Device for monitoring an infusion pump

ES 2 227 751 T3

DESCRIPTION

Device for monitoring an infusion pump. Technical field

The present invention relates to a machine for hemodiafiltration or hemofiltration. More particularly, the invention relates to such a machine with means for calibrating the infusion pump.

Background of the invention

A conventional type of hemodialysis machine is marketed under the trade name GAMBRO AK 200 ULTRA and is adapted to perform hemodialysis, hemodiafiltration or hemofiltration treatment.

The dialysis machine prepares a solution comprising sodium-, bicarbonate- potassium-, calcium-, magnesium-, chloride-, and acetate ions in suitable concentrations, as well as possibly glucose and other ions, all dissolved in water. The concentrations of the ions in the dialysis solution are generally mirror images of the blood concentrations, where the mirror line is the normal blood concentration of the ions. Thus, if an ion concentration in the blood is increased above the normal concentration, the ion concentration in the dialysis solution decreases relative to the normal concentration. The pH of the solution is adjusted to around 7.1-7.4.

In hemodialysis treatment, the solution is used to achieve dialysis in a dialyzer. The dialyzer is divided into two chambers by means of a semi-permeable membrane. The blood to be treated passes over one side of the membrane while the dialysis solution prepared by the dialysis machine passes over the other side. Ion diffusion takes place across the membrane to condition the blood and replace kidney function, at least partially. Furthermore, a quantity of fluid is withdrawn from the blood since the patient is unable to get rid of the excess fluid in a normal way. The withdrawn liquid that flows through the membrane is called ultrafiltration flux.

During hemodiafiltration, the ultrafiltration flow is increased above what is necessary to restore the patient's fluid balance. As a replacement, an infusion solution is added to the blood to allow increased ultrafiltration flow.

During hemofiltration, substantially no dialysis takes place, although instead the blood is filtered, whereby a part of the ultrafiltration volume is added to the blood as an infusion solution. The difference between the ultrafiltration volume and the added replacement volume is the volume of fluid that is removed from the patient to restore fluid balance. The infusion solution can be added upstream of the dialyzer or hemofilter in a procedure called "pre-infusion", or downstream of the dialyzer or hemofilter in a procedure called "post-infusion."

To effect the infusion flow, the dialysis machine comprises an infusion pump connected to an outlet for infusion solution on the dialysis machine. The infusion solution is normally the same as the dialysis solution. The infusion solution passes through the infusion pump and a sterile filter and is then fed into the patient's blood. The infusion pump may be a so-called peristaltic pump, as used in the GAMBRO AK 200 ULTRA dialysis machine mentioned above.

Before treatment, the dialysis machine is provided with a set of tubes, the constituent components of which must be filled with liquid so that all the air is expelled. This normally takes place in a priming stage during which the sterile sodium chloride solution is fed into various tubes and components of the tube set. The conduit system of the dialysis machine is also filled with dialysis solution.

During the priming of the infusion circuit, a specific deaeration duct of the sterile filter is used so that the filter is completely filled with priming liquid so that the air is expelled. The nurse uses forceps or a tube clamp which is placed over the normal exit conduit from the sterile filter and thereby interrupts the flow through it. In addition, a tube clamp is opened on the deaeration conduit of the sterile filter, the nurse removes the forceps from the outlet conduit or opens the tube clamp, as well as closes the tube clamp over the deaeration conduit, and priming continues. .

Due to the human factor, the nurse may forget to remove the forceps or open the tubing clamp, which may result in the infusion not taking place. This can have serious consequences for treatment if it is not corrected.

The infusion pump can be a peristaltic pump which is operated at a predetermined speed or number of revolutions so that the desired infusion flow or volume is achieved. However, a peristaltic pump is pressure sensitive at the inlet and it may be desirable to calibrate the pump for the particular treatment and / or verify whether the desired infusion volume has actually been achieved at a particular rotational speed of the peristaltic pump.

A peristaltic pump can leak due to the fact that the pump segment occlusion is not complete, which can result in zero flow.

Furthermore, problems can arise if the user installs a set of tubes which are not intended for the dialysis machine in question, for example a counterfeit copy, which may not provide adequate infusion flow.

It may also be desirable to indicate if all the air in the sterile filter has been completely expelled during priming, or if there is a blockage or leak in the sterile filter.

An object of the present invention is to provide a machine to allow the detection of the above-mentioned operational failures.

A further object is to provide a machine of the aforementioned type in which substantially only the components that normally form a part of a dialysis machine are used.

Accordingly, there is provided a machine according to claim 1. With the machine, the infusion pump can be calibrated with reference to the flow meter.

In a preferred embodiment, the flowmeter is constructed as a dual flowmeter having inlet and outlet flow measurement portions configured such that the inlet flow portion of the flowmeter is connected in series with

ES 2 227 751 T3 the infusion pump. Alternatively, the flow meter may comprise an ultrafiltration metering pump.

According to another alternative, the flow in the first flow circuit can bypass the dialyzer or hemofilter via a bypass conduit, so that the flowmeter determines the difference between the inflow and the outflow in the first flow circuit.

Claims 2-5 define preferred embodiments of the invention.

Additional objects, features, advantages and properties of the machine according to the invention will become apparent from the following description of the preferred embodiments of the invention with reference to the accompanying drawings.

Brief description of the drawings

Fig. 1 is a schematic diagram of a dialysis machine of conventional structure in which the invention can be applied.

Fig. 2 is a diagram corresponding to fig.

modified according to a first embodiment of the invention.

Fig. 3 is a diagram according to fig. 1 modified according to a second embodiment of the invention.

Fig. 4 is a schematic diagram corresponding to FIG. 1 modified according to a third embodiment of the invention in which the invention is applied to a dialysis machine with a different ultrafiltration pump.

Detailed description of the preferred embodiments

Fig. 1 shows a schematic diagram of a part of a dialysis machine, for example of the GAMBRO AK 200 ULTRA type.

The dialysis machine in fig. 1 comprises an inlet 1 for pure water, normally obtained from an RO unit. Furthermore, a preparatory unit is available for the desired composition dialysis solution of one or more concentrates indicated by arrows 3, 4 and 5. The preparatory unit is conventional and thus will not be described in more detail.

A pump 6 feeds the dialysis solution via a flow meter 7 and via a first conduit 8 to a first filter 9. The filter 9 is a filter which is used for multiple treatments and has a large surface area. The filter 9 passes substances, molecules and ions below a certain predetermined size, for example below a diameter of 5 nm.

The filtered dialysis solution flows along a conduit 10 to an outlet 11 from which an infusion solution can be withdrawn. A conduit 12 extends from the outlet 11 to a butterfly valve 13 which ensures that the pressure upstream of the butterfly valve is substantially constant, for example +50 mmHg. A conduit 14 extends from the butterfly valve 13 to a three-way valve 15 and further via a tube 16 to a dialyzer 17. A conduit 18 extends from the dialyzer 17 to the valve 19. A conduit 20 extends from the valve 19 back to the flow meter 7. The dialysate flows through the flow meter and via a pump 21 and additional devices 22 to an outlet 23 .

The flowmeter 7 consists of two portions or channels 46 and 47 so that the flow in and out can be measured separately. Furthermore, an exact value of the difference between the incoming and outgoing flow is obtained, the difference of which normally corresponds to the ultrafiltrate flow which is withdrawn in the dialyzer 17.

A conduit 24 extends from filter 9 via valve 25 to outlet 26.

A bypass conduit 27, which bypasses dialyzer 17, extends between valves 15 and 19.

A conduit 28 extends from outlet 11 to a peristaltic pump 29 and further via conduit 30 to a sterile filter 31. A conduit 32 for deaeration of the sterile filter is connected to the other end of the sterile filter. In addition, a conduit 33 is provided which extends from the sterile filter to a discharge chamber 34. The sterile filter 31 is normally used once and is sterilized before use.

The dialysis machine also comprises an extracorporeal flow circuit for blood. From, for example, a fistula located in the patient's arm 35, blood is withdrawn from the body via an artery needle 36 which, via conduit 37 and a peristaltic pump 38, extends to the lower end of dialyzer 17. From the upper end of the dialyzer, the treated blood is transferred via a conduit 39 to the discharge chamber 34 where it is de-aerated and returns to the patient via a conduit 40 and a venous needle 41.

The above-described flow circuit is a conventional flow circuit arranged for post-infusion. Alternatively, conduit 33 as shown by dashed line 41 may be connected to an entry point 42 between pump 38 and dialyzer 17 to thereby achieve pre-infusion.

When the dialysis machine is operated for hemofiltration treatment, valve 15 is changed so that line 16 is disconnected and dialyzer 17 is connected to the dialysis machine only via line 18. In this case, the dialyzer 17 is replaced by a hemofiltrator, which does not have a connector for conduit 16.

The dialysis machine comprises a computer 70 adapted to monitor and check the operation of the different components of the machine. In this way, the computer operates the valves and pumps, and receives signals from the valves and pumps that indicate their positions and conditions, as well as signals from the various calibration devices.

During the priming of the sterile filter 31, a nurse closes a conventional tube clamp 43 on the tube 33 as shown in FIG. 1 and opens a conventional tube clamp 44 over the deaeration conduit 32. The dialysis solution that is pumped by pump 29 will thereby pass through sterile filter 31 and fill it with liquid, as well as expel air in the filter via deaeration conduit 32, which opens to atmosphere. When all the air has been expelled, the tube clamp 44 closes and the tube clamp 43 in the duct 33 opens and any air that may remain in the filter and duct 33 passes via duct 33 into the chamber 34 of download.

There are a number of errors that would be desirable to detect in such a system.

For example, the nurse may forget to open the tube clamp 43 on the conduit 33 so that it locks at the same time that the tube clamp 44 is closed on the conduit 32. If this happens, the peristaltic pump 29 cannot pump any.

ES 2 227 751 T3 infusion solution or liquid, so that no infusion solution reaches the patient.

As a further example, if the sterile filter is not completely airless, the infusion flow may also be low. If filter blockage or leakage arises, the situation needs to be remedied.

It is also desirable to be able to calibrate the infusion pump 29 during treatment, or at least at the beginning of treatment.

It is also desirable to detect a leak in the pump because the pump segment is not completely occluded.

It is still desirable to detect if an unsuitable tubing set is used as it can result in a malfunction with resulting erroneous infusion flow.

All of these malfunctions can be detected by the invention as described below. It will be understood by the person skilled in the art that the operation according to the invention can be controlled and monitored by the computer 70 of the dialysis machine.

According to an embodiment of the invention, a shut-off valve 50 is added to the flow circuit according to fig. 1 in conduit 14, as shown in FIG. 2. By means of said shut-off valve 50 and valve 19, the dialyzer 17 or the hemofilter can be disconnected from the dialysis circuit. Conduit 20 and pump 21 will thereby receive zero flow.

The flow that passes through the inlet channel 46 of the flowmeter 7 via the conduit 8 and 10 and reaches the outlet 11 must pass via the infusion circuit, that is, the conduit 28, the pump 29, the conduit 30 and the filter. 31 infusion and conduit 33 to discharge chamber 34. By adjusting the dialysis machine to operate in this way, the infusion pump 29 can be calibrated against the inlet channel 46 of the flowmeter 7.

If something could reduce the flow through the infusion circuit, this will be immediately detected by the flow meter 7 showing zero flow despite the fact that the peristaltic pump 29 is rotating. In this way, any improper priming can be detected and identified with the tube clamps closed.

Possible leakage in pump 29 due to poor occlusion may cause the flow through pump 29 to be too high or too low compared to the expected flow, which can also be detected by flowmeter 7. In this case, the flowmeter 7 will show a higher value than expected in the rotational speed of the peristaltic pump 29, since there is normally a positive pressure at the outlet 11.

In the same way, an unsuitable tubing assembly, a sterile filter filled with air, or blockage or leakage in the sterile filter can be detected as a difference between the actual measured flow through the flowmeter based on the expected flow in the turn of the bomb.

All of these conditions can be detected by the dialysis machine computer 70 and the computer can be programmed to take appropriate actions.

An alternative embodiment of the present invention is shown in fig. 3. Valve 50 in conduit 14 according to the embodiment shown in FIG. 2 has been replaced by a valve 51 arranged in conduit 18. When activated, valve 51 closes conduit 18.

When the calibration of the infusion pump 29 with the machine according to the invention is to take place, the valve 15 is switched to its second position and the valve 51 is activated to its second position. In this way, the dialyzer 17 is completely disconnected. Flow in the dialysis circuit takes place via bypass conduit 27. Flowmeter 7 verifies that inlet 46 and outlet 47 flows are equal.

If, however, the infusion pump 29 operates at a predetermined rate, for example to achieve an expected flow rate of 50 ml / min, the inflow flow 46 through conduit 8 will be greater than the outflow through duct 20, which is measured by flow meter 7. In this way, the infusion pump 29 can be calibrated with the help of the flow meter 7 by the difference between the inlet and outlet flows in the same way as when ultrafiltration was measured. However, the difference that is measured with the machine according to the invention will be in the other direction, which, however, does not create any kind of problems.

A pressure gauge 45 can be connected to outlet 11. Pressure gauge 45 ensures that conditions at outlet 11 remain the same during operation regardless of whether the dialysis machine is connected for calibration of infusion pump 29 .

Fig. 4 shows the present invention instrumented according to another type of dialysis machine in which the ultrafiltration is removed using a specific ultrafiltration pump 61 and in which the flowmeter 7 is regulated so that the incoming flow is always the same as the flow output.

Ultrafiltration pump 61 is connected to conduit 20 via conduit 62. The ultrafiltration volume passes through pump 61 and via conduit 63 to outlet 64. Furthermore. a chamber 65 is arranged in the duct 63 and is provided with a level regulator 66, 67. According to this embodiment of the invention, the valve 51 according to fig. 3.

When the dialysis machine according to fig. 4 is to be used to calibrate the infusion pump 29, valve 15 is switched to its second position and valve 51 is closed so that the dialysis flow passes from circuit 14 to bypass line 27 and further to line 20. In this way, the dialyzer 17 or the hemofilter is isolated from the dialysis circuit. The ultrafiltration pump 61 must be stopped since the identical flows pass through the inlet and outlet ducts of flowmeter 7.

As described above, a chamber 65 is connected to conduit 63 and contains a volume of about 50 ml or more. When infusion pump 29 is calibrated, pump 61 reverses at the same time as pump 29 starts. The contents in chamber 65 are pumped along conduit 20 at the same time as pump 29 operates. Thus, the flow that exits through infusion pump 29 must be as great as the flow that enters via pump 61 into conduit 20. The flow through dialysis circuit 8, 10, 14, 27, 20 it occurs with, for example, 500 ml / min and with equal flows through the inlet 46 and outlet 47 ducts or channels.

In this way, the infusion pump 29 is calibrated against the inverted ultrafiltration pump 61. The solution in chamber 65 is thus called dirty solution received from dialyzer 17. This solution, however, will be pumped

ES 2 227 751 T3 inside conduit 20 and then will flow through flowmeter 7 to outlet 23 and thus does not affect the clean side of the dialysis circuit in conduits 8, 10 and 14.

If it is not possible to reverse the ultrafiltration pump, a valve pack can be provided in its place which ensures that the pump flow is reversed.

Calibration with a machine according to the invention is preferably carried out at the beginning of a treatment during the priming stage. During this first calibration, it can be established whether the flow through conduit 28 is too small, in which case an alarm signal is issued.

It is also possible to calibrate the infusion pump 29 during operation of the dialysis machine. Typically, a self-calibration of the dialysis machine occurs approximately every thirty minutes during the entire dialysis procedure. The machine according to the present invention can be used for such a calibration. If the embodiment according to fig. 2, pump 21 is connected via line 20, valve 19, and line 18 to dialyzer 17. In this way, pump 21 can ensure that an underpressure prevails in dialyzer 17 which allows ultrafiltration to take place continuously even during calibration. In this embodiment, the infusion pump 29 is calibrated with respect to the inlet channel 46 of the flowmeter 7.

If the embodiment according to fig. 3, the dialyzer 17 is completely isolated from the dialysis machine and ultrafiltration does not take place. However, an infusion of infusion solution into the blood occurs and the liquid is thus delivered to the patient. However, the infusion solution supplied is of relatively small volume, on the order of 50 ml, which can easily be compensated for by the increase in ultrafiltration immediately after the calibration step.

It should be understood that the invention can be implemented according to dialysis machines having different conduit paths than those offered above. For example, it is possible to implement the invention as a dialysis machine that lacks the filter 9.

The invention has been described above with reference to the preferred embodiments represented in the drawings. A person skilled in the art recognizes that these embodiments can be modified and instrumented according to different dialysis machines without departing from the invention. The invention is limited only by the appended claims.