METHOD FOR CONVEYING A MEDIUM WITH A PUMP AND PUMP COMPRISING A ROTOR, A HOUSING AND A DRIVE

Abstract

A method for conveying blood or priming liquid as a medium using a blood pump, measures gas in the medium in a feed line to the pump, in or on the pump, and the pump power is increased only for a short time as a function of the measured gas. A blood pump, in particular a centrifugal pump or diagonal pump, includes a rotor, a housing and a drive, the pump including a gas detector which acts upon the drive when gas is detected.

Claims

1. Method of conveying blood or priming fluid as medium with a blood pump (1), in which gas (25) is measured in the medium (5) in an inlet line to the pump, in or on the pump and the pump output is increased only briefly as a function of the measured gas.

2. Method according to claim 1 wherein the pump (1) is a centrifugal pump or a diagonal pump.

3. Method according to claim 1, wherein the pump output is increased for a period of less than 5 seconds and preferably from 0 to 2 seconds, more particularly from 0.1 to 2 seconds.

4. Method according to claim 1, wherein the pump output is increased by up to 100% within a period of less than 5 seconds and preferably 0 to 2 seconds, more particularly from 0.1 to 2 seconds

5. Method according to claim 1, wherein the pump output is reduced before the increase.

6. Method according to claim 1, wherein before the increase the pump output is reduced by up to 100% within a period of less than 5 seconds and preferably 0 to 2 seconds, more particularly from 0.1 to 2 seconds.

7. Method according to claim 1, wherein the pump output is increased on detection of gas entry.

8. Method according to claim 1, wherein the pump output is increased after the detection of a predetermined gas quantity.

9. Method according to claim 1, wherein the pump output is increased after a period of time corresponding to the time required by the medium (5) to travel from the detector (16) to the rotor (3) of the pump (1).

10. Method according to claim 1, wherein the pump output is increased on expiry of a predetermined period of time following the first gas entry (e.g. period or time greater than 3 seconds).

11. Method according to claim 1, wherein the pump output is pulsed over a period or more than 3, preferably more than 5 seconds.

12. Method according to claim 1, wherein the pump (1) is operated in a pulsatile manner during priming.

13. Method according to claim 1, wherein the gas (25) is detected in that the power uptake of the pump (1) is measured in relation to its power output.

14. Method according to claim 1, wherein the gas (25) is detected in that the temperature on the bearing (10, 11) of the rotor is measured.

15. Blood pump (1), in particular centrifugal pump or diagonal pump, with a rotor (3), a housing (6) and an actuator (7) wherein it comprises a gas detector (16, 21, 23) which acts on the actuator (7) when gas (25) is detected.

16. Blood pump according to claim 15, wherein the detector (16) is arranged in an inlet line (2) to the pump (1).

17. Blood pump according to claim 15, wherein the detector (21) is arranged in or on the housing (6) of the pump (1).

18. Blood pump according to claim 15, wherein the detector (23) is arranged on the rotor (3) or on the rotor bearing (10, 11).

19. Blood pump according to claim 15, wherein the detector (16, 21) is a contactlessly measuring sensor.

20. Blood pump according to claim 15, wherein the sensor of the detector (16, 21, 23) does not send a signal during the conveying of the medium (5) and sends a signal in the event of air entry.

Description

[0028] Various embodiments of blood pumps according to the invention are shown in the drawing and will be described in further detail below.

[0029] FIG. 1 schematically shows a pump head with a controller,

[0030] FIG. 2 schematically shows a view from above of the pump head shown in FIG. 1 and

[0031] FIG. 3 schematically shows cross-section through the pump head shown in FIG. 1.

[0032] The pump 1 shown in FIG. 1 is a diagonal pump as the conveyed medium emerges from the rotor obliquely to the pump shaft. Depending on the design of the pump the conveying angle of the rotor can be varied so that the pump can be designed in the complete spectrum from radial to axial in order to be adapted to the application in question. However, the pump 1 has a predominantly radial conveying part for conveying blood entering centrally at the inlet 2 by means of the rotor 3 to the outlet 4.

[0033] The blood 5 flows through the housing 6 while an actuator 7 act contactlessly on magnets 8, 9 of the rotor 3 in order to move the rotor 3. The rotor 3 is borne with a ball 10 or a pin 11. Arranged in the pin 11 is a metal cone 12 which dissipates the heat from the ball 10 to the base surface 13 of the housing.

[0034] The blood inlet 2 forms the supply line 14 which in the present case is also designed as a hose 15. Provided as the detector on this hose 15 is a capacitive switching sensor. This capacitive switching sensor 16 is connected via a line 17 to a pump control 18 which in turn is connected via a line 19 to the actuator 7 of the rotor 3. The control 18 also comprises a further line 20 to report the values of the controller to a higher-ranking device (not shown) and to receive regulation and control parameters therefrom. This controller is provided in a pump console for example.

[0035] An optional further capacitive switching sensor 21 measures, as the detector, air entry at the pump housing in order to report this via line 22 to the controller 18.

[0036] Acting as a third optional detector is a temperature measuring device 23 on the base surface 13 of the housing 6 which measures the temperature on the bearing 10, 11 by detecting the temperature on the metal cone 12. This value can also be passed on to the controller 18 via a line 24.

[0037] If a gas bubble 25 enters the housing 6 of the blood pump 1 along with the medium, which in the present case is blood 5, this gas bubble 25 can already be detected by the detector 16 while it is travelling though the hose 15. Another opportunity of discovering this gas bubble 15 is provided by the further capacitive switching sensor 21. If gas bubbles accumulate centrally in the area of the axis of the bearing of the rotor 3 the pump output decreases which can be detected by the controller 18. In addition, the temperature at the bearing changes which is determined with the temperature measuring device.

[0038] In the present case air can accumulate between the pin 11 and the inner area of the rotor 3 which can be determined by means of a capacitive sensor. An air bubble trapped there can be become trapped in such a way that is can no longer be conveyed to the outlet 4.

[0039] If a pulsatile mode or blood flow is now switched on by means of the controller 18 on the actuator 7, in the brief moment of reduced flow the air has the possibility of becoming detached from the rotor. The subsequent thrust then conveys the air bubble out of the pump through the blood outlet 4. In this way the blood pump is again cleared of air. Advantageous is a reduction over 0.1 to 2 seconds and then an increase over 0.1 to 2 second for total pulsatile operation duration of approximately 5 to 30 seconds.

[0040] In practice in the line (not shown) leading from the outlet 4 to the patient there is already a flow sensor with an integrated bubble detector, for example a clamp-on transducer IPX4. In order not to endanger the patient this sensor should continue to be positioned towards the patient. A second sensor can then be positioned directly in front of the pump 1. If this detects an air bubble the system can generate a firmly set pulsatility to convey air at the rotor out of the housing. As a rule the blood with the air is then forwarded to an oxygenator where the air can finally escape. In the example of embodiment the pulsatility for expelling the air is set to 10 seconds.

[0041] As an alternative to a clamp-on sensor provided in the inlet line a capacitive sensor 16 can be positioned on the surface of the pump housing. Such capacitive switches detect the change in the dielectric constant and convert this change into a switching signal. If, for example, there is air in the area of the rotor for more than 5 seconds a pulsatile operation of the pump 1 can be carried out for example. The switching function should be such that sensor is active in the event of air and off in normal operation (switching function Opener YES). This counteracts the risk of the sensor pulsating continuously in the event of a defect.