Method and apparatus for ratiometric measurement of hematocrit
First Claim
Patent Images
1. A circuit for measuring the conductivity of a blood sample, the circuit including:
- a. a first and second connection point, each connection point being configured to be coupled to a blood conductivity sensor and the second connection point also being configured to be coupled to a drive signal source;
b. a half-wave rectifier coupled to the first connection point; and
c. an integrator coupled to the output of the half-wave rectifier.
2 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for measuring resistance of a blood sample in order to determine the hematocrit of that blood sample. The present invention makes a direct ratiometric measurement. That is, the alternating current that flows through the sample is directly measured by applying that alternating current to an integrator which converts the current to a D.C. voltage which is directly proportional to the applied current.
-
Citations
18 Claims
-
1. A circuit for measuring the conductivity of a blood sample, the circuit including:
-
a. a first and second connection point, each connection point being configured to be coupled to a blood conductivity sensor and the second connection point also being configured to be coupled to a drive signal source; b. a half-wave rectifier coupled to the first connection point; and c. an integrator coupled to the output of the half-wave rectifier.
-
-
2. A circuit for measuring the conductivity of a blood sample in order to determine the hematocrit of the blood sample, the circuit including:
-
a. a first, second, and third connection point, the first and second connection point being configured to be coupled to a first and second electrode of a blood conductivity sensor, the third connection point being configured to be coupled to a drive signal source; b. a half-wave rectifier coupled to the first connection point; c. an integrator coupled to the output of the half-wave rectifier; and d. a filter coupled between the second and third connection point. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A method for measuring hematocrit of a blood sample, including the steps of:
-
a. generating an output drive signal; b. coupling the output drive signal to a first electrode of a blood conductivity sensor; c. coupling a second electrode of the blood conductivity sensor to a half-wave rectifier; d. coupling the output from the half-wave rectifier to an integrator; e. reading the output from the integrator while the blood conductivity electrodes are emersed in a calibrant; f. reading the output from the integrator while the blood conductivity electrodes are emersed in a blood sample; and g. determining the hematocrit value of the blood sample by generating a ratio φ
of the integrator output read when the blood conductivity sensor electrodes were emersed in the blood sample with respect to the integrator output read when the blood conductivity sensor electrodes were emersed in the calibrant and applying the ratio φ
to the formula;
space="preserve" listing-type="equation">H=a 1n φ
-b;where H is the hematocrit value of the blood sample, a is a first known cell constant, and b is a second known cell constant. - View Dependent Claims (17, 18)
-
Specification