SYSTEM AND METHOD FOR PREPARING A CATHETER BEFORE USE

Abstract

A system and method are disclosed in the field of preparing a catheter for use in a patient, in particular a catheter of an intravascular blood pump, more specifically for properly purging and de-airing the catheter. The catheter comprises an elongate tubular portion and a connected device. The elongate tubular portion is configured to be inserted into a patient's blood vessel and defines a lumen. The connected device is connected to the elongate tubular portion and has a cavity, which may accommodate a drive unit of the blood pump, and which is in fluid communication with the lumen of the elongate tubular portion. In order to securely de-air the system, a sensor, such as an accelerometer, for detecting an orientation of the connected device is provided, and a user may be guided to correct the orientation of the connected device for proper purging.

Claims

1. A system comprising a catheter, the catheter comprising an elongate tubular portion and at least one connected device, the elongate tubular portion configured to be inserted into a patient's blood vessel and having a proximal end and a distal end and a lumen extending from the proximal end to the distal end, each connected device connected to the elongate tubular portion and having at least one cavity, wherein the at least one cavity is in fluid communication with the lumen of the elongate tubular portion, wherein the system further comprises at least one sensor for detecting an orientation of at least one of the elongate tubular portion and the at least one connected device.

2. The system of claim 1, further comprising a control unit configured to receive data from the at least one sensor including the orientation detected by the at least one sensor and to determine whether the detected orientation matches an orientation in which air is releasable from the cavity.

3. The system of claim 1, wherein a difference of the detected orientation and a predetermined orientation is computable to guide a user to change the orientation in order to approach the predetermined orientation.

4. The system of claim 1, wherein the control unit is configured to display at least one of: a matching indicator representing the matching of a detected orientation with an orientation in which air is releasable from the cavity, the detected orientation, and a representation indicating the difference between the detected orientation and the predetermined orientation.

5. The system of claim 3, wherein the predetermined orientation is a vertical orientation or a conical range around a vertical axis defined by a predetermined angle.

6. The system of claim 1, wherein the at least one sensor is arranged in the connected device and configured to detect an orientation of the connected device.

7. The system of claim 1, wherein the at least one sensor (15) includes at least one of a gravity sensor, an accelerometer and a gyroscope.

8. The system of claim 1, further comprising a pump unit, and a drive unit to provide an intravascular blood pump for percutaneous insertion into a patient's blood vessel, wherein the pump unit is one of the at least one connected device and is disposed at the distal end of the elongate tubular portion of the catheter and comprises a cavity, the pump unit including an impeller which is rotatable about an axis of rotation to convey blood from a blood flow inlet to a blood flow outlet of the pump unit, wherein the pump unit is preferably an expandable pump unit with the impeller being coupled to a flexible drive shaft which extends through the lumen of the elongate tubular portion of the catheter, and wherein the drive unit is disposed in the at least one cavity of a handle portion which is another one of the at least one connected device and which is coupled to the flexible drive shaft so as to cause rotation of the impeller.

9. A method of preparing a catheter for use in a patient, the catheter comprising an elongate tubular portion and a at least one connected device, the elongate tubular portion being configured to be inserted into a patient's blood vessel and having a proximal end and a distal end and a lumen extending from the proximal end to the distal end, each of the at least one connected device connected to the elongate tubular portion and having at least one cavity, wherein the at least one cavity is in fluid communication with the lumen of the elongate tubular portion, the method comprising the steps of: supplying a fluid into at least one of the at least one cavity of at least one of the at least one connected device and the lumen of the elongate tubular portion to purge at least one of the at least one cavity and the lumen; detecting an orientation of at least one of the elongate tubular portion and the at least one connected device.

10. The method of claim 9, further comprising determining whether the detected orientation matches an orientation in which air is releasable from the cavity.

11. The method of claim 9 or 10, in which a difference between the detected orientation and a predetermined orientation is computed to guide a user to change the orientation in order to approach the predetermined orientation.

12. The method of claim 9, further comprising displaying at least one of: a matching indicator representing the matching of a detected orientation with an orientation in which air is releasable from the cavity, the detected orientation, and a representation indicating a difference between the detected orientation and the predetermined orientation.

13. The method of claim 11, wherein the predetermined orientation is a vertical orientation or a conical range around a vertical axis defined by a predetermined angle.

14. The method of claim 11, wherein the fluid supply is activated, when the detected orientation matches the predetermined orientation, and the fluid supply is deactivated, when the detected orientation differs from the predetermined orientation.

15. The method of claim 9, further comprising measuring a volume of the supplied fluid.

16. The method of claim 9, wherein the orientation is detected by means of at least one sensor, wherein the at least one sensor includes at least one of a gravity sensor, an accelerometer and a gyroscope, wherein the at least one sensor is preferably arranged in at least one of a handle portion and a pump unit and the elongate tubular portion, wherein the handle portion is one of the at least one connected device and the pump unit is another one of the at least one connected device, wherein the sensor preferably includes a camera that is preferably arranged outside of the handle portion and the pump unit and the elongate tubular portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The foregoing summary, as well as the following detailed description of preferred embodiments, will be better understood if read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, reference is made to the drawings, which are to be understood as schematic and may not be true to scale. The drawings are exemplary for illustrating the present invention, and the scope of the disclosure is not limited to the specific embodiments disclosed in the drawings. In the drawings:

[0027] FIG. 1 shows a system in accordance with an embodiment of the present invention, including an intravascular blood pump connected to a control unit.

[0028] FIG. 2 shows the blood pump of FIG. 1 in more detail.

[0029] FIG. 3a to FIG. 3c schematically illustrate a handle portion or a pump unit of a catheter at different orientations during the purging process.

DETAILED DESCRIPTION

[0030] FIG. 1 shows a system 100 in accordance with an embodiment of the present invention. In particular, the system 100 comprises an intravascular blood pump 10 connected to a control unit 5. The intravascular blood pump 10 comprises a catheter 1 with a pump unit 2 connected to the distal end 22 of the catheter 1, more specifically to an elongate tubular portion 11 of the catheter 1 (see FIG. 2). The pump unit 2 is also called a connected device 230. A handle portion 3 is connected to a proximal end 21 of the elongate tubular portion 11. The handle portion 11 is also called a connected device 230. The handle portion 3 can be grabbed by a user for handling the catheter 1 and will not be inserted into the patient. The intravascular blood pump 10 may be designed to act as a left ventricular assist device and may be inserted into a patient's aorta toward the heart, more specifically the left ventricle of the patient's heart. In this case, the pump unit 2 will be placed through the aortic valve to convey blood from the left ventricle into the aorta. However, it will be appreciated that the blood pump 10 may be designed for a different application, such as to act as a right ventricular assist device, or the catheter may be designed for a different field than intravascular blood pumps.

[0031] Still referring to FIG. 1, the handle portion 3 accommodates a drive unit 4 of the blood pump 10, which will be explained in more detail below. In order to control the drive unit 4, an electric connecting cable 7 is provided connecting the intravascular blood pump 10 to the control unit 5. The control unit 5 has a user interface comprising a display 6. It will be appreciated that the control unit 5 may comprise various further control elements, such as a touch screen, control dials, buttons or the like. The display 6 may be configured to display various operation parameters of the blood pump 10, such as pump flow rate, pump speed, motor current, etc. In particular, in view of the present invention, the display 6 may display during an initial purging process a representation of the orientation of a connected device 230, for example the handle portion 3, which is detected by a sensor 15. As indicated in FIG. 1, the current orientation 27 of the connected device 230 may be displayed relative to a predetermined target orientation 28 of the connected device (indicated in dashed lines in FIG. 1). Any other display options suitable to guide a user may be implemented. Further, or in an alternative example, the orientation 27 of the pump unit 2 may be displayed.

[0032] Besides the electrical connection, the blood pump 10 is further connected to a purge line 8 which is provided for supplying a purge fluid to the blood pump 10 for an initial purging and de-airing process as well as during operation of the blood pump 10. The purge line 8 may be connected to a purge cassette 9, which may be provided for generating a certain purge pressure, which may be for instance 500 mmHg. A purge fluid, which may be any suitable fluid, such as water, or preferably a dextrose solution, may be provided in a container or bag 17 and supplied to the purge cassette 9 and further, via the purge line 8, to the blood pump 10. Details of the method of preparing the blood pump 10 will be described in more detail below with respect to FIG. 3a to FIG. 3c.

[0033] Referring now to FIG. 2, the intravascular blood pump 10 of the system 100 of FIG. 1 is described in more detail. The blood pump 10 comprises two connected devices 230 which are the handle portion 3 and the pump unit 2. Each of the connected devices 230 comprises a cavity 13. Each of these cavities 13 is in fluid communication with a lumen 12 of the elongate tubular body 11. The blood pump 10 of the embodiment shown is an expandable catheter pump, in other words, the pump unit 2 is expandable from a compressed configuration (not shown) to an expanded configuration. More specifically, in order to insert the blood pump 10 through a small access into a patient's blood vessel, the pump unit 2 will be compressed to the compressed configuration to reduce its diameter. Once placed at a target location, for instance the left ventricle and the aorta, the pump unit 2 may expand. For this purpose, the pump unit 2 may comprise an expandable pump casing 23, which may be in the form of a cannula and may be formed of a mesh-like support structure covered by a thin polymer membrane. The support structure may be made of a shape memory material, such as nitinol. The pump unit 2 may have at its distal end an atraumatic tip 24, also known as J-tip or pig tail. An impeller 18, which may be expandable and compressible, respectively, as well, is disposed inside the pump casing 23. In particular in the aforementioned application for left ventricular support, a blood flow inlet 19 may be formed in a distal portion of the pump casing 23, for instance in an enlarged diameter portion. Blood enters the pump casing 23 and is conveyed by means of an impeller 18 rotating about an axis of rotation through the pump casing 23, and out of a blood flow outlet 20 (indicated by arrows B).

[0034] The impeller 18 is coupled to a flexible drive shaft 16, which extends through the catheter 1, more specifically through the lumen 12 of the elongate tubular body 11 of the catheter 1. The flexible drive shaft 16 is coupled to a drive unit 4 which is located inside the cavity 13 of the handle portion 3. The drive unit 4, which is only schematically illustrated in FIG. 2, may comprise an electric motor. Further electronic parts of the drive unit 4, such as a PCB 26, are connected to the cable 7, which in turn is connected to the control unit 5 as explained above with respect to FIG. 1.

[0035] A sensor 15 for detecting the orientation of the handle portion 3 is placed on the PCB 26 to be able to transmit data relating to the current orientation to the control unit 4. Before use in the patient, in particular the cavity 13 of the handle portion 3 and the lumen 12 of the elongated tubular portion 11 of the catheter 1, and also the pump unit 2, have to be completely de-aired, that means air bubbles have to be completely removed from all cavities of the blood pump 10 to prevent air from being introduced into the patient's vascularity, which may cause severe complications, such as an infarct. In order to supply a purge fluid to the blood pump 10, the purge line 8 is connected to a purge fluid inlet 25 of the handle portion 3. A person skilled in the art will understand that various connectors, such as Y-connectors, Luer-connectors or the like may be used to connect the various lines and cables. Further or in the alternative, a sensor may be placed in the pump unit, additionally or alone.

[0036] Referring now to FIG. 3a to FIG. 3c, a method of preparing a catheter in accordance with an embodiment of the present invention is described. In particular, as explained above, during the preparation of catheter 1 before it can be used in a patient, air bubbles shall be completely removed. While there is substantially no risk that air bubbles are trapped in the lumen 12 of the elongate tubular body 11 of the catheter 1, air bubbles might be trapped inside the cavity 13 of connected devices as the handle portion 3 and/or the pump unit 2. In particular, there is a risk that purge fluid exiting the catheter 1 at the distal end 22 (i.e. exiting the pump unit 2) may erroneously imply that the catheter 1 has been successfully de-aired. This is because the cavity 13 of the handle portion 3 (or the pump unit—not shown) may have recesses or other geometrical structures of the inner wall or of built-in components which may still be filled with air while the purge fluid already flows through the lumen 12 of the elongate tubular portion 11 of the catheter 1. In particular, the lumen 12 may have a very small diameter such that capillary forces may draw the purge fluid into the lumen 12 although there still is air in the cavity 13 of the handle portion 3 and/or the pump unit. Furthermore, the cavities or built-in components may have irregular structures that further increase the risk of entrapped air bubbles.

[0037] The risk of air bubbles being trapped inside the handle portion 3 and/or the pump unit 2 can be substantially reduced or eliminated if the handle portion 3 and/or the pump unit 2 is held in a correct orientation during the initial purge process for de-airing the catheter 1. Therefore, the system 100 of the present invention includes a sensor 15 for detecting the orientation of the handle portion 3 and/or the pump unit 2. In other words, the current orientation of the handle portion 3 and/or the pump unit 2 can be detected while supplying the purge fluid through the line 8 (see arrow P) into the handle portion 3 or into the pump unit via the tubular portion 11. In particular, the current orientation may be detected continuously or at certain time intervals, preferably very short time intervals, such that the orientation can be properly monitored.

[0038] The sensor 15 may be a gravity sensor, accelerometer, gyroscope or any other sensor, which is able to detect an orientation. In particular, it is sufficient to detect the orientation, and it may not be necessary to detect the absolute position of the handle portion 3 and/or the pump unit 2 in three-dimensional space, particularly in relation to gravity. Especially an accelerometer does not require any external infrastructure, like external field generators or the like, and is robust against a magnetic field, which may be caused by the drive unit 4. Thus, an accelerometer may provide an exact orientation.

[0039] In particular, the orientation may be represented by a tilt angle α enclosed by a general longitudinal axis L and/or the pump unit 2 and a vertical axis V, preferably along gravity. As indicated by the arrows in FIG. 3a to FIG. 3c, an accelerometer 15 typically detects a vertically downward direction. The sensor data can then be used to calculate the tilt angle α relative to the particular downward direction. The detected orientation may be transmitted to the control unit 5. Preferably, the sensor data obtained by the sensor 15 are transmitted using memory mapping, which eliminates the need for further connection wires, and the existing connecting cable 7 can also be used for transmitting the sensor data. The control unit 5 can display the detected orientation calculated from the sensor data on a display 6 as illustrated in FIG. 1. Further, the control unit 5 may be configured to guide the user to change the orientation of the handle portion 3 or the pump unit 2 toward a predetermined target orientation. As illustrated in FIG. 3a to FIG. 3c, the display 6 may also give a positive and negative indication 29 whether the current orientation matches the predetermined target orientation or not, respectively.

[0040] A de-airing process will be described with the handle in FIG. 3a-3c as an example that can also be applied to the pump unit 2 analogously: The predetermined target orientation may be chosen depending on the interior geometry of the handle portion 3, to be the orientation in which air bubbles can securely exit the cavity 13 of the handle portion 3 into the lumen 12 of the elongated tubular portion 11 of the catheter 1. The predetermined target orientation may be a vertical orientation as shown in FIG. 3a, in which further a purge fluid line 8 is located vertically below the proximal end 21 of the tubular portion 11, i.e. at an angle α of 0 degrees, or, in other words, in which the vertical axis V is coincident with the longitudinal axis L. In this orientation, the purge fluid 30 is introduced from below and can securely push any air 31 in a vertically upward direction such that the cavity 13 and that the lumen 12 can be securely de-aired. It will be appreciated that any angle α greater than 0 or any range of angles may be selected to define the predetermined target orientation.

[0041] As shown in FIG. 3b, if the handle portion 3 is held at an oblique angle, for instance an angle α greater than 0 degree and below 90 degrees, such as 45 degrees, air 31 may be trapped in a corner of the cavity 13 of the handle portion 3 while the purge fluid 30 already is present in lumen 12. Likewise, as shown in FIG. 3c, if the handle portion 3 is held in an orientation in which the fluid inlet into the handle portion 3 is located vertically above the exit into the lumen 12, i.e. for instance at an angle α greater than 90 degrees up to 180 degrees, air 31 may be trapped in a corner of the cavity 13 of the handle portion 3. Nevertheless, purge fluid may continuously exit the catheter 1 at the distal end 22, thereby making the user erroneously believe that he has successfully de-aired the catheter 1.

[0042] Therefore, the user is guided how to hold the handle portion 3, in other words how to change the orientation of the handle portion 3 such that it matches the predetermined target orientation. The detected orientation, that means the current orientation detected by the sensor 15 is compared to the predetermined target orientation and a suitable indication is displayed on the display 6, e.g. at least one of the indications 27, 28 and 29 as described above. It will be appreciated that any indication representing the difference between the current detected orientation and the predetermined target orientation suitable to guide a user to choose the correct orientation may be envisioned, such as graphic illustrations, color scales, arrows or the like. Likewise, in addition or alternatively, an acoustic signal may be used to guide the user to change the correct orientation to approach and match the predetermined target orientation, which is necessary for completely de-airing the system.

[0043] While the purge fluid may be continuously supplied by the fluid line 8 to the cavity 13 and to the lumen 12 during the aforementioned purging and de-airing process, it may be advantageous to activate the flow of purge fluid only if the user holds the handle portion 3 in the correct orientation. Vice versa, the flow of purge fluid may be stopped or paused if the user does not correctly hold the handle portion 3. This may reduce or eliminate the risk that the purge fluid is drawn into the lumen 12 too early although air is still present in the handle portion 3. The volume of supplied purge fluid may be measured such that based on the known volume of all cavities in the catheter 1, an indication may be displayed once the purging and de-airing process is completed. For safety reasons, the control unit 5 may prompt the user to confirm that the purge fluid exits the blood pump 10 at the distal end, and a safety margin for the amount of purge fluid may be added.

[0044] The disclosed method and system allow for proper and secure preparation of a catheter for use in a patient, in particular proper purging and de-airing the catheter in order to prevent air bubbles from being introduced into the patient's vascularity. It will be appreciated that the invention is particularly useful in the field of intravascular blood pumps but may be implemented in any catheter which requires proper de-airing before used in a patient.