Patent Application
20130123661
The present invention relates to a pressure detection assembly for determining pressure in a tissue cavity inspected by an endoscope, and an endoscope adapted with the assembly, and a method for adapting an endoscope.
Endoscopy is employed in many surgical procedures such as transurethral resection of the prostate/bladder, hysteroscopic procedures such as endometrial resection, fibroid resection, polyp resection, septoplasty, adhesiolysis and arthroscopic procedures. Increasingly, it is being deployed for neurosurgical procedures, to the extent that endoscopic intraventricular procedures are common in most neurosurgical departments.
In such procedures, a continuous flow endoscope is frequently used. Those skilled in the art would understand the structural composition of a continuous flow endoscope. Briefly, a continuous flow endoscope is adapted to allow rinse fluid simultaneously to enter and escape from a tissue cavity via separate entry and exit points, as a result of which positive fluid pressure is created inside the tissue cavity which distends the cavity.
A typical continuous flow irrigation endoscope comprises one or more fluidicly isolated lumens present inside an outer shaft. The outer shaft is typically a hollow cylindrical tube which has a distal end which enters a tissue cavity and a proximal end connected to a hub on which an inflow or outflow port is attached for the purpose of instilling or evacuating fluid from the cavity. The irrigation fluid is instilled via an inlet port. The instilled fluid travels through a rinse inlet lumen and enters the tissue cavity via the distal opening of the rinse inlet lumen. The waste fluid present inside the tissue cavity enters the distal opening of the rinse outlet lumen, and exits the endoscope via the outflow port attached at the proximal end of rinse outlet lumen.
An optic element (fibre, rigid or chip on tip) is placed inside an inspection lumen of the shaft in order to view the interior of the tissue cavity. An endoscopic instrument, such as a wire loop electrosurgical cutting loop, may be also placed within another lumen present in the shaft.
It was initially assumed that an open outlet channel would prevent a rapid build up of pressure within the tissue cavity. However, in practice, detached tissue pieces, larger than a critical size, present in the tissue cavity are unable to pass through the rinse outlet port leading to obstruction of the outflow channel which can provide an erroneous pressure reading, and pressure-build up. Additionally, the kinking of outflow tube occurs which can also distort the pressure reading. Raised intracranial pressure (ICP) during neurosurgical procedures is common according to the scientific literature, which can induce intracranial hypertension leading to cardiovascular complications, herniation syndrome, retinal bleeding, Terson's syndrome and excessive fluid resorption.
Direct measurement of pressure in the cavity is the gold standard, however, insertion of a separate catheter through a second burr hole for this purpose is clinically impractical and difficult to justify, particularly for the neurosurgeon. Consequently, pressure is presently measured at the proximal end of the endoscope at rinsing inlet and outlet as shown in
Pressure measurements at the proximal ends of the inlet and outlet can only provide valid estimations of static ventricular pressures i.e. if the rinsing inlet and outlet are closed simultaneously, and pressures are measured after a suitable interval to allow for equilibration of pressures. This is seldom clinically practicable, and it is especially impractical during occasions when high rinsing flows are required such as during brisk bleeding.
Various systems are described in the prior art for the measurement of pressure cavity pressure. For instance US 2009/182201 describes an outer sheath disposed with one or more channels through which a reusable pressure sensor can be inserted, which sheath is fitted over the outer body of an endoscope. The sheath increases the outer diameter of the endoscope, limiting its application in many techniques, including neurosurgery. Moreover, a sterilized sheath is difficult to apply over a sterilized endoscope aseptically. There is thus a need for dynamic pressure assessment that is clinically feasible to implement, which provides a more accurate measurement of actual pressure in the ventricle, can be applied easily aseptically and avoids the problems associated with blockages.
One embodiment of the invention is a pressure detection assembly (100) adapted for use with a continuous flow endoscope (200) provided with a rinse inlet lumen (234) connected to a rinse inlet port (254) said assembly (100) comprising:
One embodiment of the invention is a pressure detection assembly (100) adapted for use with a continuous flow endoscope (200) provided with a rinse lumen (232, 234) connected to a rinse port (250, 254) said assembly (100) comprising:
The rinse lumen (232, 234) may be the rinse inlet lumen (234) or the rinse outlet lumen (232), preferably the rinse inlet lumen (234). Accordingly the rinse port (250, 254) may be the rinse inlet port (254) or the rinse outlet port (250), preferably the rinse inlet port (254).
Another embodiment of the invention is an assembly (100) as described above, wherein:
Another embodiment of the invention is an assembly (100) as described above, wherein the indication of ambient pressure is conducted by the catheter (12) using hydrostatic force.
Another embodiment of the invention is an assembly (100) as described above, wherein:
Another embodiment of the invention is an assembly (100) as described above, wherein the indication of ambient pressure is comprises electrical signals conducted by the wires (17).
Another embodiment of the invention is an assembly (100) as described above, wherein:
Another embodiment of the invention is an assembly (100) as described above, wherein the indication of ambient pressure is comprises optical signals conducted by the optical fibres (17).
Another embodiment of the invention is an assembly (100) as described above, wherein the distal tip (30) of the elongated member (10) is configured for locating flush or recessed to the distal (30) tip of the rinse lumen (232, 234). The rinse lumen (232, 234) may be the rinse inlet lumen (234) or the rinse outlet lumen (232), preferably the rinse inlet lumen (234).
Another embodiment of the invention is an assembly (100) as described above, wherein the distal tip (30) of the elongated member (10) is configured for locating at a distance of 0 mm, 0.1 mm, 0.2 mm, 0.4 mm, 0.6 mm, 1 mm, 2 mm, 3 mm, 4 mm, 6 mm, 8 mm, or 10 mm proximal to the distal tip of the rinse lumen (232, 234) or endoscope shaft (220). The rinse lumen (232, 234) may be the rinse inlet lumen (234) or the rinse outlet lumen (232), preferably the rinse inlet lumen (234).
Another embodiment of the invention is an assembly (100) as described above, wherein the outer diameter of the elongated member (10) is adapted to substantially maintain the functioning of the rinse lumen (232, 234). The rinse lumen (232, 234) may be the rinse inlet lumen (234) or the rinse outlet lumen (232), preferably the rinse inlet lumen (234).
Another embodiment of the invention is an assembly (100) as described above, wherein the coupling (40) is configured to separate fluid access to the rinse lumen (234) from fluid access to the catheter (12) lumen (15). The rinse lumen (232, 234) may be the rinse inlet lumen (234) or the rinse outlet lumen (232), preferably the rinse inlet lumen (234).
Another embodiment of the invention is an assembly (100) as described above, wherein the coupling (40) comprises a Luer lock fitting.
Another embodiment of the invention is an assembly (100) as described above, wherein the diameter of the catheter (10, 12) is between 0.3 mm and 0.9 mm, preferably between 0.4 mm and 0.7 mm.
Another embodiment of the invention is an assembly (100) as described above, wherein the length of the catheter (10, 12) between the distal tip and the coupling is between 10 cm and 35 cm, preferably between 14 cm to 24 cm in length.
Another embodiment of the invention is an assembly (100) as described above, wherein the flow functioning of the rinse lumen is maintained when the fluid flow through the rinse lumen (234) at constant pressure is reduced by an amount equal to or less than 60% when the elongated member (10) is advanced therethrough.
Another embodiment of the invention is a kit comprising:
Another embodiment of the invention is a method for adapting a continuous flow endoscope (200) with a rinse lumen (232, 234) connected to a rinse inlet port (250, 254) to provide an ambient pressure measurement capability comprising the steps:
(a) providing a pressure detection assembly (100) as defined in any of claims 1 to 9,
(b) advancing the proximal end of the pressure detection assembly (100) through the rinse port (250, 254) of the endoscope 200, and
(c) engaging the coupling (40) with the rinse port (250, 254), thereby adapting the continuous flow endoscope (200) to provide an ambient pressure measurement capability.
The rinse lumen (232, 234) may be the rinse inlet lumen (234) or the rinse outlet lumen (232), preferably the rinse inlet lumen (234). Accordingly the rinse port (250, 254) may be the rinse inlet port (254) or the rinse outlet port (250), preferably the rinse inlet port (254).
Another embodiment of the invention is a method of preparing an assembly as defined above, comprising the step of attaching the fluidic coupling (40) to the shaft of the catheter (12) so as to allow separate fluid access to the rinse lumen (232, 234) and the catheter (12) lumen (15). The rinse lumen (232, 234) may be the rinse inlet lumen (234) or the rinse outlet lumen (232), preferably the rinse inlet lumen (234).
Another embodiment of the invention is a continuous flow endoscope (200) having an outer shaft that encloses a plurality of lumens, further comprising:
Another embodiment of the invention is a continuous flow endoscope (200) as described above, where the elongated member (10) has one or more of the features defined above.
Another embodiment of the invention is a continuous flow endoscope (200) as described above that is single use.
Before the present device and method of the invention are described, it is to be understood that this invention is not limited to particular devices and methods or combinations described, since such devices and methods and combinations may, of course, vary. It is also to be understood that the terminology used herein is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.
As used herein, the singular forms “a”, “an”, and “the” include both singular and plural referents unless the context clearly dictates otherwise.
The terms “comprising”, “comprises” and “comprised of” as used herein are synonymous with “having”, “including”, “includes” or “containing”, “contains”, and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. It will be appreciated that the terms “comprising”, “comprises” and “comprised of” as used herein comprise the terms “consisting of”, “consists” and “consists of”.
The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints.
Whereas the terms “one or more” or “at least one”, such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any or etc. of said members, and up to all said members.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art. All publications referenced herein are incorporated by reference thereto. All United States patents and patent applications referenced herein are incorporated by reference herein in their entirety including the drawings.
The articles “a” and “an” are used herein to refer to one or to more than one, i.e. to at least one of the grammatical object of the article. By way of example, “a port” means one port or more than one port.
The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1, 2, 3, 4 when referring to, for example, a number of articles, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of end points also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0).
The terms “distal”, “distal end”, “proximal” and “distal end” are used through the specification, and are terms generally understood in the field to mean towards (proximal) or away (distal) from the surgeon side of the apparatus. Thus, “proximal (end)” means towards the surgeon side and, therefore, away from the patient side. Conversely, “distal (end)” means towards the patient side and, therefore, away from the surgeon side. Herein, the “proximal (end)” of an element is denoted with reference sign 20, and the “distal (end)” of an element is denoted with reference sign 30.
In the passages herein, different embodiments or aspects of the invention are defined in more detail. Each embodiment and/or aspect so defined may be combined with any other aspect or aspects or embodiments unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.
In the following detailed description of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration only of specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilised and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.
The present invention, as exemplified in
According to one embodiment of the invention, as exemplified in
According to another embodiment of the invention, as exemplified in
According to another embodiment of the invention, as exemplified in
Advantageously, the assembly provides a measurement of ambient pressure at the distal end of the endoscope that accurately reflects the static pressure in the cavity of the intervention. By contrast, measurement at the rinsing inlet gives a severe overestimation of the true cavity pressure, and if clinicians were to respond to these pressures, this would unnecessarily impede the rinsing efforts of the surgeon. Measurement at the rinsing outlet gives a systematic severe underestimation of the true cavity pressure, which would delay crucial intervention. Pressure could be measured in a static mode, however, this would require pausing the flow of rinsing fluid. Since rinsing is essential to give the surgeon an unobscured view of the cavity, regular pausing impedes progress and increases operating times, so increasing the costs of interventions and the risk of infections. By employing a pressure detection assembly of the invention, which can be applied to an existing endoscope, the pressure measurement, which accurately reflects pressure in the cavity, can be measured accurately and reliably while the endoscope is rinsing i.e. fluid is flowing through the rinse inlet and rinse outlet. Since the invention can be applied to an existing endoscope, and utilise existing hydrodynamic measurement equipment when the elongated member 10 is a catheter 14, the costs of implementation are neglible.
Moreover, pressure in the cavity can be exquisitely controlled i.e. set to a pre-defined level and maintained at that level. This can be achieved using a closed-loop (feedback loop) system comprising one or more pumps and/or valves and a controller, which controller regulates said pumps and/or valves responsive to pressure measured using the pressure detection assembly of the invention 100, to maintain pressure at the predefined level. The closed loop system may be advantageously employed to deliberately increase pressure at the intervention site, which pressure increase expedites clot formation in the case of a hemorrhage. Controllably increasing pressure at the intervention site, particularly in the brain, is presently considered a risk to the extent that many surgeons will avoid it. Since the pressure detection assembly of the invention 100 provides such an accurate reading, procedures otherwise excluded as entailing too much risk, now become available through the present invention. Since an existing endoscope can be adapted, and existing pressure detection equipment employed, the costs of making new pressure-reliant techniques available is negligible.
When the elongated member 10 is a catheter 14, the costs of implementation are neglible. Moreover, the catheter 14 can be made a disposable item, while the endoscope is sterilized between uses. Since the catheter is provided as a removable and disposable item, problems with steam sterilization are avoided which arise from the lack of steam penetration within the catheter lumen. While steam sterilisation does not affect the endoscope as it is disposed with wider bore lumens, it would not be possible to sterilize the lumen of a catheter 14 inserted into the endoscope channel owing to its narrow diameter. Thus the disposable pressure detection assembly 100 of the invention overcomes this problem.
Advantageously, when the rinse inlet channel 234 is used, fresh rinse medium continually washes over the pressure detecting body, removing or preventing blockages or contamination with particles. The assembly 100 provides an economical solution to the problem, that can be deployed on existing endoscopes without significant adaptation.
The assembly 100 of the invention is configured for connection with the rinse lumen 232, 234 of an endoscope 200. The rinse lumen 232, 234 may be the rinse inlet lumen 234 or the rinse outlet lumen 232, preferably the rinse inlet lumen 234. The endoscope is preferably a continuous rinse endoscope. As explained elsewhere herein, a continuous flow endoscope is adapted to allow fluid simultaneously to enter and escape from a tissue cavity via separate entry and exit points. It is well known to the person skilled in the art. As a general guidance and with reference to
Each lumen 230, 232, 234 is open at the distal 30 end, the open end provided with an exit port 240, 242, 244. Said exit ports 240, 242, 244 are typically disposed as a bundle within the shaft 220 at the distal 30 tip. The proximal end 20 of the shaft 210 is attached to a hub 210. The hub 210 comprises a plurality of proximal coupling ports 250, 252, 254; each lumen 232, 230, 234 being in fluidic connection with one or more proximal coupling ports 250, 252, 254. In particular, the inspection lumen 230 is in fluidic connection with an inspection port 252, the rinse inlet lumen 234 is in fluidic connection with a rinse inlet port 254, and the rinse outlet lumen 232 is in fluidic connection with a rinse outlet port 250. The hub allows the dismountable attachment of a connector, valve, gauge etc to each port for servicing the requisite lumen. To this end, each port 250, 252, 254 may be provided with a connector such as a male or female screw thread connector. In
The elongated member 10 of the assembly 100 is configured for advancement through a rinse lumen 232, 234. The rinse lumen 232, 234 may be the rinse inlet lumen 234 or the rinse outlet lumen 232, preferably the rinse inlet lumen 234. As such, the elongated member 10 is flexible, but stiffened to provide pushability through the lumen 232, 234 without kinking or buckling. Typically it has a cylindrical transverse sectional profile, though other profiles are not excluded such as ovoid or polygonal. The elongated member 10 of the assembly 100 is further configured to conduct an indication of ambient pressure generated by the pressure detecting body 50 to its proximal 20 end. The type of conductance is dependent on the pressure detecting body 50. When pressure detecting body 50 comprises a port 14 (
The length of the elongated member 10 is such that the pressure detecting body 50 is able to advance through the rinse lumen 232, 234 towards the distal 30 tip of the endoscope 100. Preferably, the length is such that the pressure detecting body 50 is in a recessed or flush position relative to the distal 30 tip of the rinse lumen 232, 234 or the endoscope shaft 10, particularly when the coupling 40 of the assembly 100 is connected to the rinse port 250, 254 of the endoscope 200. While a recessed or flush juxtaposition is preferred, it is within the scope of the invention that the length of the elongated member 10 allows it to protrude relative to the distal 30 tip of the rinse lumen 232, 234 or the endoscope shaft 10, for example, by 1, 2 or 3 mm. It will be appreciated that the length of the protrusion is minimised to avoid a risk of damaging the tissue under intervention.
The luminal length, LL (
As a general guidance, the luminal length, LL (
The maximum outer diameter OD (
Additionally, it is configured to substantially maintain the flow functioning, more particularly a proper functioning, of the rinse lumen i.e. the flow of rinsing medium through the rinse inlet lumen 234 or through the rinse outlet lumen 232 is not substantially hindered when the elongated member 10 is deployed in the endoscope. According to one embodiment of the invention, the maximum outer diameter OD (
Determining whether the flow of rinsing medium through the rinse inlet lumen 234 or through the rinse outlet lumen 232 is not substantially hindered when the elongated member 10 is deployed in the endoscope can be determined by flow rate tests. The fluid flow rate in the rinse lumen (232, 234) is measured at constant pressure without and with the elongated member 10 deployed therein. Should the flow rate drop by a certain amount, then the elongated member 10 plays a substantially hindering role. Typically, the flow functioning of the rinse lumen is maintained when the fluid flow at constant pressure is reduced by 0%, or an amount equal to or less than 5%, 10%, 20%, 30%, 40%, 50%, 60% when the assembly is coupled to the rinse lumen, more particularly, when the elongated member 10 is deployed therein, compared to when it is absent.
When the pressure detecting body 50 comprises a distal open port 14 (
As a general guidance, maximum outer diameter, OD, of the catheter 12 shaft (
The inner diameter, ID, of the catheter lumen 15 (
The length of the catheter 12 shaft is such that the distal open port 14 is able to pass through a rinse lumen 232, 234 towards the distal 30 tip of the endoscope 100. Preferably, the length is such that the distal open port 14 is located in a recessed or flush position relative to the distal 30 tip of the rinse inlet lumen 232, 234 or the endoscope shaft 10, particularly when the coupling 40 of the assembly 100 is connected to the relevant rinse port 250, 254 of the endoscope 200.
The dimensions of the luminal length, LL (
The luminal length, LL (
The wall of the catheter shaft 12 may be formed from any suitable non-expandable material such as polyethylene, polypropylene, or polyimide.
When the pressure detecting body 50 comprises an electrical pressure transducer 16 (
As explained later below, the proximal 20 end of the sheath body is in sealed connection with a coupling 40 for an endoscope rinse port 250, 254, which may be the rinse inlet port 254 or the rinse outlet port 250, preferably the rinse inlet port 254. The coupling 40 is configured to seal the proximal 20 region of the sheath 14 body with the selected rinse port 250, 254 of the endoscope 200. More in particular, it is configured to allow electrical wires 17 connecting the transducer to exit the sheath 14, while providing a separate fluidic connection to the rinse port 250, 254 of the endoscope 200 hub 210.
As a general guidance, maximum outer diameter, OD, of the sheath 14 (
The dimensions of the luminal length, LL (
The luminal length, LL (
The wall of the sheath 14 may be formed from any suitable material such as polyethylene or polypropylene, polyimide, polyether ether ketone (PEEK).
When the pressure detecting body 50 comprises a light-reflective element (LRE) 70 (
As explained later below, the proximal 20 end of the sheath body 14 is in sealed connection with a coupling 40 for an endoscope rinse port 250, 254, which may be the rinse inlet port 254 or the rinse outlet port 250, preferably the rinse inlet port 254. The coupling 40 is configured to seal the proximal 20 region of the sheath 14 body with the relevant rinse port 250, 254 of the endoscope 200. More in particular, it is configured to allow optical fibres 72 connecting the LRE 70 to exit the outer sheath 14, while providing a separate fluidic connection to the relevant rinse port 250, 254 of the endoscope 200 hub 210.
As a general guidance, maximum outer diameter, OD, of the sheath 14 (
The dimensions of the luminal length, LL (
The luminal length, LL (
The wall of the sheath 14 may be formed from any suitable material such as polyethylene or polypropylene, polyimide, polyether ether ketone (PEEK).
The assembly 100 is provided with a coupling 40 adapted for dismountable connection to the rinse port 250, 254 of the endoscope 200 hub 210. The rinse port 250, 254 may be the rinse inlet port 254 or the rinse outlet port 250, preferably the rinse inlet port 254. The coupling 40 is positioned substantially in the proximal 20 half, or at the proximal end of the elongated member 10. As exemplified in
At the distal end 30 of the coupling 40 is an open connector 42 in fluidic connection with the chamber 46, adapted to engage with a rinse port 250, 254 of the endoscope hub 210. The elongated member 10 is disposed through this open connector 42. The connector 42 is preferably essentially tubular, hollow and threaded; more preferably it is a male Luer push connector in concentric alignment with an outer rotating female screw thread.
The coupling 40 is also provided with a proximal port 44. The proximal port 44 is positioned toward the proximal 20 end of the coupling 40. Preferably, a central axis of the port 44 is in co-axial alignment with a central axis of the connector 42.
According to a preferred aspect of the invention, the body of the proximal 20 portion or end of the elongated member 10 is disposed through the proximal port 44. This arrangement facilitates passage of the elongated member 10 through both the connector 42 and the port 44 without the requirement to bend or shape the elongated member 10. The proximal port 44 is fluidicly sealed around the outer body of the elongated member 10. This may be achieved using, for example, a plug 48 of silicone or rubberized polymeric resin molded around the outer body of the elongated member 10. In situ on the endoscope hub 210, the chamber 46 of the coupling 40 is in sealed fluidic connection with the rinse inlet lumen 234. Since the proximal end or part of the elongated member 10 passes through the proximal port 44 and the proximal port 44 is sealed there around, the chamber 46 is fluidicly isolated from the proximal 20 end of the elongated member 10. The proximal port 46 may be extended proximally 20 to include a connector 45 for dismountable attachment to an external device. The connector may be, for example, a Luer connector for dismountable attachment to a pressure gauge.
The embodiment shown in
Alternatively, however, the coupling 40 may further be provided with a side port 49 in fluid connection with the chamber 46 as exemplified in
It is within the scope of the invention that the elongated member 10 passes either through the proximal port 44 as exemplified in
The coupling 40 may be provided in slidable or fixed relation to the elongated member 10. Generally, but not necessarily, it will be in fixed relation when the elongated member 10 is a catheter 12 that can be trimmed from the distal end so as to change its luminal length LL according to the length of the relevant rinse lumen 232, 234 of the endoscope 200. Generally, but not necessarily, it may be in sliding relation, when the pressure detecting body 50 is an electrical pressure transducer 16 and thus the possibility to truncate the elongated member 10, formed of conducting wires, to match the length of the rinse lumen 232, 234 of the endoscope 200 cannot be realised. The coupling 40 may be provided in fixed relation by utilizing the sealing plug 48 of rubberized or silicone material to frictionally or adhesively engage with the outer wall of the elongated member 10. The coupling may be provided in lockable, slidable relation by utilizing the plug 48 of rubberized or silicone material as a sliding seal that engages with a friction-reduced (e.g. Teflon coated) outer wall of the elongated member 10. It may be locked by any means, such as a locking pin or screw.
Preferably, the coupling 40 is a standard three-branch, Y-shaped hub, two branches of the hub each provided with a female Luer push fitting around which a male thread is disposed, and one branch of the hub provided with a male Luer push-fitting about which a female rotating threaded collar is provided.
The pressure detecting body 50 is a structure located at the distal 30 end of pressure detecting body 50 onto which the pressure in the environment of the cavity is applied. Using either hydrostatic transmission (
According to one embodiment, the pressure detecting body 50 comprises a distal port 14 (FIG. 4)—that is an opening in the shaft of the catheter—through which non-compressible fluid is displaced responsive to pressure in the cavity, which displacements are transmitted via a catheter 12 lumen to a pressure gauge connected to the proximal end of the catheter. The distal port 14 may be open or may be sealably covered with a flexible, expandable membrane. The distal port 14 is preferably, but not necessarily, located at the distal tip of the catheter 12 i.e. it is an end hole. Alternatively or in addition, it may be located on the side wall of the catheter but no more than 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm or 7 mm from the distal 30 tip of the catheter 12. There may be one or more distal ports 14; there are several ports, they will preferably be confined to the aforementioned distances from the distal 30 tip of the catheter 12. The pressure detecting body 50 can be regarded as a portion of the catheter 12 located at its distal 30 end onto which the pressure in the environment of the cavity is applied, and is equalized with pressure within the lumen via the distal port 14.
According to another embodiment, the pressure detecting body 50 may be an electrical pressure transducer 16 (
According to another embodiment, the pressure detecting body 50 may be a light-reflective element (LRE), such as a mirror, deformable on the application of pressure (
It is within the scope of the invention that the elongated member 10 is provided as a further channel to the endoscope. In other words, an endoscope comprises an additional channel having the same properties as the elongated member 10, in particular, the catheter, and the associated pressure detecting body 50. The additional channel may not necessarily be disposed within the rinse inlet lumen 234; it may be provided alongside. The endoscope is preferably single use; the single use endoscope avoids the need to sterilize the elongated member 10 which is technically difficult when it is a catheter 12 having a small diameter inner lumen.
One embodiment of the invention is continuous flow endoscope 200, as described elsewhere herein, having an outer shaft that encloses a plurality of lumens, further comprising:
Another embodiment of the invention is a continuous flow endoscope as described above, where the elongated member 10 has one or more of the features defined elsewhere herein.
One embodiment of the invention is a kit comprising a continuous flow endoscope 200 as described herein, and a pressure detection assembly 100 as described herein. The luminal length, LL (
Shown in
Another embodiment of the invention relates to a method for adapting a continuous flow endoscope 200 having a rinse inlet lumen 234 to provide an ambient pressure measurement capability. The method comprises the step of attaching the pressure detection assembly 100 of the present invention to the continuous flow endoscope according to the embodiments already described herein. In particular, it may comprise the steps:
(a) providing a pressure detection assembly 100 of the present invention,
(b) advancing the proximal end of the pressure detection assembly 100 through a rinse port 250, 254 of the endoscope 200,
(c) engaging the coupling 40 with the rinse port 250, 254, thereby adapting the continuous flow endoscope 200 to provide an ambient pressure measurement capability.
The rinse port 250, 254 may be the rinse inlet port 254 or the rinse outlet port 250, preferably the rinse inlet port 254.
The elongated member 10 is dimensioned to position the distal tip of the pressure detecting body 50 flush or recessed with respect to the distal tip of a rinse lumen 232, 234 or the endoscope shaft 200. Where the elongated member 10 is a catheter, the lumen may be filled with an incompressible fluid, such as aqueous saline solution. Filling is effected by using, for example, a syringe, a saline bag, or fluid pump.
Another embodiment of the invention relates to a method for the measurement of ambient pressure within a tissue cavity being investigated with a continuous flow endoscope by the use of a transendoscopic pressure measurement probe. The transendoscopic pressure measurement probe is preferably comprised in a pressure detection assembly 100 of the present invention.
A custom-made model of a human head was used for the in-vitro measurements. The head was completely filled with 0.9% saline solution and sealed hermetically. A precoronal burr hole was made and closed with a rubber seal. A Caemaert endoscope (Richard Wolf, Knittlingen, Germany) was installed through the seal and fixated with a pneumatic holding device (Aesculap, Tuttlingen, Germany). The inflow- and outflow channels of the endoscope had an internal diameter of 1.67 mm and a length of 350 mm. A second burr hole was made and sealed with a rubber seal. A standard external ventricular drain with an internal diameter of 1.3 mm (Integra NeuroSciences, Plainsboro, N.J., USA) was positioned through the seal into the fluid-filled cavity. The rinsing system was installed in the standard manner for neuro-endoscopic procedures: 3-way stop cocks (Discofix®, B. Braun, Melsungen, Germany) were connected at the rinsing inlet and at the rinsing outlet for pressure measurement. Pressure transducers (PMSET 1DT-XX Becton Dickinson Critical Care Systems Pte Ltd, Singapore) were connected to the three-way stopcock and to the ventricular catheter via low compliance pressure tubing. All pressure transducers were flushed with saline, and zeroed at the level of the external acoustic meatus.
The irrigation system was installed as in routine clinical practice: a pressurised flush bag of saline was connected to the valve at the inflow of the endoscope via an infusion set with standard flow regulator. The bag was placed under a constant pressure of 300 mmHg using a Ranger Pressure Infusion Systems (Arizant Inc., MN, USA). An IV infusion set (Intrafix Primeline I.S., B.Braun, Melsungen, Germany) was used as outflow tube. The luer-lock was connected to the 3-way stopcock at the rinsing outlet of the endoscope, and the opposite end was positioned at the level of the burr hole. For precise determination of the flow rate during pressure measurements, the effluent was collected into an accurate measuring glass for exactly 60 seconds.
All pressure transducers were connected to an S5 monitor (GE Health Care, Helsinki, Finland), which displayed the analogue pressure waveforms in real time, digitised the signals at a sampling frequency of 100 Hz, and transmitted them to a PC computer for electronic storage using S5 Collect® software (GE Health Care, Helsinki, Finland).
Four separate experiments were performed. At the start of each experiment, the endoscope was introduced into the ventricular cavities, and a rinsing flow at “fast dripping speed” was initiated, as per routine clinical practice. After measurement of baseline pressures, the flow was increased in small steps, using the flow regulator, until a flow of 210 ml/min was reached. After each change in flow, an equilibration time was observed until a steady plateau pressure was reached. For each flow rate the plateau pressure was recorded. The rinsing fluid used was saline 0.9%.
Pressure measurement was made according to the prior art i.e. the ventricular pressures were measured via the ventricular catheter and compared with the pressures measured at the rinsing inlet and rinsing outlet. The result of the measurement is shown in
In a second step, the equipment set-up was modified to enable pressure measure at the distal end of the lumen of the endoscope. A connecting piece (Rotating Male Hub Tuohy Borst with Sideport nr 80346, Qosina, Edgewood, N.Y., USA) was attached to the endoscope, and a Codman Microsensor™ tip sensor (Johnson & Johnson Professional, Raynham, Mass., USA) was introduced through the rinse inlet lumen and advanced so that it was located 1 mm proximal of the distal end of the endoscope. The tip sensor was also connected to the S5 monitor. The pressures it recorded were then compared with the pressure in the ventricle and at the rinsing outlet.
The second protocol was repeated but instead of the Codman tip sensor, a Portex epidural catheter (Smiths Medical, NH, USA) was used. Before placement the distal 2.5 cm of the catheter, containing side holes, was removed to provide a catheter an end hole. The catheter was then slid through the inflow-channel until the tip was 1 mm proximal to the distal end of the endoscope.
The first measurement protocol was repeated but with a short Caemaert endoscope which also has a rinsing channel diameter of 1.67 mm, but a shaft length of 240 mm (as opposed to 350 mm in the standard instrument).
In the subsequent analysis, for each flow, the steady-state pressures at the different measuring points were graphically represented. The relationship between flow and pressure were determined by linear regression. The difference between the pressure in the ventricle—which is considered the gold standard—and the other pressure measurement sites was calculated for each flow rate.
The Reynolds number was calculated for each flow rate to evaluate whether laminar flow was likely. For each flow rate, at which laminar flow was likely (up to 180 ml/min), the measured pressure gradients were compared with pressure gradients predicted by the Hagen-Poiseuille equation [1]:
Data were normally distributed and are presented as mean (SD).
The evolution of the ventricular pressure during initiation of rinsing is shown in
The pressure measured at the different points in relation to the flow is represented in
The pressure gradients between rinsing inlet (I), intraventricular (V), and rinsing outlet (O) related to the flow is shown (
Both the Codman tip sensor (
The short Caemaert Endoscope (
The Reynolds number, calculated for the dimension of the endoscope is 663 at a flow of 50 ml/min up to 2650 at a flow of 200 ml/min. At a flow of 61 ml/min, the measured pressure gradient between rinsing inlet, intraventricular, and rinsing outlet was 18 mmHg and 19 mmHg respectively, while the theoretical pressure gradient, calculated by Poiseuille's equation is 17 mmHg. At a flow of 130 ml/min the measured pressure gradients are 31 mmHg and 31 mmHg; the calculated is 27 mmHg. At an extremely high flow of 210 ml/min the measured pressure gradients are 81 mmHg and 85 mmHg, while the calculated gradient is 57 mmHg.
After initiation of rinsing (flow 30 ml/min) in the model, only a transient period of intracranial hypertension was observed. The evolution of ventricular pressure changes during this period shows four phases (
Transendoscopic monitoring of the pressure at the distal tip of the endoscope using an electronic Codman tip sensor provided a very accurate assessment of the ventricular pressure (and thus of the ICP). Of course, the application of an extra monitoring device and the use of a disposable electronic tip sensor will introduce some practical and financial considerations. In order to find a cheaper and more practical method of transendoscopic pressure monitoring, we replaced the tip sensor with a fluid-filled epidural anaesthesia catheter connected to a standard pressure transducer outside of the head. The tip of the catheter was placed at the same location as the tip sensor (1 mm proximal to the distal end of the endoscope). When intact epidural catheters are used, a systematic overestimation of the ventricular pressure occurs, because they have lateral side holes 7, 11 and 15 mm from the distal end, and thus the measured pressure reflects the pressure 15 mm proximal to the distal end of the endoscope. In the current study measurements were thus performed with a modified catheter containing only an end hole, and with this catheter the transendoscopic pressure measurements compared highly favourably with ventricular pressure measurements (maximal error of ±1 mmHg).
Because the induced intracranial hypertension only becomes clinically relevant at faster rinsing flow rates—above 50 ml/min—and the rinsing flow is relatively stable, the compliance of the intracranial system is of minimal influence on the observed pressure values. Based on the Monro-Kellie hypothesis—that with an intact skull, the sum of the volumes of the brain, the CSF and the intracranial blood is constant—the capacity for expansion of the intraventricular volume during fast rinsing flow rates is limited to the intracranial blood volume. During gradual flow rate increases, the induced blood volume displacement caused by changes in rinsing pressure is minimal compared to rinsing volumes. This is confirmed by our observation that after adjustment of the rinsing speed, the pressure-waveform stabilizes almost immediately. Nevertheless, when the pressure is increased rapidly and severely (
The findings of this laboratory-based assessment suggest that clinically significant pressure gradients across the endoscope are generated during rinsing. These gradients are generated by dynamic resistances in the rinsing channels (Poiseuille law). Measurement at the rinsing inlet gives a severe overestimation of the true ICP (up to 50 mmHg), and if clinicians were to respond to these pressures, this would unnecessarily impede the rinsing efforts of the surgeon. Measurement at the outflow point gives a systematic severe underestimation of the true ICP (up to 50 mmHg), which would delay crucial intervention. Transendoscopic measurement of the pressure at the distal end of the endoscope accurately reflects the static ventricular pressure. There was no significant difference in the pressure measured at the tip of the endoscope using a Codman tip sensor (pressure transducer) and an epidural catheter.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10170794.1 | Jul 2010 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP11/62805 | 7/26/2011 | WO | 00 | 1/25/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61367795 | Jul 2010 | US |
