Introducer sheath with electrodes

• US 9,078,627 B2
• Filed: 05/10/2012
• Issued: 07/14/2015
• Est. Priority Date: 01/04/2008
• Status: Active Grant

• Current Assignee: Texas Heart Institute
• Original Assignee: Texas Heart Institute
• Inventors: Razavi, Mehdi, Arevalos, Christopher Alexander, Brewer, Maurice Alan
• Primary Examiner(s): Ghafoorian, Reza
• Application Number:
  US13/468,774
• Publication Number:
  US 20120220848A1
• Time in Patent Office: 1,160 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/02042 Determining blood loss or bleeding, e.g. during a surgical procedure
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/07 Endoradiosondes
• CPC Class Codes: A61B 5/6851 Guide wires
• CPC Class Codes: A61B 5/6852 Catheters
• CPC Class Codes: A61B 5/6885 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61M 25/0662 Guide tubes

Abstract

An introducer comprise a sheath for introducing a catheter into a blood vessel, a plurality of electrodes on the sheath, and an impedance assessment unit provided on the sheath and connected to the electrodes. The impedance assessment unit fixes one of a current or voltage across a first pair of the electrodes and measures the other of the current or voltage across a second pair of electrodes.

Claims

1. An introducer, comprising:

a sheath for introducing a catheter into a blood vessel at an insertion site;

a plurality of electrodes on the sheath; and

an impedance assessment unit provided on said sheath and connected to said electrodes, said impedance assessment unit includes a power source, a wireless transceiver and is configured to inject one of a known current or known voltage across a first pair of the electrodes and measures the other of the current or voltage across a second pair of electrodes;

wherein the impedance assessment unit is configured to compute an impedance based on the current and voltage and detect a bleed at the insertion site based on the computed impedance;

wherein the impedance assessment unit is configured to transmit a value indicative of the bleed through the wireless transceiver to an external apparatus.

2. The introducer of claim 1 wherein the impedance assessment unit comprises a controller, a source unit and a measurement unit, wherein the controller is configured to cause the source unit to provide the known current or voltage to the first pair of electrodes and receive from the measurement unit a measured value of the current or voltage.

3. The introducer of claim 2 wherein the controller is configured to initiate impedance measurements at multiple different frequencies.

4. The introducer of claim 2 wherein the controller is configured to receive a command via the wireless transceiver to initiate an impedance measurement.

5. The introducer of claim 1 wherein the known current or voltage is an alternating current (AC) current or voltage.

6. The introducer of claim 5 wherein the impedance assessment unit initiates multiple impedance measurements by serially injecting the known current or voltage at various pre-defined frequencies while simultaneously measuring the other of the current or voltage.

7. The introducer of claim 6 wherein the impedance measurement unit computes impedances based on multiple currents and voltages, and detects the bleeding through comparison of each computed impedance to a baseline impedance.

8. The introducer of claim 1 wherein a magnitude or frequency of the known current or voltage is variable by the impedance assessment unit.

9. The introducer of claim 1 wherein the wireless transceiver is a bi-directional wireless transceiver configured to receive a signal from an external device and transmit a value indicative of the bleeding to the external device.

10. The introducer of claim 9 wherein the received signal includes a command to take an impedance measurement.

11. The introducer of claim 9 wherein the received signal includes a command to program an amplitude or frequency of the known current or voltage.

12. The introducer of claim 9 wherein the value indicative of the bleed includes an alarm signal.

13. The introducer of claim 1 wherein the impedance assessment unit is configured to make a plurality of impedance measurements and average the measurements together.

14. The introducer of claim 1 wherein the impedance assessment unit is configured to compare the computed impedance value to a previously computed impedance value.

15. The introducer of claim 14 wherein the impedance assessment unit is configured to compute the time rate of change of the computed impedance value relative to a previously computed impedance value.

16. The introducer of claim 1 further comprising an indicator activated by the impedance assessment unit upon detection of the bleed.

17. The introducer of claim 16 wherein the indicator is at least one of a visual indicator and an audible indicator.

18. The introducer of claim 1 wherein the impedance assessment unit comprises a current source and a voltage monitor.

19. The introducer of claim 1 wherein the impedance assessment unit comprises a voltage source and a current monitor.

20. The introducer of claim 1 wherein the sheath has a hub and the impedance assessment unit is provided in the hub.