Method of monitoring a vascular access and an apparatus for extracorporeal treatment of blood with a device for monitoring the vascular access

• US 20010007930A1
• Filed: 01/31/2001
• Published: 07/12/2001
• Est. Priority Date: 10/20/1998
• Status: Active Grant

• Current Assignee: Wolfgang Kleinekofort
• Original Assignee: Wolfgang Kleinekofort
• Inventors: Kleinekofort, Wolfgang
• Granted Patent: US 6,595,942 B2
• Time in Patent Office: Days
• US Class Current: 604/4.01
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1692 Detection of blood traces in dialysate
• CPC Class Codes: A61M 1/36 Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
• CPC Class Codes: A61M 1/3621 Extra-corporeal blood circuits single-needle circuits A61M1/30
• CPC Class Codes: A61M 1/3639 Blood pressure control, pressure transducers specially adapted therefor
• CPC Class Codes: A61M 1/3656 Monitoring patency or flow at connection sites; Detecting disconnections
• CPC Class Codes: A61M 1/3693 using separation based on different densities of components, e.g. centrifuging
• CPC Class Codes: A61M 2205/13 with means for the detection of operative contact with patient, e.g. lip sensor
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/17 with redundant control systems
• CPC Class Codes: A61M 2205/18 with alarm

Abstract

A method and device for monitoring a vascular access during a dialysis treatment in which the pressures in both the arterial and venous branches of the extracorporeal blood system are monitored by pressure sensors. Characteristic values for the condition of the vascular access are calculated in a computer unit from the pressures in the arterial and venous branches of the extracorporeal system, and these values are analyzed in an analyzer unit to detect a defective vascular access.

Claims

1. Method of monitoring a vascular access during an extracorporeal blood treatment comprising the steps of:

(a) providing blood from the vascular access of a subject through an extracorporeal blood path comprising an arterial line in fluid communication with the vascular access, a blood treatment device, and a venous line in fluid communication with the vascular access;

(b) measuring fluid pressure within the arterial and venous lines; and

(c) calculating first and second characteristic values for the integrity of the vascular access from the measured arterial and venous pressures;

wherein the integrity of the vascular access is determined by comparing the first and second characteristic values to first and second ranges of predetermined values.

2. The method of

claim 1

, wherein step (c) further comprises the steps of:

(i) calculating the first characteristic value by calculating a sum of the measured pressure in the venous line and the measured pressure in the arterial line according to the equation;

P_S=P_VEN+P_ART; and

(ii) calculating the second characteristic value by calculating a difference between the measured pressure in the venous line and the measured pressure in the arterial line according to the equation;

Δ

P=P_VEN−

P_ART.

3. The method of

claim 3

, wherein successive measurements of the arterial and venous pressures are taken.

5. The method of

claim 5

, wherein step (c) further comprises the steps of:

(i) calculating a first characteristic value by adding the changes in the sum for a predetermined number of successive pressure measurements; and

(ii) calculating a second characteristic value by adding the changes in a predetermined number of calculated pressure differences.

4. The method of

claim 5

, wherein step (c) further comprises the steps of:

(i) calculating a change in the pressure sum for successive measurements by subtracting the sum for a first measurement from the sum for a second measurement; and

(ii) calculating a change in the pressure difference between successive measurements by subtracting the difference for a first measurement from the difference for a second measurement.

6. The method of

claim 6

, further comprising the step of generating a safe response in reaction to characteristic values selected from the group consisting of:

(i) a first characteristic value below the first range of values, and a second characteristic value below the second range of values, and

(ii) a first characteristic value above the first range of values, and a second characteristic value above the second range of values.

7. The method of

claim 7

, wherein the safe response is an alarm selected from the group consisting of visual and audible alarms.

8. The method of

claim 7

, wherein the safe response comprises closing a cutoff clamp in the venous line.

9. The method of

claim 7

, wherein the safe response comprises interrupting the provision of blood to the extracorporeal blood path.

10. The method of

claim 7

, wherein the safe response comprises stopping a blood pump provided in the arterial line.

11. A system for extracorporeal blood treatment comprising:

(a) an extracorporeal blood path comprising an arterial line in fluid communication with a first vascular access and an inlet to a blood treatment device, and a venous line in fluid communication with an outlet of the blood treatment device and with a second vascular access;

(b) an arterial fluid pressure sensor in communication with the arterial line and constructed and arranged for measuring pressure within the arterial line;

(c) a venous fluid pressure sensor in communication with the venous line and constructed and arranged for measuring pressure within the venous line;

(d) a computer unit connected to the arterial and venous pressure sensors, which is constructed and arranged for generating first and second characteristic values for the integrity of the vascular access from measured arterial and venous pressures;

(e) an analyzer unit constructed and arranged for analyzing the integrity of the vascular access by comparing the first and second characteristic values to first and second ranges of predetermined values.

12. The system of

claim 12

, wherein generating the first characteristic value includes calculating a sum of the measured pressure in the venous line and the measured pressure in the arterial line according to the equation P_S=P_VEN+P_ART, and generating the second characteristic value includes calculating a difference between the measured pressure in the venous line and the measured pressure in the arterial line according to the equation Δ

P=P_VEN−

P_ART.

16. The system of

claim 12

, wherein the analyzer unit is further constructed and arranged for generating a safe response in reaction to characteristic values selected from the group consisting of:

(i) a first characteristic value below the first range of values, and a second characteristic value below the second range of values, and

(ii) a first characteristic value above the first range of values, and a second characteristic value above the second range of values.

19. The system of

claim 16

, wherein the predetermined number of successive measurements is greater than a product of the frequency of arterial and venous pressure measurement and a value for the attenuation of the arterial and venous pressure sensors.

24. The system of

claim 12

, wherein the system is incorporated into a dialysis machine.

13. The system of

claim 13

, further comprising a memory unit connected to the computer unit, which is constructed and arranged for storing successive pressure sum and pressure difference values calculated by the computer unit and transmitting the stored values to the computer unit.

14. The system of

claim 14

, wherein generating the first characteristic value further includes calculating a change in the pressure sum for successive measurements by subtracting the sum for a first measurement from the sum for a second measurement, and generating the second characteristic value further includes calculating a change in the pressure difference between successive measurements by subtracting the difference for a first measurement from the difference for a second measurement.

15. The system of

claim 15

, wherein the first characteristic value is calculated by adding the changes in the sum of a predetermined number of successive measurements, and the second characteristic value is calculated by adding the changes in the predetermined number of calculated pressure differences.

17. The system of

claim 17

, wherein the smallest value in the first range of predetermined characteristic values (M₁) is less than the smallest value in the second range of predetermined characteristic values (M₂).

20. The method of

claim 17

, wherein the safe response is an alarm selected from the group consisting of visual and audible alarms.

21. The method of

claim 17

, wherein the safe response comprises closing a cutoff clamp in the venous line.

22. The method of

claim 17

, wherein the safe response comprises interrupting the provision of blood to the extracorporeal blood path.

23. The method of

claim 17

, wherein the safe response comprises stopping a blood pump provided in the arterial line.

18. The system of

claim 18

, wherein M₁ is −

15 mmHg and M₂ is −

10 mmHg.