System and method for monitoring bioimpedance and respiration
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.
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.