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, andsignaling extravasation when said slope values are outside a first predetermined threshold with a consistency that meets a predetermined consistency criterion.
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Accused Products
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.
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Citations
22 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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Specification