Extravasation detection technique
First Claim
1. The method of detecting extravasation that may occur when a needle is inserted into a patient for the purpose of delivering fluid into the patient'"'"'s vascular system comprising the steps of:
- prior to the delivery of fluid, establishing an impedance baseline for patient tissue impedance near the tip of the needle;
determining an impedance slope value based on deviations from said baseline for each of a plurality of time based epochs during the delivery of fluid, and signaling extravasation when said slope values are outside a first predetermined threshold with a consistency that meets a predetermined consistency criterion.
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Abstract
The technique for detecting extravasation during the injection of fluid into a patient involves the establishment of a baseline representing impedance at the zone of the injection prior to the injection starting. Extravasation is signaled when at least two characteristics appear. First is that the impedance varies from the baseline more than a predetermined amount in more than a predetermined number of discreet time slots called epochs herein. Second is that, the rate of change of the impedance, which is called the slope herein, is consistently greater than a predetermined amount.
28 Citations
45 Claims
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1. The method of detecting extravasation that may occur when a needle is inserted into a patient for the purpose of delivering fluid into the patient'"'"'s vascular system comprising the steps of:
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prior to the delivery of fluid, establishing an impedance baseline for patient tissue impedance near the tip of the needle;
determining an impedance slope value based on deviations from said baseline for each of a plurality of time based epochs during the delivery of fluid, and signaling extravasation when said slope values are outside a first predetermined threshold with a consistency that meets a predetermined consistency criterion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. The method of detecting extravasation that may occur when a needle is inserted into a patient for the purpose of introducing fluid into the patient'"'"'s vascular system comprising the steps of:
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prior to the delivery of fluid, establishing an epoch impedance baseline for patient tissue impedance near the tip of the needle based on a first sliding window of epochs, establishing a noise exclusion gate around said epoch impedance baseline, during the delivery of fluid, counting the number of consecutive impedance averages outside of said gate to provide a first count, establishing a second sliding window of epochs, determining an impedance slope for epoch impedance values over each of said second sliding windows of epochs, counting the number of consecutive ones of said impedance slopes having a value outside of a predetermined range to provide a second count, counting the total number of said impedance slopes having a value outside of said predetermined range to provide a third count, signaling extravasation when (a) said first count is greater than a first predetermined number, (b) said second count is greater than a second predetermined number, and (c) said third count is greater than a third predetermined number. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A non-invasive method of detecting extravasation when fluid is delivered into a patient'"'"'s vascular system, comprising:
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a) providing first and second electrodes;
the electrodes being separated from each other to encompass the vicinity around an end of a channel inserted in the patient'"'"'s vascular system for delivering fluid into the vascular system;
b) the first and second electrodes defining a measuring zone;
the measuring zone being sized to detect extravasation in the measuring zone;
c) providing third and fourth electrodes to induce a signal between the first and second electrodes;
said signal being a function of tissue impedance in the measuring zone; and
d) ascertaining if an extravasation has occurred by measuring changes in impedance within the measuring zone. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31)
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32. A non-invasive method of detecting extravasation when fluid is delivered into a patient'"'"'s vascular system, comprising:
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a) providing first and second electrodes and third and fourth electrodes, said first and second electrodes being spaced from one another on either side of a center line, said first and second electrodes defining a measuring zone, said measuring zone being shaped and dimensioned to encompass within said zone an end of a channel inserted in a patient'"'"'s vascular system for delivering fluid into the vascular system, said zone being sized to detect extravasation in the measuring zone and long enough to facilitate placement of the end of the channel within the measurement zone;
each of said third and fourth electrodes being outward, relative to said center line,b) energizing said third and fourth electrodes to provide a field which induces a signal in said first and second electrodes that is a function of tissue impedance in said measuring zone, and c) ascertaining if an extravasation has occurred by measuring changes in impedance within the measuring zone. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40)
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41. A non-invasive method of detecting extravasation when fluid is delivered into a patient'"'"'s vascular system, comprising:
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a) providing first and second electrodes;
the electrodes being separated from each other to encompass the vicinity around an end of a channel inserted in the patient'"'"'s vascular system for delivering fluid into the vascular system;
b) the first and second electrodes defining a measuring zone;
the measuring zone being sized to detect extravasation in the measuring zone;
c) providing third and fourth electrodes to induce a signal between the first and second electrodes;
said signal being a function of tissue impedance in the measuring zone;
d) ascertaining if an extravasation has occurred by measuring changes in impedance within the measuring zone; and
e) wherein the first, second, third and fourth electrodes are substantially the same length.
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42. A non-invasive method of detecting extravasation when fluid is delivered into a patient'"'"'s vascular system, comprising:
providing first and second electrodes;
the electrodes being separated from each other to encompass the vicinity around an end of a channel inserted in the patient'"'"'s vascular system for delivering fluid into the vascular system;
a) the first and second electrodes defining a measuring zone;
the measuring zone being sized to detect extravasation in the measuring zone;
b) providing third and fourth electrodes to induce a signal between the first and second electrodes;
said signal being a function of tissue impedance in the measuring zone;
c) ascertaining if an extravasation has occurred by measuring changes in impedance within the measuring zone; and
d) wherein the first, second, third and fourth electrodes are about 3 inches in length and about 3/16th of an inch wide.
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43. A non-invasive method of detecting extravasation when fluid is delivered into a patient'"'"'s vascular system, comprising:
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a) providing first and second electrodes;
the electrodes being separated from each other to encompass the vicinity around an end of a channel inserted in the patient'"'"'s vascular system for delivering fluid into the vascular system;
b) the first and second electrodes defining a measuring zone;
the measuring zone being sized to detect extravasation in the measuring zone;
c) providing third and fourth electrodes to induce a signal between the first and second electrodes;
said signal being a function of tissue impedance in the measuring zone;
d) ascertaining if an extravasation has occurred by measuring changes in impedance within the measuring zone; and
e) wherein the first, second, third and fourth electrodes are silver/silver chloride strips.
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44. A non-invasive method of detecting extravasation when fluid is delivered into a patient'"'"'s vascular system, comprising:
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a) providing first and second electrodes;
the electrodes being separated from each other to encompass the vicinity around an end of a channel inserted in the patient'"'"'s vascular system for delivering fluid into the vascular system;
b) the first and second electrodes defining a measuring zone;
the measuring zone being sized to detect extravasation in the measuring zone;
c) providing third and fourth electrodes to induce a signal between the first and second electrodes;
said signal being a function of tissue impedance in the measuring zone;
d) ascertaining if an extravasation has occurred by measuring changes in impedance within the measuring zone; and
e) wherein the first and second electrodes are parallel relative to each other.
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45. A non-invasive method of detecting extravasation when fluid is delivered into a patient'"'"'s vascular system, comprising:
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a) providing first and second electrodes;
the electrodes being separated from each other to encompass the vicinity around an end of a channel inserted in the patient'"'"'s vascular system for delivering fluid into the vascular system;
b) the first and second electrodes defining a measuring zone;
the measuring zone being sized to detect extravasation in the measuring zone;
c) providing third and fourth electrodes to induce a signal between the first and second electrodes;
said signal being a function of tissue impedance in the measuring zone;
d) ascertaining if an extravasation has occurred by measuring changes in impedance within the measuring zone; and
e) wherein the fourth and fifth electrodes are parallel to each other.
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Specification