
• measuring means for measuring the intensity of each burst of received energy;
• a memory having a molecular extinction coefficient and an optical scattering coefficient stored therein;
• and
• computing means, operative to read the memory to obtain the molecular extinction coefficient and the optical scattering coefficient and to compute the oxygen saturation and hematocrit of the blood at said location according to the measured intensities of the received bursts of energy and said coefficients.

A catheter for measuring the oxygen saturation and hematocrit of a sample of blood at a desired location in a body of a patient, the cathereter comprising:

• an elongated catheter tube adapted for insertion into the body of the patient, a distal extremity of the tube guidable to the desired location in the body and having a receptacle for receiving a sample of blood at said location;
• a light source adapted to provide sequential bursts of optical energy of a plurality of preselected wavelengths;
• a first optical fiber coupled to the light source to couple the bursts of optical energy to the sample of blood in the receptacle;
• a second optical fiber disposed at the opposite side of the receptacle from the first fiber and which directly receives the bursts of optical energy from the first fiber after they have passed through the sample of blood in the receptacle;
• a third optical fiber coupled to the second optical fiber for conducting the energy received by the second optical fiber;
• a characterization device which stores a value representing the distance between the first and second optical fibers and values representing the preselected wavelengths;
• a memory having a plurality of molecular extinction coefficients and optical scattering coefficients stored therein;
• and
• a processor adapted to read the values from the characterization device and read the plurality of molecular extinction coefficients and optical scattering coefficients stored in the memory and adapted to derive a molecular coefficient of extinction and an optical scattering coefficient for each of the preselected wavelengths, and also adapted to receive the optical energy conducted by the third optical fiber and to compute the oxygen saturation and hematocrit of the sample of blood according to the intensities of the received bursts of energy, the characterization values and the derived coefficients.

A method of measuring a parameter of a sample of blood, the method comprising:

• disposing a receptacle at a selected location in the body of a patient;
• collecting the sample of blood in the receptacle;
• passing sequential bursts of optical energy through the sample of blood, each burst characterized by one of a plurality of preselected wavelengths;
• storing a predetermined molecular extinction coefficient and an optical scattering coefficient;
• measuring the intensity of each burst of energy after it has passed through the sample;
• reading the stored coefficients;
• and
• computing a parameter of the sample blood according to the measured intensities of the received bursts of energy and according to said predetermined molecular extinction coefficient and optical scattering coefficient.