System and method for detecting venous needle dislodgement
Inventors
Schaefer, Robert • Schaefer, Gareth T. • MacIntosh, Scott • Sinha, Dipen N. • Espina, Peter G. • Crnkovich, Martin J.
Assignees
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Publication Number
US-12296083-B2
Publication Date
2025-05-13
Expiration Date
Abstract
In one aspect, a method and system for detecting a change in fluid dynamics of a fluid flowing through an extra-corporeal circuit is disclosed, which includes establishing an acoustic wave resonance across a transverse dimension of at least a portion of a line associated with the extra-corporeal circuit through which the fluid flows, monitoring a phase signal of the resonant acoustic wave, and identifying occurrence of a change in fluid dynamics of the flowing fluid when the observed phase signal of the resonant acoustic wave indicates a deviation from the expected fluid flow signature. The change in fluid dynamics can be used to indicate a venous needle dislodgement event.
Core Innovation
The invention provides a dialysis venous needle dislodgement detection system and method that establishes a resonant standing acoustic wave substantially perpendicular to fluid flow in an extra-corporeal venous return line. The system transmits an acoustic wave into a portion of the line substantially perpendicular to the fluid flow and detects at least a portion of the acoustic wave after its passage through the flowing fluid. The fluid-dynamics change is identified when a monitored phase signal indicates a deviation from an expected phase signature.
The monitored phase signal corresponds to a difference between a phase of the transmitted acoustic wave and a phase of the detected acoustic wave, using a phase detector. The expected phase signature is associated with the fluid flow dynamics and may include a phase signature associated with patient heartbeats coupled to an extracorporeal circuit. In some characterizations, the deviation includes a substantial disappearance of the phase-signal signature to indicate substantially complete dislodgement, including venous return line dislodgement.
A corresponding system is implemented with an acoustic wave transmitter, a detector, a phase detector, and a comparator that compares the measured phase signal to the expected phase signature. The acoustic standing wave is resonant and perpendicular to the fluid flow across a lumen of the line, and the implementation includes acoustic operation using a single frequency in a range of about 1 MHz to about 20 MHz with optional frequency modulation to change the frequency of the resonant standing acoustic wave and monitor phase-signal shifts versus frequency.
Claims Coverage
The document includes three independent claims: one method claim and two system/dialysis-system claims. Across them, the inventive features center on establishing a resonant standing acoustic wave substantially perpendicular to flow, measuring a phase difference between transmitted and detected acoustic waves, and identifying a deviation from an expected phase signature caused by partial dislodgement.
Perpendicular resonant standing acoustic wave established across a fluid-flow line
Establishing a resonant standing acoustic wave substantially perpendicular to said fluid flow across at least a portion of a line associated with said extra-corporeal circuit, wherein the step of establishing comprises transmitting an acoustic wave into said portion of the line substantially perpendicular to said fluid flow and detecting at least a portion of the acoustic wave after its passage through said flowing fluid.
Phase difference monitoring against an expected phase signature
Monitoring a phase signal corresponding to a difference between a phase of said transmitted acoustic wave and a phase of said detected acoustic wave and identifying occurrence of a change in fluid dynamics when the monitored phase signal indicates a deviation from an expected phase signature associated with the fluid flow.
Dislodgement-caused deviation in phase signature
Identifying that the change in fluid dynamics is caused by at least partial dislodgement of another portion of said line, wherein a deviation identified by a comparator between the measured phase signal and the expected phase signature indicates occurrence of an at least partial dislodgement of at least a portion of said line.
Dialysis system with venous blood line acoustic standing-wave phase sensing
Providing a dialysis system with an acoustic sensor coupled to a venous blood line, wherein the acoustic sensor establishes an acoustic standing wave in a portion of the venous blood line substantially perpendicular to blood flow, detects at least a portion of the acoustic standing wave after passage through the flow of blood, and monitors a phase signal corresponding to a difference between phases of transmitted and detected acoustic waves, where a deviation relative to an expected phase signature indicates at least a partial dislodgement of the venous blood line.
Single-frequency acoustic standing wave range
Using an acoustic wave transmitter to generate a single-frequency acoustic wave in the range of about 1 MHz to about 20 MHz to establish the resonant acoustic standing wave.
Substantial disappearance indicating substantially complete dislodgement
Characterizing a deviation in the monitored phase signal by a substantial disappearance of the phase-signal signature to indicate substantially complete dislodgement of a venous return line.
Frequency modulation to determine an optimal resonant frequency
Changing the frequency of a resonant standing acoustic wave using frequency modulation and monitoring phase-signal shifts versus frequency to determine an optimal resonant frequency.
Analyzer/comparator correlation to attribute deviation to dislodgement
Correlating a measured phase deviation in fluid dynamics to identify the event as an at least partial dislodgement of at least a portion of a line from its expected position, by comparing the measured phase signal with the expected phase signature and using a deviation to indicate the dislodgement occurrence.
Releasably coupled acoustic components using a spring-load clamp
Configuring the acoustic wave transmitter and the detector so that they are removably coupled to a line using a spring-load clamp.
Across the independent claims, the invention requires a perpendicular resonant acoustic standing wave in an extra-corporeal or venous line, measurement of a transmitted-versus-detected phase difference, and identification of dislodgement when the phase signal deviates from an expected phase signature. The provided material further includes single-frequency operation, substantial phase-signal disappearance, frequency modulation for resonant optimization, analyzer/comparator correlation, and removable spring-clamp coupling.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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