System and method for in-vivo hematocrit measurement using impedance and pressure plethysmography
First Claim
1. An assemblage for noninvasively measuring a patient'"'"'s hematocrit, comprising:
- a first pair of electrodes configured to at least partially contact a body part of the patient at which hematocrit is to be measured, said first pair of electrodes being connectable to an electrical current source;
a second pair of electrodes configured to at least partially contact the body part at which hematocrit is to be measured, said second pair of electrodes being connectable to an electrical impedance measurement apparatus; and
a pressurization component comprising;
an at least partially hollow, outer rigid member; and
at least one inner pliable member disposed within said outer rigid member, said at least one inner pliable member being partially sealed against said outer rigid member to form a pressurization bladder between said outer rigid member and said at least one inner pliable member, said at least one inner pliable member including a receptacle including a closed end and being configured to receive at least a portion of a body part, said pressurization component being configured to apply pressure externally to said at least a portion of the body part, at least one electrode of said first and second pairs of electrodes being positionable between a portion of said pressurization component and said at least a portion of the body part.
1 Assignment
0 Petitions
Accused Products
Abstract
The hematocrit of blood (i.e., the percentage of whole blood volume occupied by red blood cells) perfusing a finger is determined by stimulating the finger with two current frequencies, one relatively high (e.g., 10 MHZ) and the other relatively low (e.g., 100 KHz). Voltages induced in the finger in response to the two current frequencies are then captured and separated into baseline and pulsatile components. The hematocrit is determined as a function of the ratio of the high frequency pulsatile component to the low frequency pulsatile component, multiplied by the ratio of the square of the low frequency baseline component to the square of the high frequency baseline component. The volume of blood perfusing the body part at which hematocrit is to be measured may be increased on each pulse by the application of external pressure to the finger, such as by applying a pressure cuff to the finger. Assemblages including two pairs of electrodes are used to effect the determination of hematocrit. The assemblages may also include a component for applying pressure to the body part at which hematocrit is measured.
25 Citations
24 Claims
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1. An assemblage for noninvasively measuring a patient'"'"'s hematocrit, comprising:
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a first pair of electrodes configured to at least partially contact a body part of the patient at which hematocrit is to be measured, said first pair of electrodes being connectable to an electrical current source;
a second pair of electrodes configured to at least partially contact the body part at which hematocrit is to be measured, said second pair of electrodes being connectable to an electrical impedance measurement apparatus; and
a pressurization component comprising;
an at least partially hollow, outer rigid member; and
at least one inner pliable member disposed within said outer rigid member, said at least one inner pliable member being partially sealed against said outer rigid member to form a pressurization bladder between said outer rigid member and said at least one inner pliable member, said at least one inner pliable member including a receptacle including a closed end and being configured to receive at least a portion of a body part, said pressurization component being configured to apply pressure externally to said at least a portion of the body part, at least one electrode of said first and second pairs of electrodes being positionable between a portion of said pressurization component and said at least a portion of the body part. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An assemblage for noninvasively measuring a patient'"'"'s hematocrit, comprising:
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a first pair of elongate electrodes configured to at least partially contact a body part of the patient at which hematocrit is to be measured in mutually parallel relation to one another, said first pair of elongate electrodes being connectable to an electrical current source;
a second pair of elongate electrodes configured to at least partially contact the body part at which hematocrit is to be measured in mutually parallel relation to one another, said second pair of elongate electrodes being connectable to an electrical impedance measurement apparatus; and
at least one retention component on at least one elongate electrode of each of said first and second pairs of elongate electrodes with one of said first and second pairs of elongate electrodes being positioned between the other of said first and second pairs of elongate electrodes, said at least one retention component being configured to secure at least one elongate electrode to the body part and including a receptacle on said at least one elongate electrode and an end portion of said at least one elongate electrode being configured to interconnect with said receptacle, said end portion including;
retaining regions, each retaining region having a retaining width that is greater than a receptacle width of said receptacle; and
a constricted region located adjacent each retaining region, said constricted region having a constricted width that is at most about equal to said receptacle width. - View Dependent Claims (23, 24)
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Specification