METHOD OF LOCATING THE TIP OF A CENTRAL VENOUS CATHETER

• US 20080097232A1
• Filed: 10/23/2006
• Published: 04/24/2008
• 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 7,794,407 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

The invention includes 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 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 method of locating a tip of a central venous catheter, the central venous catheter having a portion disposed within the superior vena cava, 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; and

determining a location of the tip of the central venous catheter based on the first ratio.

2. The method of claim 1, wherein determining the location of the tip of the central venous catheter based on the first ratio comprises:

comparing the first ratio to a maximum threshold value; and

concluding the tip of the central venous catheter is located in the right atrium if the first ratio is equal to or exceeds the maximum threshold value.

3. The method of claim 1, wherein determining a location of the tip of the central venous catheter based on the first ratio comprises:

comparing the first ratio to a minimum threshold value; and

concluding the tip of the central venous catheter is located in the right ventricle if the first ratio is equal to or less than the minimum threshold value.

4. The method of claim 1, wherein determining a location of the tip of the central venous catheter based on the first ratio comprises:

comparing the first ratio to a maximum threshold value and a minimum threshold value; and

concluding the tip may be located in either the superior vena cava or the right atrium if the first ratio is less than the maximum threshold value and greater than the minimum threshold value.

5. The method of claim 1, wherein the portion of the central venous catheter disposed within the superior vena cava has a reference pair of electrodes spaced longitudinally proximally from the proximal pair of electrodes, the method comprising:

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

generating a SVC P wave from the reference signal;

determining a SVC deflection value of the SVC P wave;

calculating a second ratio of one of the first and second deflection values to the SVC deflection value; and

determining a second location of the tip of the central venous catheter based on the second ratio.

6. The method of claim 5, wherein determining the second location of the tip of the central venous catheter based on the second ratio comprises:

comparing the second ratio to a maximum threshold value; and

concluding the tip of the central venous catheter is located in the right atrium if the second ratio is equal to or exceeds the maximum threshold value.

7. The method of claim 1, comprising:

obtaining a SVC deflection value;

calculating a second ratio of one of the first and second deflection values to SVC deflection values; and

determining a second location of the tip of the central venous catheter based on the second ratio.

8. The method of claim 7, wherein determining the second location of the tip of the central venous catheter based on the second ratio comprises:

comparing the second ratio to a maximum threshold value; and

concluding the tip of the central venous catheter is located in the right atrium if the second ratio is equal to or exceeds the maximum threshold value.

9. The method of claim 7, wherein determining the SVC deflection value comprises:

positioning the distal pair of electrodes inside the superior vena cava;

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

generating a SVC P wave from the SVC signal; and

calculating the SVC deflection value from the SVC P wave.

10. The method of claim 7, wherein determining the SVC deflection value comprises:

positioning the proximal pair of electrodes inside the superior vena cava;

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

generating a SVC P wave from the SVC signal; and

calculating the SVC deflection value from the SVC P wave.

11. The method of claim 1, wherein the first P wave comprises a maximum value and a minimum value;

calculating the first deflection value as a function of the first P wave comprises determining the larger of the absolute value of the maximum value and the absolute value of the minimum value when the maximum and minimum values have the same polarity; and

calculating the first deflection value as a function of the first P wave comprises totaling the absolute values of the maximum and minimum values when the maximum and minimum values have opposite polarities.

12. A method of locating a tip of a central venous catheter, the central venous catheter having a portion disposed within the superior vena cava;

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;

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

generating a second P wave from the proximal signal;

comparing 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 P waves.

13. The method of claim 12, wherein the first P wave has a first shape and the second P wave has a second shape and comparing the first and second P waves comprises comparing the first and second shapes.

14. The method of claim 13, wherein the first shape has a first height and the second shape has a second height and determining the location of the tip of the central venous catheter based on the comparison of the first and second shapes comprises concluding the tip of the central venous catheter is located in the right atrium if the first height is at least twice the second height.

15. The method of claim 13, wherein the first shape has a first height and the second shape has a second height and determining the location of the tip of the central venous catheter based on the comparison of the first and second shapes comprises concluding the tip of the central venous catheter is located in the right ventricle if the first height is at most half the second height.

16. The method of claim 13, wherein the first shape has a first height and the second shape has a second height and determining the location of the tip of the central venous catheter based on the comparison of the first and second shapes comprises concluding the tip of the central venous catheter is located in either the right atrium or superior vena cava if the first height is approximately equal to the second height.

17. The method of claim 12, wherein the portion of the central venous catheter disposed within the superior vena cava has a reference pair of electrodes, the method comprising:

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

generating a reference P wave from the reference signal; and

determining a second location of the tip of the central venous catheter based on the comparison of the first and reference P waves.

18. The method of claim 17, wherein the first P wave has a first shape and the reference P wave has a reference shape and comparing the first and reference P waves comprises comparing the first and reference shapes.

19. The method of claim 18, wherein determining the second location of the tip of the central venous catheter based on the comparison of the first and reference shapes comprises concluding the tip of the central venous catheter is located in the right ventricle if the first shape approximates a mirror image of the reference shape about a horizontal axis.

20. The method of claim 17, wherein the first shape has a first height and the reference shape has a reference height and determining the second location of the tip of the central venous catheter based on the comparison of the first and reference shapes comprises concluding the tip of the central venous catheter is located in the right atrium if the first height is at least twice the reference height.

21. The method of claim 17, wherein the first shape has a first height and the reference shape has a reference height and determining the second location of the tip of the central venous catheter based on the comparison of the first and reference shapes comprises concluding the tip of the central venous catheter is located in either the superior vena cava or right ventricle if the first height is approximately equal to the reference height.

22. The method of claim 12, wherein the portion of the central venous catheter disposed within the superior vena cava has a reference pair of electrodes, the method comprising, the method comprising:

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

generating a reference P wave from the reference signal; and

determining a second location of the tip of the central venous catheter based on the comparison of the second and reference P waves.

23. The method of claim 22, wherein the second P wave has a second shape and the second shape has a second height and the reference P wave has a reference shape and the reference shape has a reference height and determining the second location of the tip of the central venous catheter based on the comparison of the second and reference P waves comprises concluding the tip of the central venous catheter is located in the right atrium if the second height is at least twice the reference height.

24. A computer-readable medium having computer executable instructions for determining the location of a tip of a central venous catheter based on 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;

comparing the first deflection value to the second deflection value; and

determining a location of the tip of the central venous catheter based on the comparison of the first and second deflection values.

25. The computer-readable medium of claim 24, 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 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 comprise instructions for comparing the first ratio to a predetermined maximum threshold.

26. The computer-readable medium of claim 24, 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 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 comprise instructions for comparing the first ratio to a predetermined minimum threshold.

27. The computer-readable medium of claim 24, comprising instructions for obtaining a reference deflection value;

comparing one of the first and second deflection values with the reference deflection value; and

determining a second location of a tip of the central venous catheter based on the comparison of one of the first and second deflection values to the reference deflection value.

28. The computer-readable medium of claim 27, wherein the instructions for comparing one of the first and second deflection values to the reference deflection value comprise instructions for calculating a second ratio of one of the first and second deflection values to the reference deflection value and instructions for determining the second location of the tip of the central venous catheter based on the comparison of one of the first and second deflection values to the reference deflection value comprise instructions for comparing the second ratio to a predetermined maximum threshold.

29. The computer-readable medium of claim 24, wherein the first and second P waves comprise a series of discrete numerical values and the instructions for calculating the deflection value as a function of the P wave 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.