Method and device for detecting the detachment of the venous needle from a patient during dialysis

• US 20040171977A1
• Filed: 12/24/2003
• Published: 09/02/2004
• Est. Priority Date: 06/29/2001
• Status: Active Grant

• Current Assignee: Gambro Lundia AB (Baxter International Inc.)
• Original Assignee: Gambro Lundia AB (Baxter International Inc.)
• Inventors: Paolini, Francesco Alberto, Lodi, Carlo Alberto, Fava, Massimo
• Granted Patent: US 7,648,474 B2
• Time in Patent Office: Days
• US Class Current: 604/4.01
• CPC Class Codes: A61M 1/3639 Blood pressure control, pressure transducers specially adapted therefor
• CPC Class Codes: A61M 1/3653 Interfaces between patient blood circulation and extra-corporal blood circuit
• CPC Class Codes: A61M 1/3656 Monitoring patency or flow at connection sites; Detecting disconnections
• CPC Class Codes: A61M 1/367 Circuit parts not covered by the preceding subgroups of group A61M1/3621
• CPC Class Codes: A61M 2039/1005 Detection of disconnection
• CPC Class Codes: A61M 2205/13 with means for the detection of operative contact with patient, e.g. lip sensor
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 5/16831 Monitoring, detecting, signalling or eliminating infusion flow anomalies low-level float-valves causing cut-off A61M5/40; indicating or recording presence, absence or direction of flow in general G01P13/0066

Abstract

A method of detecting the detachment of the venous needle from a patient during an extracorporeal blood treatment in a dialysis machine having an extracorporeal blood circuit provided with an arterial branch and a venous branch. The arterial pressure (Pa) is measured in the arterial branch and the venous pressure (Pv) is measured in the venous branch, and the determination is made of whether or not decreases of the arterial pressures (Pa) and venous pressures (Pv) are occurring during the dialysis treatment in normal conditions.

Claims

1. Method of detecting the detachment of the venous needle (13) from a patient (P) during an extracorporeal blood treatment in a dialysis machine (1) having an extracorporeal blood circuit (2) comprising an arterial branch (8) and a venous branch (10), the method comprising the steps of measuring the arterial pressure (Pa) in the arterial branch (8) and the venous pressure (Pv) in the venous branch (10), and determining whether or not decreases of the arterial pressures (Pa) and venous pressures (Pv) are occurring during the dialysis treatment in normal conditions.

2. Method according to claim 1, characterized in that the flow of blood (Qb) along the extracorporeal blood circuit (2) is measured, and in that a check is made to determine whether the blood flow (Qb) is essentially constant in a time interval in which the said decreases of arterial pressure (Pa) and venous pressure (Pv) have occurred.

3. Method according to Claim 2, characterized in that the value of the said decreases of the arterial pressure (Pa) and venous pressure (Pv) is evaluated.

4. Method according to claim 3, characterized in that a signal (SA) correlated with the sum of the decreases of arterial pressure (Pa) and venous pressure (Pv) is compared with an experimentally determined threshold value (TV).

5. Method according to claim 4, characterized in that an alarm signal (AS) is emitted when all the following conditions are present in the said time interval:

a decrease in arterial pressure. (Pa);

a decrease in venous pressure (Pv);

the signal (SA) correlated with the sum of the decreases of arterial pressure (Pa) and venous pressure (Pv) is greater than the said threshold value (TV); and

the flow (Qb) is essentially constant.

6. Method according to claim 5, characterized in that the said blood flow (Qb) is stopped in the said extracorporeal circuit (2) by means of the said alarm signal. (AS), to interrupt the dialysis treatment.

7. Method according to claim 5 or 6, characterized in that an acoustic warning device (29) is activated by means of the said alarm signal (AS).

8. Method according to one of claims 5 to 7, characterized in that a visual indicator (30) is activated by means of the said alarm signal (AS).

9. Device for detecting the detachment of the venous needle (13) from a patient (P) during an extracorporeal blood treatment in a dialysis machine (1) having an extracorporeal blood circuit (2) comprising an arterial branch (8) and a venous branch (10), the device (14) being characterized in that it comprises pressure detectors (16, 17) for measuring the arterial pressure (Pa) in the arterial branch (8) and the venous pressure (Pv) in the venous branch (10), and a control unit (15) for determining whether or not decreases of the arterial pressures (Pa) and venous pressures (Pv) are occurring during the dialysis treatment in normal conditions.

10. Device according to claim 9, characterized in that it comprises means (18) for measuring the flow (Qb) of blood along the extracorporeal blood circuit (2), the said control unit (15) comprising means (19r, 21) for determining whether the blood flow (Qb) is essentially constant.

11. Device according to claim 10, characterized in that the said determining means comprise a derivation unit (19r) for emitting a signal correlated with the derivative of the blood flow (Qb) and a first comparison unit (21) for determining whether the signal correlated with the derivative of the flow (Qb) falls within an interval (I) of acceptability.

12. Device according to Claim 10 or 11, characterized in that the said control unit (15Y comprises means (23, 24, 25) for discriminating the value of the decreases of the arterial pressure (Pa) and venous pressure (Pv).

13. Device according to claim 12, characterized in that the said control unit (15) comprises a logical operator unit (27) which can emit a control signal (SC) as a function of the decreases of arterial pressure (Pa) and venous pressure (Pv), the output signal from the second comparison unit (24), and the output signal from the first comparison unit (21).

14. Dialysis machine comprising a control device (14) according to any one of claims 9 to 13, characterized in that it comprises an additional control unit (28) which can receive a control signal (SC) from the said control unit (15) and emit an alarm signal (AS) as a function of the control signal (SC).

15. Machine according to claim 14, characterized in that it comprises a peristaltic pump (9) located in the said arterial branch (8), and a dropper (11) located in the said venous branch (10), the said peristaltic pump (9) being stoppable by means of the said alarm signal.

16. Machine according to claim 15,, characterized in that the said detectors (16, 17) comprise a first detector (16) located in the arterial branch (8) up-line from the peristaltic pump (9), and a second detectors (17) located in the venous branch (10) near the dropper (11).

17. Machine according to any one of claims 14 to 16, characterized in that the said additional control unit (28) comprises an acoustic warning device (29) which can be activated by means of the said alarm signal (AS).

18. Machine according to any one of claims 14 to 17, characterized in that the said additional control unit (28) comprises a visuals indicator (30) which can be activated by means of the said alarm signal.