System and method for detecting venous needle dislodgement

Patent metadata

Field	Value
Publication number	US-12296083-B2
Application number	US-202117364156-A
Country	US
Kind code	B2
Filing date	Jun 30, 2021
Priority date	Jul 2, 2020
Publication date	May 13, 2025
Grant date	May 13, 2025

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.

First claim

What is claimed is:

1. A method of detecting a change in fluid dynamics of a fluid flowing through an extra-corporeal circuit, comprising:
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 through which said fluid flows, wherein the step of establishing the resonant standing acoustic wave 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;
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 the fluid dynamics of said flowing fluid when the monitored phase signal of said resonant acoustic wave indicates a deviation from an expected phase signature associated with the fluid flow; wherein said change in the fluid dynamics is caused by at least partial dislodgement of another portion of said line.

2. The method of claim 1 , wherein said extra-corporeal circuit comprises an extra-corporeal dialysis circuit and said line is a venous return line.

3. The method of claim 1 , wherein said expected phase signature comprises a phase signature associated with heartbeats of a patient coupled to said extra-corporeal circuit.

4. The method of claim 2 , wherein said deviation of said monitored phase signal comprises a substantial disappearance of said signature of the phase signal, indicating a substantially complete dislodgement of said venous return line.

5. The method of claim 1 , wherein said acoustic wave has a single frequency in a range of about 1 MHz to about 20 MHz.

6. The method of claim 1 , further comprising changing frequency of said resonant standing acoustic wave and monitoring a shift in said phase signal as a function of frequency to identify an optimal frequency for said resonant standing acoustic wave,
wherein said step of changing the frequency of the resonant standing acoustic wave comprises applying a frequency modulation to said resonant standing acoustic wave.

7. The method of claim 1 , wherein said deviation from the expected phase signature is caused by an inconsistent flow rate of the fluid.

8. The method of claim 1 , wherein said fluid is blood and further comprising adjusting a flow rate of the blood in response to detection of said change in the fluid dynamics of the flowing fluid.

9. A system for detecting a change in fluid dynamics of a fluid flowing in a line associated with an extra-corporeal circuit, comprising:
an acoustic wave transmitter for establishing a resonant acoustic standing wave substantially perpendicular to said fluid flow across a lumen of said line such that the resonant acoustic standing wave travels through a portion of the fluid traversing through said lumen;
a detector for detecting at least a portion of said resonant acoustic standing wave after its passage through said fluid;
a phase detector for measuring a phase signal indicative of a phase difference between the transmitted acoustic wave and the detected acoustic wave; and
a comparator for comparing the measured phase signal with an expected phase signature associated with the fluid dynamics of said fluid flowing through said line,
wherein a deviation identified by said 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.

10. The system of claim 9 , further comprising an analyzer for correlating said deviation to an event causing the change in the fluid dynamics,
wherein said analyzer is configured to analyze said phase deviation so as to identify said event as an at least partial dislodgement of at least a portion of said line from an expected position.

11. The system of claim 9 , wherein said acoustic wave transmitter is configured to generate an acoustic wave with a single frequency in a range of about 1 MHz to about 20 MHz.

12. The system of claim 10 , wherein said analyzer is configured to identify a deviation of said phase signal corresponding to at least partial dislodgement of said venous return line.

13. The system of claim 10 , wherein said analyzer is configured to correlate a substantial disappearance of said phase signal with a substantially complete dislodgement of said venous return line.

14. The system of claim 9 , wherein any of said acoustic wave transmitter and said detector is releasably coupled to said line with a spring-load clamp.

15. A dialysis system, comprising:
a dialyzer;
an arterial line for providing a path for blood flow from a patient's circulatory system to an inlet port of the dialyzer;
a venous blood line for providing a path for flow of blood exiting the dialyzer to the patient's circulatory system; and
an acoustic sensor coupled to said venous blood line,
wherein said acoustic sensor is configured to:
establish an acoustic standing wave in a portion of the venous blood line substantially perpendicular to blood flow,
detect at least a portion of the acoustic standing wave after passage of the acoustic wave through the flow of blood, and
monitor a phase signal associated with said acoustic wave, said phase signal corresponding to a difference between a phase of said transmitted acoustic wave and a phase of said detected acoustic wave, and

wherein a deviation of said monitored phase signal relative to an expected phase signature indicates at least a partial dislodgement of the venous blood line.

Assignees

• Awe Tech Llc
• Fresenius Medical Care Holdings Inc

Inventors

• Schaefer Robert
• Schaefer Gareth T
• Macintosh Scott
• Sinha Dipen N
• Espina Peter G
• Crnkovich Martin J

Classifications

• A61M2205/3375

  Acoustical, e.g. ultrasonic, measuring means · CPC title

• A61M2205/3344

  Measuring or controlling pressure at the body treatment site · CPC title

• A61M2205/3334

  Measuring or controlling the flow rate · CPC title

• A61M2205/13

  with means for the detection of operative contact with patient, e.g. lip sensor · CPC title

• A61M1/3626

  Gas bubble detectors · CPC title