Method of Locating the Tip of a Central Venous Catheter

• US 20130338517A1
• Filed: 08/16/2013
• Published: 12/19/2013
• Est. Priority Date: 10/23/2006
• Status: Active Grant

• Current Assignee: BARD Access Systems Incorporated (Becton, Dickinson & Co)
• Original Assignee: BARD Access Systems Incorporated (Becton, Dickinson & Co)
• Inventors: Rothenberg, Peter M.
• Granted Patent: US 8,858,455 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/06 Devices, other than using radiation, for detecting or locating foreign bodies for removing same A61B17/50 ; determining position of probes within or on the body of the patient
• CPC Class Codes: A61B 5/061 Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body A61B1/00158 takes precedence
• CPC Class Codes: A61B 5/065 Determining position of the probe employing exclusively positioning means located on or in the probe, e.g. using position sensors arranged on the probe
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/353 Detecting P-waves
• CPC Class Codes: A61B 5/6852 Catheters

Abstract

A method of locating a tip of a central venous catheter (“CVC”) having a distal and proximal pair of electrodes disposed within the superior vena cava, right atrium, and/or right ventricle. The method includes obtaining a distal and proximal electrical signal from the distal and proximal pair of electrodes and using those signals to generate a distal and proximal P wave, respectively. A deflection value is determined for each of the P waves. A ratio of the deflection values is then used to determine a location of the tip of the CVC. Optionally, the CVC may include a reference pair of electrodes disposed within the superior vena cava from which a reference deflection value may be obtained. A ratio of one of the other deflection values to the reference deflection value may be used to determine the location of the tip of the CVC.

Claims

1. A computer-readable medium having computer executable instructions for determining the location of a tip of a central venous catheter based on a reference P wave, a first P wave detected by a first pair of electrodes disposed near the tip of the central venous catheter, and a second P wave detected by a second pair of electrodes disposed on the central venous catheter and spaced proximally from the first pair, the instructions comprising:

calculating a first deflection value as a function of the first P wave;

calculating a second deflection value as a function of the second P wave;

calculating a reference deflection value as a function of the reference P wave;

comparing the first deflection value to the second deflection value;

comparing the reference P wave with at least one of the first and second P waves; and

determining a location of the tip of the central venous catheter based on the comparison of the first and second deflection values and the comparison of the reference P wave with at least one of the first and second P waves.

2. The computer-readable medium according to claim 1, wherein the instructions for comparing the first and second deflection values comprise instructions for calculating a first ratio of the first deflection value to the second deflection value, and wherein the instructions for determining the location of the tip of the central venous catheter based on the comparison of the first and second deflection values and the comparison of the reference P wave with at least one of the first and second P waves comprise instructions for comparing the first ratio to a predetermined maximum threshold.

3. The computer-readable medium according to claim 1, wherein the instructions for comparing the first and second deflection values comprise instructions for calculating a first ratio of the first deflection value to the second deflection value, and wherein the instructions for determining the location of the tip of the central venous catheter based on the comparison of the first and second deflection values and the comparison of the reference P wave with at least one of the first and second P waves comprise instructions for comparing the first ratio to a predetermined minimum threshold.

4. The computer-readable medium according to claim 1, wherein the instructions for comparing the reference P wave with at least one of the first and second P waves comprise instructions for calculating a second ratio of one of the first and second deflection values to the reference deflection value, and wherein the instructions for determining the location of the tip of the central venous catheter based on the comparison of the first and second deflection values and the comparison of the reference P wave with at least one of the first and second P waves comprise instructions for comparing the second ratio to a predetermined maximum threshold.

5. The computer-readable medium according to claim 1, wherein the first, second, and reference P waves each comprise a series of discrete numerical values, and wherein the instructions for calculating the first, second and reference deflection values as a function of the first, second, and reference P waves comprise instructions for:

determining the maximum value within the series of discrete numerical values of the P wave;

determining the minimum value within the series of discrete numerical values of the P wave;

determining the polarities of the maximum and minimum values;

comparing the polarity of the maximum value to the polarity of the minimum value;

determining the larger of the absolute value of the maximum value and the absolute value of the minimum value; and

totaling the absolute values of the maximum and minimum values.

6. The computer-readable medium according to claim 1, further comprising computer executable instructions for storing the reference deflection value and for recalling the reference deflection value.

7. The computer-readable medium according to claim 6, further comprising computer executable instructions for associating the stored reference deflection value with a patient.

8. A method of locating a tip of a central venous catheter having a portion disposed within the superior vena cava, the catheter comprising a distal pair of electrodes and a proximal pair of electrodes spaced longitudinally from the distal pair of electrodes, the method comprising:

obtaining a distal electrical signal from the distal pair of electrodes;

generating a first P wave from the distal signal;

determining a first deflection value of the first P wave;

obtaining a proximal electrical signal from the proximal pair of electrodes;

generating a second P wave from the proximal signal;

determining a second deflection value of the second P wave;

calculating a first ratio from the first and second deflection values;

obtaining superior vena cava deflection valued;

calculating a second ratio of one of the first deflection value and the second deflection value to the superior vena cava deflection value;

without advancing or withdrawing the tip of the central venous catheter, determining that the tip of the central venous catheter is located in a desired location when the first ratio and second ratio are both approximately one; and

without advancing or withdrawing the tip of the central venous catheter, determining that the tip of the central venous catheter has been inserted too far when the second ratio is greater than a maximum predefined threshold value, when the first ratio is greater than the maximum predefined threshold value, or when the first ratio is less than a minimum predefined threshold value.

9. The method according to claim 8, wherein the maximum predefined threshold value is two, and the minimum predefined threshold value is one half.