Process for the determination of the hematocrit level of whole blood and apparatus for carrying out the process
First Claim
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1. A process for the determination of the hematocrit level of whole blood including the steps of:
- measuring the conductivity of the whole bloodmeasuring the concentration of sodium ions or chloride ions in the whole blooddetermining the conductivity of blood plasma from the concentration of sodium ions or chloride ions in the whole blood, anddetermining the hematocrit level from the conductivity of the whole blood and the conductivity of blood plasma.
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Abstract
There is described a method and apparatus for the determination of hematocrit levels in which both the conductivity of whole blood and the conductivity of blood plasma are determined together. While a conductivity cell (18) is being used for the determination of the conductivity of whole blood, the conductivity of plasma is calculated in a computer (30) with the aid of ion selective electrodes (14, 16) from the sodium or potassium concentrations.
44 Citations
14 Claims
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1. A process for the determination of the hematocrit level of whole blood including the steps of:
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measuring the conductivity of the whole blood measuring the concentration of sodium ions or chloride ions in the whole blood determining the conductivity of blood plasma from the concentration of sodium ions or chloride ions in the whole blood, and determining the hematocrit level from the conductivity of the whole blood and the conductivity of blood plasma. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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4. A process according to claim 3 in which the constant K amounts to about 72 to 88, the constant A amounts to about 0.058 to 0.082, the constant B amounts to about 1.2×
- A and the constant D amounts to 0 to 2.
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5. A process according to claim 4 in which the constant K is about 80, the constant A is about 0.07 and the constant D is about 1.
- 6. A process according to claim 2 in which use is made of a quadratic approximation corresponding to the equation
- space="preserve" listing-type="equation">Hkt=(P×
N.sup.2)+(Q×
N)
in which Hkt represents the hematocrit level, P lies between 37 and 57, Q lies between 44 and 60, N=1-(LFVB /LFP), LFVB represents the conductivity of whole blood, LFP represents the conductivity of blood plasma and equals (A×
CNa)+(B×
CK)+D where CNa represents the concentration of sodium ions in the whole blood, CK represents the concentration of potassium ions in the whole blood, and A, B and D are correlation constants which are determined from a known value of plasma conductivity. - space="preserve" listing-type="equation">Hkt=(P×
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7. A process according to claim 6 to which P amounts to about 47 and Q amounts to about 52.
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8. A process according to claim 1 in which the determination of ion concentrations is carried out with ion selective electrodes.
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9. Apparatus for the determination of the hematocrit level of whole blood comprising:
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a device for measuring the conductivity of the whole blood, a device for determining the conductivity of blood plasma incorporating a sodium ion selective electrode for measuring the concentration of sodium ions in the whole blood or a chloride ion selective electrode for measuring the concentration of chloride ions in the whole blood and computing means (32 to
40) for the determination of the conductivity of blood plasma in response to a signal from the sodium ion selective electrode or the chloride ion selective electrode, anda determining unit (44) for receiving values from the device for measuring the conductivity of the whole blood and from the computing means (32 to
40) and for determining the hematocrit level from the conductivity of the whole blood and the conductivity of blood plasma. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification