Flushing system

A flushing system for a catheter, in particular for a catheter of a catheter pump, comprising a supply line having a pump section, a discharge line having a pump section and a pump, wherein the diameter of the pump section of the discharge line is smaller than the diameter of the pump section of the supply conduit, the pump interacts with the pump section of the supply line for supplying flushing fluid to the catheter, and the pump interacts with the pump section of the discharge line for discharging flushing fluid from the catheter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. 10 2017 102 829.3 filed on Feb. 13, 2017, and to PCT Application No. PCT/EP2018/051053 filed on Feb. 8, 2018, the entire contents of which are hereby incorporated by reference.

The invention relates to a flushing system for a catheter, in particular for a catheter of a catheter pump, comprising a supply line having a pump section, a discharge line having a pump section, and a pump. The invention also relates to an associated carrier element, an associated console and a catheter pump system.

A catheter pump is known from EP 2 288 392 B1, for example. The catheter pump has a drive unit and a catheter. The catheter comprises a pump head for insertion in particular into the arterial vascular system, such as the aorta or heart, and a rotatably mounted rotor shaft for driving an expandable conveying element provided on the pump head. A rotor that has fold-out propellers and is provided at the proximal end of the catheter can be used as the rotating conveying element.

Catheter pumps are inserted into the arterial vascular system, such as the aorta, of patients as a temporary circulatory support system, in particular when the natural heart is unable to provide the body with sufficient oxygenated blood. The conveying element and the rotor shaft are operated at comparatively high rotational speeds in the range of from 7,000 to 15,000 revolutions per minute, and in particular in the range of from 10,000 to 13,000 revolutions.

In order to prevent deposits forming in the catheter, to lubricate the catheter and in particular the rotor shaft rotating therein, and to prevent blood from entering the catheter, the catheter is flushed with flushing liquid. A flushing system is connected to the catheter for this purpose. A flushing system of this kind is already known from WO 2014/164136 A1, for example. In this case, a supply line for supplying flushing fluid and a discharge line for discharging flushing fluid are connected to the catheter. In order to achieve fluid conveyance in the supply line and discharge line, a rotary peristaltic pump is provided for the supply line and the discharge line in each case. The two pumps are actuated separately in this case in order to convey a corresponding amount of fluid into the catheter and conduct it out of the catheter, and to achieve a desired ratio of supplied to discharged fluid. This flushing system is both expensive and complex in design, because two pumps have to be provided, and complex to control or program, because the pumps have to be coordinated with one another.

The problem addressed by the present invention is therefore that of providing a flushing system for a catheter which remedies the above-mentioned disadvantages of the prior art.

This problem is solved by a flushing system having the features of claim1. The diameter of the pump section of the discharge line is thus smaller than the diameter of the pump section of the supply line. Furthermore, the pump cooperates with the pump section of the supply line in order to supply flushing fluid to the catheter. Finally, the pump cooperates with the pump section of the discharge line in order to discharge flushing fluid from the catheter.

Consequently, there is only one pump, which is designed both to supply fluid into the catheter through the supply line and to discharge fluid out of the catheter through the discharge line. The fact that the diameter of the pump section of the discharge line is reduced compared with the diameter of the supply line means that the ratio of supplied fluid to discharged fluid can be set and adjusted without a second pump being required. In this case, the pump section of the discharge line cooperates with the pump in such a way that a kind of throttle point for the flushing fluid is formed. It can thus be achieved that approximately ⅔ of the flushing fluid pumped into the catheter remains in the body in which the catheter is located, and approximately ⅓ of the flushing fluid flows back through the catheter, and is discharged from the catheter by means of the discharge line.

The catheter may be the catheter of a catheter pump, as stated above. It may also be one of a wide range of other catheters, such as a catheter of a stent delivery system.

According to an advantageous development of the invention, the pump is designed as a peristaltic pump. In particular, the pump may be designed as a linear peristaltic pump. It is conceivable for the pump to have a camshaft having a number of cams, each cam being coupled in motion to a finger. Each finger cooperates with the supply line and the discharge line in order to convey fluid. In particular, the fingers sequentially compress the supply line and the discharge line to generate a fluid flow. The movement of the fingers results in the squashed pump section region also migrating such that a fluid flow is achieved. Overall, therefore, fluid can be supplied to the catheter and fluid can be discharged from the catheter by means of only one pump.

It is also advantageous for the pump sections to extend in parallel with one another and for flushing fluid to flow therethrough in opposite flow directions during operation. A flushing system of this kind has a particularly simple and compact design.

It is particularly preferred for a carrier element to be provided to which the supply line and the discharge line are fastened. The carrier element makes it possible to provide, in a particularly simple manner, an operative connection between the supply line and discharge line and the pump by the carrier element being suitably mounted in the pump region such that the pump sections of the supply line and discharge line can cooperate with the pump.

It is further particularly preferred for the carrier element to extend along a main extension plane. In this connection, it is conceivable for the supply line and discharge line to extend through the carrier element in said main extension plane. The carrier element is therefore particularly compact and can be connected in a particularly simple manner to a linear peristaltic pump.

It is further particularly preferred for the carrier element to have an opening, the pump sections of the supply line and discharge line extending along the opening and thus bridging it. It is conceivable for the fingers of the linear peristaltic pump to engage in the opening and to thus cooperate with the pump sections which bridge the opening.

Advantageously, the supply line and/or the discharge line have an arcuate section, the section extending through the carrier element such that the supply line and/or discharge line are guided into the carrier element and out of the carrier element on the same side of the carrier element. The supply and/or discharge line can thus be supplied to the carrier element on one carrier-element side and guided out of the carrier element on the same side. This is advantageous in that the two lines can be supplied by means of only one pump, and in particular by means of a linear peristaltic pump, such that the fluid is conveyed in the supply line for supplying and is conveyed in the other line for discharging. It is also conceivable, however, for the supply and/or discharge line to be guided into or out of the carrier element on opposite sides.

It is further preferred for a console having the pump to be provided. In this case, the pump sections of the supply line and discharge line can be inserted into a receptacle in the console in such a way that the pump can cooperate with the pump sections in order to convey fluid. Thus, by inserting the pump sections into the console, an operative connection between the pump and the supply line and discharge line can be provided in order to convey fluid into and out of a catheter.

It is particularly preferred for the carrier element together with the supply line and discharge line to be detachably placeable on the console. In contrast with the console, the supply line and discharge line are wear items, since these usually have to be sterile. A new supply line and discharge line have to be used for each patient. In this respect, the supply line and discharge line can be replaced quickly by simply removing or rearranging the carrier element together with the supply line and discharge line on the console.

Advantageously, the console has a closing element for closing the receptacle, the pump sections cooperating with the pump in order to convey fluid only when the closing element assumes its closed position. In this context, it is conceivable for the closing element to have an operative section which is provided opposite the fingers of the linear peristaltic pump such that the pump sections are provided between the operative section and the fingers.

In this connection, a particularly preferred development of the invention results from the fact that the closing element has a pressing element which presses the supply line and/or the discharge line against the fingers under preloading. In this case, one or more spring elements can be provided in order to push the pressing element against the supply and/or discharge line. It is in particular conceivable for the pressing elements to be arranged opposite the fingers of a linear peristaltic pump such that the pressing elements exert a continuous force on the pump sections in the direction of the fingers, while the fingers sequentially apply a force to the pump sections in the direction of the pressing elements in order to generate a fluid flow.

The problem stated at the outset is also solved by a carrier element for a flushing system according to the invention, the supply line and the discharge line being fastened to the carrier element. This wear item can be fastened particularly easily and replaceably in particular to the console.

Furthermore, the problem stated at the outset is also solved by a console for a flushing system according to the invention, the console having a pump and a receptacle for the pump sections. The pump sections of the supply line and discharge line can be inserted into the receptacle in such a way that, after insertion, there is an operative connection between the pump and the pump sections in order to generate a fluid flow through the lines.

Finally, the problem stated at the outset is also solved by a catheter pump system. The catheter pump system in this case comprises a catheter pump having a catheter and a flushing system according to the invention, the supply line and the discharge line of the flushing system being fluidically connected to the catheter. The catheter of the catheter pump can be flushed in a particularly simple manner by means of the flushing system.

FIGS.1and2show a catheter pump10comprising a drive unit12and a catheter18that can be coupled to the drive unit12. The catheter18has, at its distal end, a pump head15for insertion into the arterial vascular system, such as the aorta. The catheter18is designed to be inserted into the body of a mammal, such as a human, via the femoral artery and to be positioned for example in the aorta in order to support the circulation of the heart. The catheter18is relatively long, such that it can extend from the percutaneous insertion site in the femoral artery, for example, into the groin and up to the aortic arch.

A rotor shaft32is provided in the catheter18, by means of which shaft a conveying element provided in the pump head15, such as a rotor having fold-out propellers, can be rotated. The drive unit12has a receptacle14. The proximal end16of the catheter18is arranged in the receptacle14and is securely held there by means of a holding element20. At its proximal end16, the catheter18provides a coupling section30which can be placed into the drive unit12, by means of which ultimately the rotor shaft32, and thus the conveying element, is rotated.

Furthermore, two tubes22,24are provided at the distal end16. Flushing fluid can be introduced into the catheter18by means of the tube22via an inlet26. Said flushing fluid is conducted through the catheter18to the pump head15. In the pump head15, some of this flushing fluid is guided back through the catheter18and discharged via an outlet28and the tube24. In this process, the recirculated flushing fluid is guided back between the rotor shaft32that rotates during operation and an inner catheter33. The inner catheter33is surrounded by an outer catheter35, with flushing fluid being conveyed via the lumen between the inner catheter33and the outer catheter35toward the pump head15.

The tubes22,24each have a connector piece36,38. Said connector pieces36,38can be connected to a flushing system, which will be described in more detail below. The flushing system is shown inFIGS.3and4and denoted as a whole by reference numeral40. First, the flushing system40comprises a console42. Said console comprises two hooks44,46on its rear side, by means of which the console can be fastened to a hospital bed, for example. The console42further comprises a holding section48so that the console42can be conveniently carried by an operator. The console further comprises a receptacle50, which can be seen inFIG.4, which can be closed by a pivotable closing element51.

Furthermore, the console42comprises a pump52designed as a linear peristaltic pump. This pump52will be described in more detail below with reference toFIGS.4and7: First, the pump52comprises a camshaft56having a number of cams (not shown). The cams are each coupled in motion to a finger54. Said fingers54move in the radial direction, i.e. perpendicularly to the axis of rotation of the camshaft56. The fingers54move in this case sequentially, i.e., collectively, the fingers54move together in a wave-like manner.FIG.4shows the fingers, which protrude into the receptacle50and are covered by a cover58. A carrier element60can be arranged in the receptacle50and has a supply line62and a discharge line64.

The carrier element60and the lines62,64are described in more detail below with reference toFIGS.3to6. First, the supply line62comprises a connector piece66, while the discharge line64comprises a connector piece68. The connector piece66can in this case be connected to the connector piece36of the tube22of the catheter pump10(cf.FIG.2). The connector pieces66and36may form a Luer connection. Likewise, the connector piece68of the discharge line64can be connected to the connector piece38of the tube24of the catheter pump10. The connector pieces38and68may also form a Luer connection.

As can be seen clearly inFIGS.5and6, the carrier element60extends in a main extension plane and has a modular design. The carrier element60is made of PET and is produced by plastic deep drawing or injection molding. The supply line62and the discharge line64are fastened to the carrier element60or extend through the carrier element60. The carrier element60has channels for this purpose, in which the lines62,64are guided. In the central region, the carrier element60has a rectangular opening70. The lines62,64extend along this opening70and bridge it.

The supply line62comprises a pump section72in the region of the opening70. At the same time, the discharge line64comprises a pump section74. The pump section72has a diameter d1, while the pump section74has a diameter d2. The diameter d1is greater than the diameter d2. The function of this diameter difference will be described in more detail below.

Two membranes76,78, which may consist in particular of silicone, are provided on the carrier element60. By means of these membranes76,78, a pressure measurement can be carried out in the supply line62and the discharge line64, as will be described in more detail below. Furthermore, the carrier element60has a further opening80. This opening80is bridged only by the supply line62. As can be seen inFIGS.3and4, the supply line62has a further connector piece82. By means of this connector piece82, the supply tube62can be connected to a bag84. The bag84contains flushing fluid. The bag84is fastened to a fastening hook85of the console42. The supply line62further comprises a container86with an enlarged diameter. Said container86is located between the connector piece82and the carrier element60. The container86can be fastened to a receptacle88on the console and abuts a console-side window90. By means of this arrangement, a fill-level measurement of the supply line62can be provided for example by means of a capacitive sensor. The discharge line64also has a connector piece92. The connector piece92can in this case be connected to a collection bag94for used flushing fluid. The collection bag94is also fastened to a fastening hook95of the console42. The fastening hooks85,95together with the bags84,94are provided on opposite short sides of the console42.

The console has a number of fixing bolts96for fastening the carrier element60in the receptacle50. Once the carrier element60is arranged in the receptacle50, the receptacle50can be closed, as shown inFIG.3. For this purpose, the closing element51is transferred from the open position shown inFIG.4into its closed position shown inFIG.3. In order to close the closing element51, said element has a closing flap98. The closing flap98can be seen particularly clearly inFIG.8. This is pivotable. In order to close the closing element51, the closing flap98is pivoted such that teeth100of the closing flap98engage behind a console-side fastening strip102such that the closing element51is securely closed in the closed position.

As can be seen fromFIG.3, the supply line62is guided into the console42on one side and guided out thereof on an opposite side. In contrast, the discharge line64is guided into and out of the console42on the same side, in particular on the side on which the discharge line64is guided out of the console42in the direction of the catheter pump10. Accordingly, the discharge line64is guided in an arc (visible inFIG.6) through the carrier element60such that the discharge line64has an arcuate section69.

In order to push the supply line62and the discharge line64against the fingers54of the pump52in the closed position of the closing element51, the closing element51has a pressing element104,106for the supply line62and the discharge line64in each case. Said pressing elements104,106can be clearly seen inFIG.7. Said elements extend in each case along the pump sections72,74and are pushed at the lateral ends by at least one spring element108,110in each case against the fingers54. As can be seen inFIG.4, a cover112is arranged over the pressing elements104,106.

The closing element51also has a pushing element114,116in each case, which can likewise be seen inFIG.7, a compression spring118,120also being provided here in each case. The pushing elements114,116cooperate in this case with the membranes66,68and console-side sensor elements122,124(cf.FIG.4) such that a pressure measurement is possible in the supply line62and in the discharge line64. A console-side sensor element126and a closing-element-side strip128, which act on the supply line62such that air bubble detection can be carried out, engage in the recess80in the carrier element60in the closed position. Indeed, as far as possible no air bubbles or other gas bubbles should be allowed through the supply line62. Air bubble detection can in this case be carried out by means of optical methods or by means of capacitive measurement, for example.

The operation of the flushing system40is then as follows: First, the flushing system40is connected to the catheter pump10to form a catheter pump system. The connector66of the supply line62is connected to the connector36of the catheter pump in the process. Similarly, the connector68of the discharge line64is connected to the connector38of the catheter pump10. The pump52can then be started. Thereafter, flushing fluid is supplied to the catheter18of the catheter pump10from the bag84via the supply line62and the tube22. The flushing fluid can in this case consist of a 20% sterile glucose solution. Heparin may be added to the flushing fluid. The amount of flushing fluid can be set to 600-2,500 ml/24 h in operation, and approximately 12,000 ml/24 h when there is filling with a significantly larger flow.

Flushing fluid then flows through the catheter10in the distal direction. Some of the flushing fluid is then guided back through the catheter18in the proximal direction and acts as a lubricant for the rotor shaft32of the catheter18. Furthermore, blood is effectively prevented from entering the catheter18by the flushing fluid. The used flushing fluid is then supplied to the collection bag94via the tube24and the return line64. On account of the fact that the diameter d2of the pump section74of the return line64is smaller than the diameter d1of the pump section72of the supply line62, the pump section64cooperates with the pump52as a throttle point. Thus, approximately one third of the flushing fluid pumped into the catheter18is pumped out of the catheter again, while two thirds of the flushing fluid enters the patient's circulation, with blood being prevented from entering the catheter18at the same time. Accordingly, the cross-sectional area of the diameter d2of the pump section74of the return line64is also approximately only one third of the cross-sectional area with the diameter d1of the pump section72of the supply line62.

Each finger54of the pump52acts on the two pump sections72and74in the same way. The linear peristaltic pump52is a positive displacement pump in which the flushing fluid to be conveyed is forced through by external mechanical deformation of the lines62,64or pump sections72,74thereof, the compressed section of the pump sections72,74“migrating” due to the sequential axial movement of the fingers54. A pressure measurement is possible in the lines62,64by means of the sensor elements122,124, while air bubble detection is possible in the supply line62by means of the sensor element126.

The main functions of the console42are to monitor and control the rotational speed of the catheter pump10and the flow rate of the flushing fluid. The console42has two monitors on a broad face. The first monitor130serves as a main monitor and is designed as a touch screen. All control and monitoring parameters for the system are displayed on the monitor130. An operating system, such as Windows, serves as an input system on the screen in this case. A separate operating system, which is specially designed for medical electronics, is used to control the catheter pump10and/or the flushing system40. The control of the medical electronics is used in particular to control the rotational speed of the catheter pump10and the pump52of the flushing system40. Should the monitor130fail for any reason, the console42has a second emergency monitor132. This monitor has only a few functions, such as indicating the rotational speed of the catheter pump10. By means of this so-called SUI (Safety User Interface), the operation of the catheter pump10and/or the flushing system40can only be terminated, but not started.