METHOD OF LOCATING THE TIP OF A CENTRAL VENOUS CATHETER

• US 20090259124A1
• Filed: 04/21/2009
• Published: 10/15/2009
• 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 8,388,546 B2
• Time in Patent Office: Days
• US Class Current: 600/424
• 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 5/063 using impedance measurements
• 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 5/25 Bioelectric electrodes therefor
• 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

Abstract

Methods of locating a tip of a central venous catheter (“CVC”) relative to the superior vena cava, sino-atrial node, right atrium, and/or right ventricle using electrocardiogram data. The CVC includes at least one electrode. In particular embodiments, the CVC includes two or three pairs of electrodes. Further, depending upon the embodiment implemented, one or more electrodes may be attached to the patient'"'"'s skin. The voltage across the electrodes is used to generate a P wave. A reference deflection value is determined for the P wave detected when the tip is within the proximal superior vena cava. Then, the tip is advanced and a new deflection value determined. A ratio of the new and reference deflection values is used to determine a tip location. The ratio may be used to instruct a user to advance or withdraw the tip.

Claims

1. A method of determining a location of a tip of a central venous catheter having a lumen filed with an electrolytic material, a portion disposed inside the superior vena cava, and a first electrode in communication with the electrolytic material, the tip having an opening in communication with the lumen that exposes the electrolytic material inside the lumen to the electrical environment outside the tip, the method comprising:

attaching a second electrode to the skin of a subject,

positioning the tip of the central venous catheter within the superior vena cava;

while the tip is positioned within the superior vena cava, obtaining a reference electrical signal comprising the voltage difference between the first electrode and the second electrode;

generating a reference P wave from the reference electrical signal;

determining a reference deflection value of the reference P wave;

one of advancing and withdrawing the tip of the central venous catheter to a new position;

while the tip is in the new position, obtaining a new electrical signal comprising the voltage difference between the first electrode and the second electrode;

generating a new P wave from the new electrical signal;

determining a new deflection value of the new P wave;

calculating a ratio of the new deflection value to the reference deflection value;

comparing the ratio to a threshold value; and

one of advancing or withdrawing the tip based on the comparison of the ratio to the threshold value.

2. The method of claim 1, wherein the one of advancing or withdrawing the tip based on the comparison of the ratio to the threshold value comprises:

advancing the tip if the ratio is less than the threshold value; and

withdrawing the tip if the ratio is greater than the threshold value.

3. The method of claim 1, wherein the threshold value is less than a ratio of a deflection value of a P wave detectable near the sino-atrial node to the reference deflection value.

4. The method of claim 1, further comprising:

if the ratio is equal to the threshold value, maintaining the tip of the central venous catheter in its current position.

5. The method of claim 1, further comprising:

if the ratio is greater than the threshold value, comparing the ratio to a second threshold value, and

if the ratio is greater than the second threshold value, determining the tip of the central venous catheter is in the right atrium and withdrawing the tip.

6. A method of determining a location of a tip of a central venous catheter having a lumen filed with an electrolytic material, a portion disposed inside the superior vena cava, a second electrode attached to the skin of a subject, and a first electrode in communication with the electrolytic material, the tip having an opening in communication with the lumen that exposes the electrolytic material inside the lumen to the electrical environment outside the tip, the method comprising:

obtaining a reference electrical signal comprising the voltage difference between the first electrode and the second electrode;

generating a reference P wave from the reference electrical signal;

determining a reference deflection value of the reference P wave;

after the tip of the central venous catheter has been moved to a new position, obtaining a new electrical signal comprising the voltage difference between the first electrode and the second electrode;

generating a new P wave from the new electrical signal;

determining a new deflection value of the new P wave;

calculating a ratio of the new deflection value to the reference deflection value;

comparing the ratio to a threshold value; and

indicating the tip should be withdrawn based on the comparison of the ratio to the threshold value.

7. A method of determining in which portion of the atrium a tip of a central venous catheter is located, the method comprising:

obtaining an electrical signal from a portion of the atrium adjacent the tip of the central venous catheter;

generating a P wave from the electrical signal;

determining a greatest positive deflection value for the reference P wave;

determining a smallest negative deflection value for the reference P wave;

calculating a ratio of the greatest positive deflection value to the smallest negative deflection value;

comparing the ratio to a first threshold value;

if the ratio is less than the first threshold value, determining the tip is in the upper atrium;

comparing the ratio to a second threshold value;

if the ratio is greater than the second threshold value, determining the tip is in the lower atrium; and

if the ratio is greater than or equal to the first threshold value, and the ratio is less than or equal to the second threshold value, determining the tip is in the mid atrium.

8. A computer-readable medium storing computer executable instructions for directing a processor to:

obtain a reference deflection value from a reference electrical signal detected near a tip of a central venous catheter when the tip was located in a first position inside the superior vena cava;

obtain a new deflection value from a new electrical signal detected near the tip of a central venous catheter after the tip was relocated from the first position to a second position;

calculate a ratio of the new deflection value to the reference deflection value;

compare the ratio to a threshold value;

if the ratio is less than the threshold value, signal to a user the tip may be advanced; and

if the ratio is greater than the threshold value, signal to the user to withdraw the tip.

9. A method of determining a location of a tip of a central venous catheter having an electrode disposed inside the venous system of a subject, the venous system of the subject comprising a superior vena cava having a proximal portion near a sino-atrial node, the method comprising:

positioning the tip of the central venous catheter within the venous system of the subject proximal to or within a proximal portion of the superior vena cava;

while the tip is positioned proximal to or within a proximal portion of the superior vena cava, generating a reference P wave using the electrode;

determining a reference deflection value of the reference P wave;

one of advancing and withdrawing the tip of the central venous catheter to a first position;

while the tip is in the first position, generating a first P wave using the electrode;

determining a first deflection value of the first P wave;

calculating a first ratio of the first deflection value to the reference deflection value;

one of advancing and withdrawing the tip of the central venous catheter to a second position,

while the tip is in the second position, generating a second P wave using the electrode;

determining a second deflection value of the second P wave;

calculating a second ratio of the second deflection value to the reference deflection value;

comparing the first ratio to the second ratio;

if the second ratio is less than the first ratio, withdrawing the tip of the central venous catheter until a P wave generated using the electrode has a minimum negative deflection value that is greater than a predetermined portion of the second deflection value of the second P wave; and

if the second ratio is greater than the first ratio, determining whether the second ratio exceeds a maximum threshold value, if the second ratio does not exceed the maximum threshold value, advancing the tip of the central venous catheter and if the second ratio exceeds the maximum threshold value, withdrawing the tip of the central venous catheter.

10. The method of claim 9, further comprising:

after each time the tip of the central venous catheter is advanced or withdrawn, generating a new P wave using the electrode, determining a new deflection value of the new P wave, and determining a new ratio of the new deflection value to the reference deflection value;

identifying a maximum ratio using the new ratio determined after each time the tip of the central venous catheter is advanced or withdrawn;

if the second ratio is less than the first ratio, after the tip of the central venous catheter has been withdrawn until the minimum negative deflection value is greater than the predetermined portion of the second deflection value of the second P wave, the tip is located in a current location, generating a current P wave using the electrode, determining a current deflection value of the current P wave, and determining a current ratio of the current deflection value to the reference deflection value; and

determining whether the current ratio is approximately equal to the maximum ratio and if the current ratio is approximately equal to the maximum ratio, maintaining the tip of the central venous catheter in its present location.

11. The method of claim 10, further comprising:

if the current ratio is not approximately equal to the maximum ratio, advancing the tip of the central venous catheter.

12. The method of claim 9, wherein the predetermined portion of the P wave is greater than three quarters of the total P wave.

13. The method of claim 9, wherein the predetermined portion of the P wave is greater than seven eighths of the total P wave.

14. The method of claim 9, further comprising:

if the second ratio is approximately equal to the maximum threshold value, maintaining the tip of the central venous catheter in its present location.

15. The method of claim 9, further comprising:

after each time the tip of the central venous catheter is advanced or withdrawn, generating a new P wave using the electrode, determining a new deflection value of the new P wave, and determining a new ratio of the new deflection value to the reference deflection value;

identifying a maximum ratio using the new ratio determined after each time the tip of the central venous catheter is advanced or withdrawn;

one of advancing and withdrawing the tip to a current location;

generating a current P wave using the electrode;

determining a current deflection value of the current P wave;

determining a current ratio of the current deflection value to the reference deflection value; and

determining whether the current ratio is approximately equal to the maximum ratio and if the current ratio is approximately equal to the maximum ratio, maintaining the tip of the central venous catheter in its present location.

16. A method of determining a location of a tip of a central venous catheter having an electrode disposed inside the venous system of a subject, the venous system of the subject comprising a superior vena cava having a proximal portion near a sino-atrial node, the method comprising:

at least one of advancing and withdrawing the tip the central venous catheter;

after each advancement or withdrawal of the tip of the central venous catheter, generating a new P wave using the electrode, determining a new deflection value of the new P wave, and determining a new ratio of the new deflection value to the reference deflection value;

identifying a maximum ratio using the new ratio determined after each advancement or withdrawal of the tip of the central venous catheter;

one of advancing and withdrawing the tip to a current location;

generating a current P wave using the electrode;

determining a current deflection value of the current P wave;

determining a current ratio of the current deflection value to the reference deflection value;

determining whether the current P wave has a minimum negative deflection value that is greater than a predetermined portion of the current P wave; and

determining whether the current ratio is approximately equal to the maximum ratio and if the current ratio is approximately equal to the maximum ratio, maintaining the tip of the central venous catheter in its present location.

17. The method of claim 16, further comprising:

determining whether the current ratio exceeds a maximum threshold value, if the current ratio does not exceed the maximum threshold value, advancing the tip of the central venous catheter and if the current ratio exceeds the maximum threshold value, withdrawing the tip of the central venous catheter.

18. A monitor electrically couplable to an electrode attached to a tip of a central venous catheter that is insertable into a venous system of a subject, the monitor comprising:

a processor;

a withdraw indicator coupled to the processor configured to indicate when the tip of the central venous catheter should be withdrawn; and

a memory coupled to the processor and having instructions executable by the processor, when executed, the instructions instructing the processor to;

store an identifier identifying the subject,

determine and store a reference deflection value of a P wave detected by the electrode attached to the tip of the central venous catheter,

associate the reference deflection value with the identifier identifying the subject,

determine a current deflection value of a current P wave detected by the electrode attached to the tip of the central venous catheter,

calculate a current ratio of the current deflection value to the stored reference deflection value, and

actuate the withdraw indicator to indicate the tip of the central venous catheter should be withdrawn based on the current ratio.

19. The monitor of claim 18, wherein the instructions executable by the processor further instruct the processor to:

store a maximum ratio comprising a largest ratio of the current deflection value to the stored reference deflection value calculated for the subject,

associate the maximum ratio with the identifier identifying the subject,

compare the current ratio to the maximum ratio, and

actuate the withdraw indicator to indicate the tip of the central venous catheter should be withdrawn based on the comparison.

20. The monitor of claim 18, wherein the instructions executable by the processor further instruct the processor to compare the current ratio to a threshold value and actuate the withdraw indicator to indicate the tip of the central venous catheter should be withdrawn based on the comparison.

21. The monitor of claim 18, wherein the instructions executable by the processor further instruct the processor to store at least one of the current deflection value and the current ratio.