Patent Application
20180168683
The present invention relates to cannulation. In particular, the present invention relates to a cannula, an instrument and a method for inserting a catheter.
Cannulation, i.e. the insertion of a catheter, of a hollow needle or of a cannula in a tissue, is used in medical treatments and surgeries, such as in ophthalmic surgeries. Cannulation can also be used in other non-medical applications where the insertion may not be performed on a tissue but on another ground.
A sub-discipline of ophthalmic surgeries are vitreo-retinal surgeries, where retinal vessels and sub-retinal layers may be cannulated, e.g. for the treatment of vein occlusion diseases, such as a diabetic retinal vein occlusion and for the treatment of Aged-related Macular Degeneration (AMD). For the treatment by use of instrumental micro cannulation liquids may be injected into a tissue and/or extracted from a tissue.
EP 1 738 790 A1 provides an example for a device for the injection of drugs into a retinal micro vessel by using a catheter. The catheter is carried by a sleeve which can be mounted to an endoscope which is used in vitreo-retinal surgery. The catheter has a sharp tip which can be introduced into a retinal vessel under visualization and control with the endoscope.
Another example for an instrument which is suitable for microsurgical injection is provided in US 2003/0171722 A1. The instrument comprises a hollow miniaturized needle for penetrating a retinal vessel. The needle may carry a flexible tube which is movable through the needle. The needle may be illuminated by use of an optical fiber.
The object of the present invention is to provide a cannula, an instrument and a method which allow for an improved cannulation, in particular for a precise and safe cannulation.
This object is solved by the independent claims. Preferred embodiments are defined in the dependent claims.
The present invention relates to a cannula for inserting a catheter, wherein the cannula comprises a first channel for receiving and guiding the catheter. The first channel extends to a first opening and has an end portion defining an insertion direction, such that the catheter when being advanced and guided through the end portion of the first channel exits the cannula through the first opening in the insertion direction. The cannula further comprises a second channel for receiving a pointing device for providing a pointing beam. The second channel extends to a second opening and has an end portion defining a pointing direction. The pointing direction points from the second opening towards a location, which is located outside the cannula along the insertion direction in front of the first opening.
The cannula can be used in combination with a suitable pointing device and a suitable catheter. A suitable pointing device can be received in the second channel and can provide a pointing beam in the pointing direction when received in the second channel. A suitable catheter can be advanced through the cannula to exit the first opening in the insertion direction. The cannula is formed, such that the pointing direction points from the second opening towards a location, which is located outside the cannula along the insertion direction in front of the first opening. Accordingly, there is a location which is defined by the cannula and which corresponds to an intersection of the pointing direction and the insertion direction. The pointing beam of a pointing device along the pointing direction can be used to indicate or mark the location of the intersection with respect to a target location on a ground, e.g. a tissue or a vessel. Because the location of the intersection can be marked, it is possible to adjust the position and the orientation of the cannula, such that the intersection coincides precisely with the target location. In this position and orientation of the cannula—where the intersection and the target location coincide—the insertion direction of the cannula intersects the target location, such that the catheter can be advanced through the cannula to penetrate the ground at the target location. Therein, the insertion can be performed just by advancing the catheter through the cannula without need to move the cannula relative to the ground. Further, during the insertion or penetration the position and orientation of the cannula can be fixed and stabilized while the pointing beam may still be used to verify the correctness of the position and orientation of the cannula. In other words, since the cannula allows for separating the step of positioning from the step of inserting, it can be ensured that a penetration of the ground only takes place when the cannula is correctly positioned and orientated and may be stabilized in its position. The insertion itself can be performed just by advancing or moving the catheter trough the cannula. Hence, the cannula allows for an easy and precise adjustment by monitoring and controlling the position and orientation of the cannula and for a precise and safe insertion of a catheter at a target location.
In the cannula, the second channel may extend parallel to the first channel and/or the first channel may protrude a leading end of the second channel. If the channels are parallel, the cannula can have a smaller diameter which is advantageous when using the cannula for surgeries where the cannula may be introduced in a tissue. If the first channel protrudes a leading end of the second channel, the pointing beam may propagate from the second opening in a direction which is adjacent and parallel to a protruding portion of the first channel. Accordingly, the space which is required for the cannula, for the pointing device and for the propagation of the beam may have a longitudinal shape with a small diameter which is advantageous for applications with corresponding spacial requirements, such as ophthalmic surgeries.
The cannula may have an end portion located at the first opening which is bent. Accordingly, the insertion direction can be defined by a bent end portion of the first channel extending in the bent end portion of the cannula. Therefore, the intersection of the pointing direction and the insertion direction may be provided only by the path of the channel end portions while the first and second channels may extend essentially parallel outside the end portions. This allows for a thin longitudinal device and for keeping the lateral extension of the cannula small.
Preferably, the first channel and the second channel are formed in the same single part of material. This allows for a compact arrangement without having a connection between different parts in which the individual channels would be formed, respectively. This allows for a cannula having a high stability and for a cannula with a smooth and even outer surface without interruptions or irregularities.
The cannula may be a blunt cannula. Since the insertion or penetration does not need to be performed with the cannula but can be performed with a catheter, the cannula does not need to be pointed or sharpened. In medical applications a blunt cannula may reduce the risk of creating unwanted violations or penetrations in the tissue, compared to a cannula having a pointed tip.
According to one or more preferred embodiments, the cannula further comprises a support element being attached to an end portion of the cannula for stabilizing the cannula when the cannula is forced, e.g. along its length direction, against a ground, wherein the supporting element preferably comprises a material which is softer than the material in which the first and second channels are defined.
The support element may allow stabilizing the position and orientation of the cannula after the cannula has been positioned and orientated for the insertion of a catheter and when the cannula touches a ground with the support element close to the target location. The support element may also allow for pinching off a vessel thereby leading to a swelling of the vessel which alleviates the vessel cannulation by the catheter. Preferably, the support element is arranged at the position of the cannula, in which it touches the ground and supports and/or stabilizes the cannula, when the cannula is correctly positioned and orientated, i.e. when the intersection of the pointing direction and the insertion direction coincides with the target location, and when the cannula is pressed or forced against the ground. With respect to the surface of the ground, the correct position and orientation of the cannula may be an upright or angled position or orientation, for example.
If the support element comprises a soft material, the friction between the cannula and the ground, e.g. a tissue can be increased and a slippage of the cannula during the insertion can be avoided. Further, by using a soft material the risk of violating a tissue can be reduced.
According to one or more embodiments of the cannula, the first channel may comprise a portion having a first diameter which is larger than a second diameter of the end portion of the first channel, wherein the first diameter is preferably between 70 μm and 200 μm, in particular about 100 μm, and/or wherein the second diameter is preferably between 30 μm and 80 μm, in particular about 50 μm.
The portion of the first channel having a larger diameter can be used to receive a catheter portion having a correspondingly large diameter which may serve as a fluid tank or fluid reservoir. This is useful when using the cannula to inject a fluid into a tissue and/or to remove a fluid from a tissue. The thinner portion of the first channel allows receiving and guiding a portion of a catheter which may be correspondingly thin. This may be advantageous for micro cannulation when small tissue structures, such as micro vessels, are penetrated.
In a preferred embodiment, which can be used for ophthalmic surgeries, the cannula has a length of between 30 mm and 60 mm, preferably of about 40 mm, and/or a rear portion having a diameter of between 400 μm and 700 μm, preferably of about 560 μm, and/or a middle portion having a diameter of between 100 μm and 400 μm, preferably of about 200 μm, and/or an end portion having a diameter of between 60 μm and 150 μm, preferably of about 80 μm. For other applications, which also include non-medical applications, the cannula can have different dimensions.
The present invention further relates to an instrument comprising a cannula according to one or more of the above-mentioned embodiments and a pointing device which is received in the second channel of the cannula.
The present invention further relates to an instrument for inserting a catheter, which—different from the aforementioned embodiments—comprises a cannula which may not have a second channel for receiving a pointing device. This instrument comprises a cannula having a channel corresponding to the first channel which has been described above and which defines an insertion direction. The instrument further comprises a pointing device for providing a pointing beam in a pointing direction, wherein the pointing device is attached to the cannula and relatively arranged to the cannula, such that—when a pointing beam is provided—the pointing beam points and propagates towards a location, which is located outside the cannula along the insertion direction in front of an opening corresponding to the first opening which has been described above. Hence, in this embodiment, the pointing direction is not defined by a second channel but is defined by a pointing device being attached to the cannula. It is not necessary that the pointing device is in direct contact with the cannula. However, the pointing device is arranged with respect to the cannula, such that it is configured to define a pointing direction with respect to the position and orientation of the cannula. For example, the pointing device and the cannula may be rigidly connected, such that the movement of the cannula causes a corresponding simultaneous movement of the pointing device.
The pointing device of some or all of the aforementioned embodiments may comprise an optical fiber and/or a lens. The optical fiber can be received in the second channel, for example, or may be attached to the cannula. In some examples, the fiber can be part of or may correspond to an Optical Coherence Tomography (OCT) probe.
The lens can be arranged at the second opening or at another position at an end of the optical fiber, for example. The lens allows for providing a collimated or focused beam, which—different from a divergent illumination—is suitable for optically marking a target location on a ground by an optical spot or light spot. The spot may be magnified by using corresponding optics and may be directly visible, if light in the visible range is used, or may be visualized, if wavelengths are used, which are not directly visible.
The pointing device may further comprise a light source, such as a laser, a laser diode or an LED.
In one or more of the aforementioned embodiments, the instrument may further comprise a handle portion, wherein the handle portion preferably comprises a mechanism for moving a catheter and/or a mechanism for fluid injection and/or fluid removal. The mechanism for moving a catheter may, for example, comprise a piezo motor. The mechanism for fluid injection and/or fluid removal may comprise, for example, a piston which can be pushed into the catheter or drawn back within the catheter. The movement of the piston may be performed manually and/or electronically by a corresponding device, such as a robot.
Further, the handle portion and the cannula may be detachably connectable. This allows using a disposable cannula which may only be used for a single application, e.g. a surgery, while the handle portion may be used for a number of applications. This is particularly useful for applications which may require an uncontaminated and sterilized cannula or for applications where it is likely that the cannula is damaged or destructed.
The present invention further relates to an instrument comprising a cannula according to one or more of the before mentioned embodiments and further comprising a corresponding catheter which can be received and guided within the cannula.
The catheter preferably has a leading end which is pointed. This allows for a better penetration of a ground, such as the penetration of a micro vessel. According to a preferred embodiment, the catheter may comprise a catheter tube and a preferably flexible mandril which can be received and guided in the catheter tube and which can have a leading end which is pointed.
Further, the catheter may have a portion with a larger diameter compared to a leading portion of the catheter. The larger portion can be used as a fluid tank or fluid reservoir for fluids to be injected into a tissue and/or removed from a tissue.
Further, the provision of a portion with a larger diameter and a portion with a smaller diameter may lead to a shoulder portion or taper portion of the catheter where the diameter reduces abruptly or over a certain length to a smaller diameter. This portion may serve as a stopper, such that the catheter may only be advanced to a specific and defined end position where the stopper abuts against a portion of the cannula and avoids a further advancing. The position of the stopper along the catheter and the length and shape of the corresponding channel in the cannula may define a maximum length by which the catheter can be pushed or moved out of the cannula.
A possible application of the instrument of one or more of the aforementioned embodiments is the ophthalmic surgery, such that the instrument may be configured to provide the pointing beam inside an eye ball, preferably inside a human eye ball.
However, the present invention also comprises embodiments which may not be suitable for ophthalmic surgery. This might be due to unsuitable dimensions or proportions of the cannula, e.g. when the origin of the pointing beam is too remote from the opening where the catheter exits the cannula, or might be due to an unsuitable wavelength or intensity of the pointing beam. In other applications such dimensions, proportions or wavelengths can be suitable.
The present invention further relates to a method for inserting a catheter, preferably into a blood vessel, wherein the method comprises
The method and devices according to the present invention may also be used for refractive procedures such as catheter-based injection to the cornea. An example of this application is Deep Anterior Lamellar Keratoplasty (DALK); with the presented method and devices the surgeon can precisely guide the catheter into the posterior stroma, this method significantly reduces the decement membrane perforation rate.
Further advantages and details of the present invention will be understood from the following description in which preferred embodiments are described with reference to drawings. In the drawings same reference numerals designate corresponding features.
a), b) illustrate a portion of the cannula of
In the following description the present invention will be described in respect to a medical application in which the ground in which a catheter may be inserted corresponds to a tissue. However, this is only a specific example of an application. The present invention is not restricted to medical applications but also relates to other applications.
As is illustrated in
In
The second channel 32 is configured to receive a pointing device (not shown) which may comprise for example an optical fiber and a lens for collimating or for focusing an optical intensity to provide an optical beam which is suitable for pointing purposes. The lens may be arranged directly at the second opening 24 of the second channel 32. The lens may be an individual element which is separated from the optical fiber or can be a portion of the optical fiber itself, for example, when being formed of a portion of the optical fiber, e.g. by a melting technique.
The present invention includes also other embodiments of instruments, which are not illustrated, and which do not require a second channel for defining the pointing direction P. In these embodiments, the pointing direction P is defined by the position and orientation of the pointing device relative to the cannula 12.
In the embodiment of
For the cannula 12 of the illustrated embodiment the first and second channels 30, 32 extend essentially in parallel except for the portion of the first channel in the bent end portion 20. Accordingly, the cannula 12, the beam 48 and the intersection of directions I and P can be comprised in a thin longitudinal volume, as illustrated by
The insertion of a catheter 26 with the cannula 12 can be performed in two separate and sequential steps:
In a first step the cannula 12 is adjusted. In this step the cannula 12 is moved with respect to the retina 42 while simultaneously the spot which is created by the pointing beam 48 on the retina 42 or on the vessel 44 is observed. The cannula 12 can be moved manually by the surgeon or by a device, e.g. by a robot. The movement of the spot indicates a corresponding movement of the cannula 12 and the location of the spot indicates the position of the cannula 12. During observation of the spot, the cannula 12 is moved to bring the spot and the target location 46 on the vessel 44 in coincidence. The adjustment is completed when the intersection of the directions I and P and the target location 46 coincide.
When being adjusted, the cannula 12 according to the embodiment of
In a second step the catheter 26 is inserted. In this step the catheter 26 which is received in the cannula 12 is advanced through the cannula 12, e.g. with a piezo motor. Due to the guidance by the end portion 20 the catheter 26 exits the opening 22 in the insertion direction I such that the leading end of the catheter 26 moves through the intersection of directions I and P which coincides with the target location 46. Accordingly, at the target location 46 the catheter 26 penetrates the vessel 44.
In some embodiments the cannula 12 and the handle portion 14 are detachably connected, such that the cannula 12 may be disposable while the same handle portion 14 may be used again in further applications. Hence, in every application the instrument 10 may be used with a new cannula 12 to ensure that the cannula 12 is clean, flawless and/or sterile. Likewise to the cannula 12, also the catheter 26 may be disposable. Accordingly, the cannula 12 and the catheter 26, which may contain one or more drugs suitable for a respective treatment, can be replaced in combination. In this case, the entire combination of the cannula 12 and the catheter 26 corresponds to a disposable good or consumable. This allows ensuring an improved treatment both in terms of time and in terms quality.
For the specific application of ophthalmic surgery, the cannula 12 may have the following dimensions to which, however, the present invention is not restricted. The portion 36 of the first channel may have a diameter D1 (indicated in
The rear portion 16 of the cannula 12 may have a diameter D3 (indicated in
The second channel 32 may have a diameter D6 (indicated in
The pointing beam 48 may have a diameter D7 (indicated in
In preferred embodiments the pointing beam 48 has a diameter D7 which essentially corresponds to the diameter of the catheter 26. For the application of ophthalmic surgeries the pointing beam 48 may have a diameter D7 between 50 μm and 80 μm.
If the pointing beam 48 is not collimated, the spot size may serve as a measure for the distance of the cannula 12 from the ground.
While the present invention has been described with respect to specific examples and embodiments, it needs to be considered that the specific examples and embodiments are merely illustrative for the present invention and are not intended to limit the scope of the present invention which is defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15169828.9 | May 2015 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/062042 | 5/27/2016 | WO | 00 |
