System and method for monitoring bioimpedance and respiration

• US 9,439,706 B2
• Filed: 02/27/2014
• Issued: 09/13/2016
• Est. Priority Date: 11/18/2005
• Status: Expired due to Fees

• Current Assignee: Medtronic CryoCath LP (Medtronic Plc)
• Original Assignee: Medtronic CryoCath LP (Medtronic Plc)
• Inventors: Asmar, Johnny Al, Abboud, Marwan, Harmouche, Chadi
• Primary Examiner(s): FOWLER, DANIEL WAYNE
• Application Number:
  US14/191,697
• Publication Number:
  US 20140180278A1
• Time in Patent Office: 929 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 18/00 Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body eye surgery A61F9/007; ear surgery A61F11/00
• CPC Class Codes: A61B 18/02 by cooling, e.g. cryogenic techniques devices for cooling specific reflex points of the body within cell-life limits A61H39/06
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 2017/00026 Conductivity or impedance, e.g. of tissue
• CPC Class Codes: A61B 2017/22051 with an inflatable part, e.g. balloon, for positioning, blocking, or immobilisation A61B2017/22048, A61B2017/3486 take precedence
• CPC Class Codes: A61B 2018/0022 Balloons
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/0212 using an instrument inserted into a body lumen, e.g. catheter
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/0809 by impedance pneumography

Abstract

A method of treating tissue is provided, including positioning a portion of a catheter in proximity to cardiac tissue; measuring an impedance value with the catheter; determining a respiratory rate based at least in part on the measured impedance value; and thermally treating the cardiac tissue with the catheter.

Claims

1. A medical system for thermally treating cardiac tissue, the system comprising:

a catheter, the catheter including;

a proximal end, a distal end, and a thermally conductive region;

a first electrode on the catheter proximal to the thermally conductive region;

a second electrode on the catheter proximal to the first electrode; and

an impedance measurement system in communication with the catheter, the impedance measurement system being programmed to;

initiate thermal treatment of tissue proximate a phrenic nerve;

measure an impedance value;

correlate the impedance value to a respiratory status, the respiratory status being a response of the phrenic nerve to the thermal treatment;

define a respiratory status threshold value; and

terminate the thermal treatment of the tissue when the correlated respiratory status is below the predefined threshold value.

2. The medical system of claim 1, wherein the impedance value is measured between the first and second electrodes.

3. The medical system of claim 1, wherein the impedance measurement system includes a signal processing unit.

4. The medical system of claim 1, wherein the second electrode is between approximately 100 mm and approximately 800 mm from the distal tip.

5. The medical system of claim 4, wherein the second electrode is between approximately 10 mm and approximately 800 mm from the first electrode.

6. The medical system of claim 5, wherein the catheter further includes a third electrode and fourth electrode.

7. The medical system of claim 6, wherein the third electrode is proximate the first electrode and the fourth electrode is proximate the second electrode.

8. The medical system of claim 7, wherein the first and second electrodes are configured to provide an excitation current, and the third and fourth electrodes are configured to measure an impedance voltage.

9. A medical system for thermally treating cardiac tissue, the system comprising:

a catheter, the catheter including;

a proximal end, a distal end defining a distal tip, and a thermally conductive region;

a first electrode on the catheter proximal to the thermally conductive region;

a second electrode on the catheter proximal to the first electrode, the first and second electrodes being operable to provide an excitation current;

a third electrode proximate the first electrode; and

a fourth electrode proximate the second electrode, the third and fourth electrodes being operable to measure an impedance value across at least a portion of a thoracic cavity; and

an impedance measurement system in communication with the catheter, the impedance measurement system being programmed to;

initiate thermal treatment of tissue by the thermally conductive region proximate a phrenic nerve;

receive impedance value signals from the third and fourth electrodes;

correlate the impedance value to a respiratory status, the respiratory status being a response of the phrenic nerve to the thermal treatment;

define a respiratory status threshold value; and

terminate the thermal treatment of the tissue when the correlated respiratory status is below the predefined threshold value.

10. The medical system of claim 9, wherein the second electrode is between approximately 100 mm and approximately 800 mm from the first electrode and between approximately 100 mm and approximately 800 mm from the distal tip.