WO2011009224A2

WO2011009224A2 - Administration device with a means for sensing changes in pressure

Info

Publication number: WO2011009224A2
Application number: PCT/CH2010/000181
Authority: WO
Inventors: Edgar Hommann; Eric Hattler; Rolf Marggi; Michael Weibel; Peter Michel
Original assignee: Tecpharma Licensing Ag
Priority date: 2009-07-20
Filing date: 2010-07-15
Publication date: 2011-01-27
Also published as: CH701492A1; WO2011009224A3

Abstract

A device is disclosed for administering a liquid product, the device having a pressure sensing means for identifying occlusion. This means comprises a deformable element (272), for example in the form of a membrane, and a transmission element (273), for example in the form of a plunger. A fluid in the device, in particular a hydraulic fluid, acts on the deformable element (272) in such a way that the deformable element transmits a pressure-related force to the transmission element. This pressure-related force can easily be mechanically detected in order to identify an occlusion.

Description

TITLE

Administration device with a means for sensing changes in pressure

TECHNICAL FIELD

The present invention relates to a device for administering a liquid product, in particular a medicament in liquid form. A device of this type will be referred to hereinafter as an administration device for short. PRIOR ART

In various medical conditions, it may be necessary to administer a medicament in liquid form, for example an insulin preparation or a blood-thinning medicament such as heparin, to a patient over a relatively long period of time. Compact, portable, body-external administration apparatuses, which the patient wears close to his body at all times, are known for this purpose .

In order to reliably supply the patient with the medicament, it is essential that malfunctions, which can lead to an undersupply of the medicament or to the administration of the medicament being suspended altogether, be identified effectively and securely and lead to an alarm being triggered and/or to the apparatus being switched off. A malfunction of this type can in particular be caused by the occurrence of a clogging (occlusion) of a liquid-conveying line, for example of the infusion set.

WO 2008/106810 discloses a modular administration apparatus having a reusable base unit (reusable part) and a disposable cartridge (disposable part) . The base unit contains a drive unit with an electric motor, a gear mechanism and an entrainer as well as the comparatively expensive and complex components for operating and controlling the apparatus. The cartridge contains a carpule containing the product and a hydraulic system. When the drive unit is activated, this causes a piston of the hydraulic system to be advanced, so that the hydraulic fluid is displaced from a hydraulic reservoir into a displacement reservoir adjoining the carpule piston. This in turn causes the piston of the carpule to be advanced and the product to be ejected. An occlusion will manifest itself in a markedly rising pressure in the hydraulic system. In order to identify occlusions, the hydraulic system has a blind channel in which a spring-loaded slide is guided. When a threshold pressure in the hydraulic system is exceeded, the slide is displaced counter to the spring force. However, this pressure monitoring means is comparatively complex and as a result costly to produce.

A basically very similarly constructed modular administration apparatus is disclosed in WO 2008/106805. In this administration apparatus, a rise in pressure in the hydraulic reservoir is detected by guiding the piston of the hydraulic system in a guide element, which is displaced counter to a spring force and in the opposite direction to the direction of advancement of the piston when a threshold pressure is exceeded. This pressure monitoring means is also comparatively complex.

WO 00/72900 discloses a gas-operated infusion apparatus. The infusion apparatus comprises a gas generator with a pressure sensor which is formed by an electrically conductive, elastomeric membrane. When an occlusion causes the pressure in the gas generator to rise, the membrane protrudes outwards through an opening. As a result, the membrane enters into an electric contact with an electrode, so that a circuit is closed through the membrane. This solution has the drawback that the membrane has to be electrically conductive and can also easily become damaged.

EP 1 818 664 discloses an infusion apparatus with an infusion set, in the liquid path of which a deformable membrane is arranged. The membrane is deformed when the pressure in the liquid path rises. This deformation is detected optically in a contactless manner. This solution has the drawback that, on the one hand, the occlusion is identified only in the infusion set. As a result, occlusions occurring upstream of the membrane cannot be identified. In addition, optical detection is relatively complex and requires precise calibration. In addition, before the infusion set is assembled, the membrane is externally accessible without protection and can therefore easily become damaged. Direct or indirect detection of the deformation of a deformable element is also disclosed in US 4,950,244, WO 03/074121, WO 2008/144693 or US 2006/178633.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an administration device allowing simple and secure detection of occlusions. The occlusion detection means is also to be robust and protected from damage.

These and further objects are achieved by an administration device having the features of Claim 1. Preferred embodiments are specified in the dependent claims.

A device for administering a liquid product is therefore disclosed, the device comprising:

a housing; - a fluid reservoir which is arranged in or on the housing, is adapted to receive a fluid and is adapted to have a pressure applied to it in order to eject the liquid product from the device; and

a deformable element (preferably secured to the housing) which is arranged and configured in such a way that the pressure acting in the fluid reservoir exerts a pressure-related force on the deformable element. In order to be able to detect more simply and more reliably the pressure-related force acting on the deformable element and in order to protect the deformable element from damage, the device comprises a transmission element which is movable relative to the housing and is operatively connected to the deformable element in such a way that the pressure-related force can be transmitted substantially (i.e. apart from frictional forces, deformation forces of the deformable element and other losses) from the deformable element to the transmission element. This pressure-related force can easily be mechanically detected or measured by a detection means. The deformable element and the transmission element therefore jointly form a pressure sensing means, the position of the transmission element being an indicator of the fluid pressure in the fluid reservoir . The deformable element is preferably resiliently deformable, so that it opposes a rise in pressure with a resilient counterforce. Particularly preferably, the deformable element is configured as a resilient membrane preferably having in the unloaded state a substantially planar region which bulges in the event of changes in pressure. However, the deformable element can also have a different shape and, for example, be bulged in a dome-like manner or configured in a bag-like manner even when in the unloaded state. The deformable element may be deformable in a substantially force-free manner. The deformable element is preferably in direct contact with the fluid in the fluid reservoir. In preferred embodiments, the pressure-related force acting on the transmission element is continuously dependent on the fluid pressure, in any desired position of the transmission element, provided that the transmission element is located within a predefined range of positions. Preferably, the pressure-related force is only mildly dependent on the position of the transmission element, particularly preferably substantially (i.e. apart from the resilient restoring force of the deformable element and of losses) independent of the position of the transmission element. This can in particular be achieved in that the normal area which extends perpendicularly to the direction of movement of the transmission element, which is covered by the deformable element and over which the fluid acts on the deformable element does not change during deformation of the deformable element. This allows the pressure-related forces acting on the transmission element to be reliably measured by a detection means even when there are tolerances in the positioning of the detection means. Although such tolerances may then lead to an altered position of the transmission element, they lead to no or only a slight change in the pressure-related forces acting on the transmission element.

In preferred configurations, the device has a channel with a first and a second end, the first end of the channel opening into the fluid reservoir and the second end of the channel opening into a receiving space which is at least partly delimited by the deformable element. In this case, the deformable element therefore does not directly delimit the fluid reservoir, but delimits a space communicating with the fluid reservoir through the channel. This allows the deformable element to be arranged at a suitable position of the device, at which detection of the transmitted forces is easily possible. In this case, the cross section of the channel is selected so as to be sufficiently large that no significant drop in pressure takes place over the length of the channel, i.e. the fluid pressure is substantially equal at the two ends of the channel. However, in alternative configurations, it is also conceivable for the deformable element to directly delimit a part of the fluid reservoir.

This configuration with a channel allows an alternative embodiment in which the pressure-related force acting on the transmission element is discontinuously dependent on the fluid pressure, in particular, increases abruptly when a threshold pressure is exceeded for the first time. This is made possible by configuring the pressure sensing means as follows:

- The deformable element has an area which is larger than the cross-sectional area of the channel at its second end.

- As long as the pressure in the fluid reservoir has not exceeded a threshold pressure, the deformable element completely closes the channel at its second end.

When the threshold pressure is exceeded for the first time, the deformable element is deformed in such a way that it releases the second end of the channel. As a result, the fluid pressure now acts on a region of the deformable element, the area of which is larger than the cross-sectional area of the channel at its second end.

As a result, after the threshold pressure has been exceeded, a higher pressure-related force suddenly acts on the deformable element, so that the deformable element continues to be deformed until a counterforce, for example the resilient counterforce of the deformable element or a stop limiting the movement of the transmission element, prevents further deformation. When the threshold pressure is exceeded for the first time, the pressure measuring means therefore displays to a certain extent binary behaviour, with a comparatively marked change in force acting on the transmission element. The transmission element is preferably movably connected to the housing. It is preferably dimensionally stable (i.e. essentially rigid). The transmission element is preferably configured so as to be guided, in particular displaceable, relative to the housing. Preferably, the transmission element may be linearly guided, i.e. be displaceable in relation to the housing in a pure translatory movement. However, the transmission element can for example also be pivotable in relation to the housing and for this purpose be articulated to the housing at one end. It is also conceivable for the transmission element to be connected to the housing via a resilient connection, for example via a resilient lever arm. However, the transmission element is preferably a plunger which is guided so as to be displaceable relative to the housing and is arranged in such a way that it is displaceable as a result of a change in shape of the deformable element. In a preferred configuration, the housing has a guide region with an inner side pointing towards the interior of the housing and an outer side pointing towards the exterior of the housing. This guide region is preferably produced as a stand-alone guide element separate from the housing, but can also be formed in one piece with the housing. The resilient element is then arranged on the inner side of the guide region and the transmission element is arranged in an opening of the guide region in such a way that it at least partly covers the deformable element and that it is movable in the opening as a result of a deformation (change in shape) of the deformable element in or counter to a direction pointing towards the outer side of the guide element . The fluid reservoir, the pressure of which is monitored, is preferably not a product reservoir as such, in which the liquid product to be administered is accommodated, but rather a hydraulic reservoir which is filled with a hydraulic fluid (in particular an incompressible hydraulic liquid) . The device then also has a product container in order to receive the liquid product;- the product container is arranged in such a way that the pressure can be transmitted from the hydraulic reservoir to the product container in order to eject the liquid product from the product container. However, in alternative configurations, it is also possible to directly monitor the pressure in the product container or in a feed or discharge line thereof, for example in the tube of an infusion set, and the fluid, the pressure of which is sensed, is therefore the liquid product itself. The administration device specified hereinbefore can advantageously be configured as a disposable cartridge ("disposable module") for use in a semi-disposable apparatus. For this purpose, the administration device interacts with a reusable base unit ("reusable module") containing the comparatively expensive and complex components for driving and controlling the apparatus. The detection of the pressure-related force acting on the transmission element then takes place in the base unit .

The invention therefore also relates to a device for administering a liquid product, comprising:

- a reusable base unit with a drive means for generating a drive movement and if appropriate with a control means for controlling the drive means; and

- a device of the type specified hereinbefore in the form of an exchangeable cartridge which is detachably connectable to the base unit and which has a driven element which is configured to interact with the drive means in order to transmit the drive movement from the base unit to the cartridge and to apply a pressure to the fluid reservoir,

- the base unit having a detection means which is configured to detect the pressure-related force acting on the transmission element of the cartridge.

The detection means therefore mechanically cooperates with the transmission element. The detection means is configured and arranged in such a way that the pressure-related force acting on the transmission element can be transmitted to the detection means.

The detection means preferably has at least one element having an electrical property which is variable continuously or at least in a plurality of steps as a function of the pressure-related force acting on the transmission element, in particular one of the following elements:

- a piezoelectric sensor which is configured to emit an electric signal, in particular a piezoelectrically generated voltage, when the position of the transmission element changes; or

- a strain gauge which is configured to change an electrical property, in particular its electrical resistance, during a deformation and which is arranged in such a way that it is deformable as a result of a change in position of the transmission element. Alternatively, use may also be made of a detection means which has an element having an electrical property which is binarily variable as a function of the pressure-related force acting on the transmission element, in particular a snap disc or an electric switch with electric contacts, the snap disc or the switch being arranged in such a way that the electric contacts can be opened or closed as a result of a change in position of the transmission element. The control means is then electrically connected to the detection means in order to ascertain the variable electrical property and to derive therefrom control signals, in particular signals for incrementing a counter, signals for emitting an optical and/or acoustic and/or vibratory alarm signal, signals for ending the drive movement, etc.

In an advantageous configuration, the base unit and the cartridge are configured so as to be slidable one inside the other in a longitudinal direction in order to connect the cartridge to the base unit. In this case, it is advantageous if the position of the transmission element changes substantially transversely to the longitudinal direction, as it is easier to keep tolerances low in the transverse direction than in the longitudinal direction.

An arrangement of this type is also advantageous when the fluid acts directly on the transmission element

(for example when the transmission element is guided to the housing as a displaceable piston in a sealing manner) or when the pressure-related force is transmitted to the transmission element in a manner other than via a deformable element. The present invention therefore also relates to an administration apparatus for administering a liquid product, having: a reusable base unit with a drive means for generating a drive movement; and

- a cartridge which is detachably connectable to the base unit and has a housing, with a fluid reservoir arranged in or on the housing for receiving a fluid and with a driven element which is configured to interact with the drive means in order to transmit the drive movement from the base unit to the cartridge and to apply a pressure to the fluid reservoir in order to eject the liquid product from the cartridge,

the base unit and the cartridge being configured so as to be slidable one inside the other in a longitudinal direction in order to connect the cartridge to the base unit,

the cartridge having a movable transmission element in the form of a displaceable plunger to which a pressure-related force can be transmitted as a result of the pressure of the fluid in the fluid reservoir, and

the base unit having a detection means which is configured to detect the pressure-related force acting on the transmission element, and

- the transmission element being displaceable substantially transversely to the longitudinal direction. Preferably, also in this case the device has a channel with a first and a second end, the first end of the channel opening into the fluid reservoir and the second end of the channel opening into a receiving space having a larger cross section than the channel, and the transmission element is then arranged on the receiving space in such a way that the fluid located in the receiving space directly or indirectly exerts the pressure-related force on the transmission element. In configurations in which the transmission element moves transversely to the direction in which the base unit and the cartridge are telescoped, operational safety can be further increased if the base unit has at least one fixing element in a region adjacent to the detection means and if the cartridge has at least one fixing structure which is complementary thereto in order to fix the base unit and the cartridge relative to each other with respect to a direction transverse to the longitudinal direction in the region of the detection means.

In particular, the fixing element of the base unit can be configured so as to protrude in the longitudinal direction, for example in a pin-shaped manner, and the fixing structure of the cartridge can have an opening into which the fixing element can be inserted in the longitudinal direction. However, it goes without saying that an inverse arrangement is also possible in which the fixing structure protrudes from the cartridge and engages with an opening of the base unit. Other configurations of the fixing are also possible.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will be described hereinafter with reference to the drawings which are intended merely for illustrative purposes and are not to be interpreted as entailing any limitation. In the drawings:

Fig. 1 is a perspective view of a disposable cartridge

("disposable module");

Fig. 2 is a central longitudinal section through the cartridge;

Fig. 3 is a cross section through the cartridge in the plane III-III;

Fig. 4 is an enlarged illustration of the detail A from

Fig. 2;

Fig. 5 is a highly simplifying, schematic illustration of a reusable base unit ("reusable module") in a central longitudinal section;

Fig. 6 is a perspective view of the base unit;

Fig. 7 is an enlarged illustration of the detail B from Fig. 5;

Fig. 8 is a central longitudinal section through the complete, assembled administration apparatus;

Fig. 9 is a perspective view of the administration apparatus;

Fig. 10 is an enlarged illustration of the detail C from Fig. 8;

Fig. 11 is a detail view of an administration apparatus with a detection means with a piezo element; Fig. 12 is a detail view of an administration apparatus according to an alternative embodiment, with the detection means from Fig. 11;

Fig. 13 is a detail-form view of an administration apparatus with a detection means with a strain gauge;

Fig. 14 is a detail-form view of an administration apparatus according to an alternative embodiment, with the detection means from Fig. 13;

Fig. 15 is a detail view of an administration apparatus with a detection means with a snap disc; and

Fig. 16 is a detail view of an administration apparatus with a detection means with an electric switch.

DESCRIPTION OF PREFERRED EMBODIMENTS

Directional indications are used hereinafter as follows: the term "the distal direction" refers locally to that direction in which a specific component involved in the administration moves during the administration of the product, or to a local direction of flow of the fluids involved. In terms of absolute spatial directions, the distal direction may therefore vary depending on the position in the apparatus. The proximal direction is then the respective opposite direction. The term "distal end of the administration device as a whole" refers to that end to which the infusion set is connected and at which the product is ejected. Figures 1 to 4 are various views of a disposable cartridge 200 ("disposable module") of an administration apparatus. The cartridge has a housing 210 which is broken down into two cylindrical regions 211, 212 separated by a partition 214 (Fig. 2) . A proximal end region 213 connects the two regions 211, 212 and protrudes in part laterally beyond these cylindrical regions 211, 212. A product container 251 in the form of a glass carpule, which is closed at its distal end by a closure 253 and at its proximal end by a displaceable product piston 252, is accommodated in the first housing region 211. The closure 253 has a piercable septum which is held by a flanged cap on the distal end of the carpule body. The product container delimits a product reservoir 250 in which the product to be administered is received. The product is generally a medicament in fluid form, for example an insulin preparation, a hormone preparation, an anticoagulant, etc.

At its proximal end, the product container 250 rests against an annular container seal 255. At its distal end, the product container 250 is fixed in the axial direction by a screwed-on needle adapter 260 which presses the product container at its shoulder 254 in the proximal direction. The needle adapter 260 holds a hollow needle 261 which pierces the septum of the closure 253. Outwardly, the needle adapter 260 is configured as a male luer lock connection. A corresponding female mating part in the form of a luer connection 310 of an infusion set 300 is screwed into the male luer lock connection. This type of connection is standardized and allows any desired correspondingly standardized infusion set to be used.

A hydraulic reservoir 231, which is delimited proximally by a hydraulic piston 230, is formed in the second housing region 212. Laterally (in the circumferential direction) , the hydraulic reservoir is directly delimited by a cylindrical inner wall of the housing 210. In the distal direction (on the left-hand side in Fig. 2), the hydraulic reservoir is delimited partly by the end region 213 of the housing, and partly by a cover 240. A hydraulic channel 241, the cross section of which is sufficiently large in order not to significantly impede the flow of a hydraulic fluid located in the hydraulic reservoir 231 (an incompressible fluid, for example a suitable oil or dyed water) , is formed between the inner housing structures and the cover 240. The hydraulic channel 241 opens into an axial channel 242 formed in a housing region 215. This channel opens into a displacement reservoir 256 which is delimited in the axial direction on the one hand by the housing region 215, on the other hand by the product piston 252. In the circumferential direction (laterally) , the displacement reservoir 256 is delimited by that region of the glass carpule that is positioned proximally of the product piston 252. The volume of the displacement reservoir is dependent on the position of the product piston 252. In Fig. 2, before the administration begins, the displacement reservoir 256 has a very small volume.

The hydraulic piston 230 is connected to an advancing sleeve 232 rotatably but in an axially fixed manner. Over most of its length, the advancing sleeve 232 has an outer thread which is engaged with a comparatively short piston nut 220. The piston nut 220 is held stationarily in the housing 210. As will be described hereinafter in greater detail, the advancing sleeve 232 acts as a driven element for the drive means of a base unit.

A short channel 271, which extends outwards laterally, transversely to the direction of advancement of the hydraulic piston 230 and which may be seen particularly clearly in Fig. 4, branches off from the hydraulic reservoir 231, close to its distal end. The short channel opens into a receiving space into which a resilient element in the form of a membrane 272 made of a rubbery resilient material with an annular, peripherally reinforced edge is inserted. In this exemplary embodiment, the membrane 272 is arranged in such a way that it rests directly on the outer end of the channel 271 and as a result outwardly closes the channel. A transmission element in the form of a dimensionally stable, knob-like plunger 273 rests on the membrane 272. On the one hand, a guide element which is secured to the housing in the form of a fixing cap 274 holds the peripheral edge of the membrane 272 stationarily in the receiving space; on the other hand, the fixing cap guides the plunger 273 relative to the housing in such a way that the plunger can carry out a displacement merely within a predefined range, i.e. the fixing cap 274 delimits the path of displacement of the plunger 273. The membrane 272 is completely covered from the outside by the plunger 273 and the fixing cap 274 and as a result protected from soiling and damage. The channel 271, the membrane 272 and the plunger 273 jointly form a pressure sensing means 270, as will be described hereinafter in greater detail.

Figures 5 to 7 show a reusable base unit 100 ("reusable module") which is complementary to the disposable cartridge 200. The base unit 100 has a housing 110 which has a first partly cylindrical receiving region 111 for partly receiving the first housing region 211 of the cartridge and also a second, cylindrical receiving region 112 for receiving the second housing region 212 of the cartridge. Two parallel fixing pins 113, which serve to engage with complementary fixing openings 216 of the cartridge (Figures 1 and 3) , protrude from a stop face 115. A proximal end region 114 of the housing, accommodated in which is a detection means 400 (Fig. 7) which will be described hereinafter in greater detail and is connected to a control means 120 shown in this figure merely in a highly schematic manner via electrical lines 401, is likewise formed so as to protrude axially beyond the stop face.

The control means 120 comprises in particular a power source (for example an alkali battery or a rechargeable battery) , an electronic circuit for controlling the drive means which will be described hereinafter, a display (not shown; the display may for example be an LCD display or in the simplest case one or more light emitting diodes) connected to the electronic circuit, operating elements such as for example one or more keys (not shown; the keys may for example be film keys) , and also optionally acoustic and/or tactile output means, for example a loudspeaker, a buzzer and/or a vibration means. Control means of this type for medical administration apparatuses are known per se.

In addition, the base unit 100 comprises the aforementioned drive means 130 which is likewise shown only very schematically. The drive means comprises an electric motor (for example a stepper motor or a DC motor) , a gear mechanism for reducing the drive movement of the motor, and an entrainer 131 mounted on the output shaft of the gear mechanism. At least the gear mechanism is located in a finger-like region 116 of the housing, at the end of which the rotatable entrainer 131 (for example a wheel with entrainer ribs arranged on its circumference) is arranged. The housing is closed at its distal end by a cover 117.

In Figures 8 to 10, the base unit 100 and the cartridge 200 are shown in the assembled state. The cartridge is inserted into the base unit sufficiently far in the longitudinal direction that the proximal end region 213 of the cartridge 200 rests in its laterally overhanging region on the stop face 115 of the base unit 100. The finger-like region 116 protrudes into the advancing sleeve 232. The entrainer ribs of the entrainer 131 are engaged with corresponding longitudinal grooves on the inner side of the advancing sleeve 232 in order to transmit the rotary movement of the entrainer 131 to the advancing sleeve 232.

On account of the threaded engagement of the advancing sleeve 232 with the piston nut 220, the advancing sleeve 232 performs a helical movement in the distal direction when the entrainer 131 is made to rotate by the drive means 130. As a result, the hydraulic piston 230 is advanced in the distal direction. This produces a rise in pressure in the hydraulic reservoir 231, and the hydraulic fluid is displaced from the hydraulic reservoir 231 into the displacement reservoir 256 via the hydraulic channel 241. As a result, the product piston 252 is in turn advanced, so that the product is ejected through the hollow needle 261 into the catheter 320. Generally, such an ejection takes place in each case only for a few seconds at an interval of for example 20 minutes.

If the hollow needle 261 or the infusion set 300 is now occluded, or if the product piston 252 is stuck on account of excessive piston friction, the hydraulic fluid cannot evade the advancement of the hydraulic piston 230, and the pressure in the hydraulic reservoir rises markedly as the drive continues to act. As soon as a certain threshold pressure is exceeded, the membrane 272 bulges outwards in its central region and advances the plunger 273 outwards. As a result, the plunger actuates the detection means 400 which emits a corresponding signal to the control means 120. Suitable measures are thereupon taken in the control means, for example one or more of the following measures: incrementing an occlusion counter; outputting a warning or alarm signal; stopping the drive means; etc. In the embodiment of Figures 1 - 10, the arrangement of the membrane 272 directly on the end of the channel 271 causes a type of binary behaviour. Provided that the pressure in the hydraulic reservoir is lower than the threshold pressure, the membrane closes the end of the channel 271 and a force corresponding to the pressure multiplied by the cross-sectional area of the channel at its membrane-side end acts on the membrane. At the moment at which the threshold pressure is exceeded, this force is sufficient to bulge the membrane outwards. As a result, the hydraulic fluid now suddenly acts on the membrane over a very much larger area, namely in the entire bulged region of the membrane. As a result, the pressure-related force accordingly acting on the membrane is suddenly very much greater than beforehand, and as a result the membrane continues to bulge until the plunger 273 enters into abutment with the fixing cap 274 and thus assumes its end position. Only once the pressure in the hydraulic reservoir has dropped considerably again does the membrane 272 return on account of its resilience to its starting position and closes the channel 271 again.

While the detection means 400 is indicated in Figures 5 to 10 merely in a very highly schematic manner, Fig. 11 shows a specific exemplary embodiment of such a detection means. In this figure, the detection means is denoted in its entirety by reference numeral 410. This means comprises a piezoelectric element 412 (referred to hereinafter as the piezo element for short) which emits an electric signal when compressed. This piezo element 412 is held between a metal insert 411 and a fixing screw 413, the metal insert being held in an opening of the housing of the base unit. The metal insert 411 has a comparatively thin-walled deformable region 414 from which an annular wall 415 extends upwards. An inner thread, into which the fixing screw 413 is screwed sufficiently far that the piezo element 412 is securely held between the deformable region 414 and the fixing screw 413, is formed in an end of the annular wall 415 that is remote from the deformable region 414. The lines 401 for connecting the piezo element to the control means 120 are fed through a lateral opening.

If the plunger 273 is now advanced by the membrane 272 on account of an occlusion, it deforms the deformable region 414 of the metal insert and in this way generates a force acting on the piezo element 412 in the direction of advancement. This generates in the piezo element 412 an electric voltage (or to put it more generally an electric signal) which is received and evaluated by the control means 120.

It goes without saying that the piezo element can in this case also be mounted differently. In particular, the insert 411 does not have to consist of metal, but can for example also be made of a sufficiently resilient plastics material. Instead of the fixing screw 413, another type of fixing element can also be provided on the side of the piezo element 412 that is remote from the plunger 273, provided that this element can absorb a sufficient counterforce. The insert 411 does not in this case have to be directly connected to the fixing element; on the contrary, these parts can also be secured to the housing separately from each other. It goes without saying that the connection lines 401 can also be fed through in a different manner than shown in this figure.

Fig. 12 illustrates an alternative embodiment of the administration apparatus in which a piezo element is likewise used in the detection means. With respect to the detection means, reference is made to the foregoing description of Fig. 11. However, there are differences in the configuration of the pressure sensing means in the cartridge. In this embodiment, the membrane 272 has a thickened edge protruding on both sides beyond the actual membrane face. As a result, the membrane no longer rests directly on the end of the channel 271, but closes the receiving space set apart from the end of the channel 271. Instead of a membrane produced in one piece with the thickened edge, a membrane with a moulded-on annular holder can for example also be used, or the membrane can be arranged set apart from the end of the channel as a result of a suitable configuration of the receiving space, for example as a result of an annular bearing face for the membrane. The effective cross section, over which a pressure- related force acts on the membrane in the direction of displacement of the plunger 273, remains substantially unaltered during deformation of the membrane 272. That is to say, the normal area, which runs perpendicularly to the direction of displacement of the plunger 273 and is covered by the membrane, remains substantially unaltered even when the membrane arches. In the present exemplary embodiment, this area corresponds substantially to the cross-sectional area of the plunger 273.

This configuration allows the pressure in the hydraulic reservoir to be not only binarily detected, but continuously measured. During operation of the administration apparatus, the plunger 273 rests permanently against the detection means 410. In the event of a rise in pressure in the hydraulic reservoir, the force acting on the plunger 273 increases and can be measured by the detection means 410, in the present exemplary embodiment as a result of a rise of the piezoelectric signals generated in the piezo element.

The measured pressure-related force is substantially directly proportional to the pressure in the hydraulic reservoir.

This behaviour endures even when there are certain tolerances in the dimensions between the base unit 100 and the cartridge 200. In the example of Fig. 12, the cartridge precisely adjoins the base unit in the lateral direction. If there were instead a certain gap between the base unit and the cartridge, this would merely lead to the plunger 273 being advanced somewhat further in its direction of displacement, i.e. in the direction of the base unit 100, on account of the pressure in the hydraulic reservoir, and the membrane 272 would accordingly be somewhat arched. However, the force transmitted by the plunger 273 would remain substantially proportional to the pressure in the hydraulic reservoir. This force would be reduced merely by the resilient restoring force of the membrane that acts on the membrane as soon as the membrane has been deformed out of its planar shape. However, a suitable selection of the material and the dimensions of the membrane allows this force to be selected so as to be very low in relation to the pressure-related force. In the ideal case, the membrane is deformable in a force- free manner in this embodiment, and the pressure- related force acting on the plunger is constant and independent of the position of the plunger over its entire path of displacement up to the stop formed by the fixing element 274.

The greater the housing tolerances are, the more the position of the plunger 273 and thus the shape of the membrane 272 will fluctuate from cartridge to cartridge when the displacement apparatus is assembled. As hydraulic fluid inevitably flows through the channel 271 during displacement of the plunger 273 and the accompanying deformation of the membrane, a displacement of the plunger 273 inevitably also has repercussions on the pressure acting in the hydraulic reservoir. However, this effect can be kept low as a result of a suitable selection of the dimensions of the membrane and by minimizing the tolerances.

An alternative embodiment of a detection means 420 is illustrated in Figures 13 and 14. This embodiment also comprises an insert 421 which is basically constructed and arranged similarly to the insert 411 of the first embodiment. In particular, this insert also has a central deformable region. A strain gauge 422, which changes its electrical properties, in particular its electrical resistance, during deformation (bending, stretching, pulling, compressing and/or twisting) , is adhesively bonded onto this region. When the deformable region is deformed by the plunger 273 during an occlusion, then this deformation is transmitted to the strain gauge and as a result becomes measurable by the control means 120. In this embodiment too, the behaviour of the pressure sensing means in the cartridge may be binary as hereinbefore (Fig. 13) or the pressure may be continuously measurable (Fig. 14).

Fig. 15 illustrates a further embodiment of a detection means in which detection takes place binarily via a snap disc. A movable membrane 431 made of a resilient plastic is fitted in a housing opening of the base unit. In its central region, the membrane carries a deformation-resistant plunger 432. The deformation- resistant plunger acts during deformation of the membrane 431 on a snap disc 433 which is held on a printed circuit board 434. When the plunger 273 of the cartridge is now advanced during an occlusion, it deforms the membrane 431. This deformation is transmitted to the snap disc 433 via the plunger 432, as a result of which the snap disc snaps over and closes an electric contact. Suitable snap discs have long been known. This embodiment of the detection means is particularly suitable in conjunction with a binarily operating pressure sensing means of the cartridge, but can also be used with a continuously operating pressure sensing means.

Fig. 16 illustrates a further embodiment of a detection means in which the detection takes place binarily via a switch. Again, a membrane 441 with a plunger 442 is present. However, the membrane now acts not on a snap disc, but on a normal pushbutton switch 443 which is held on a printed circuit board 444 and which closes or opens a contact in a likewise purely binary or digital manner during corresponding deformation of the membrane 441. In this case too, use may be made of either a binarily operating cartridge or a cartridge with continuously operating pressure sensing. It goes without saying that a number of modifications are possible in all the aforementioned detection means. Thus, in this case too, the arrangement and assembly of the individual components can in particular also be readily changed without altering the basic mode of operation. Of course, detection means of a completely different type can also be used.

In all the foregoing exemplary embodiments, the base unit 100 and the cartridge 200 are telescoped in a longitudinal direction during assembly, whereas the plunger 273 moves in a direction lying transversely to the longitudinal direction. While this does not necessarily have to be the case, such a transmission of movement in the transverse direction is particularly advantageous because the relative position of the housing regions of the base unit and the cartridge in which the pressure monitoring means 270 and the detection means 400 are arranged is defined much more clearly with respect to the transverse direction than with respect to the longitudinal direction. Better precision, and thus higher reproducibility and reliability of the occlusion identification, is therefore achieved as a result of this arrangement. The precision is improved still further in that, in the region of the pressure monitoring means 270 and the detection means 400, the fixing pins 113 are present on the base unit and the openings 216 complementary thereto are present on the cartridge, the fixing pins and the openings causing in this region additional positional fixing in the transverse direction. An arrangement of this type is also advantageous when, for pressure detection, a plunger is guided on the housing in a directly sealing manner without a membrane being present.

The hydraulic-mechanical pressure monitoring described hereinbefore may advantageously be combined with a function monitoring by a measurement of motor parameters, in particular the motor current, in order to achieve redundancy. For this purpose, provision may be made to measure the motor current in the course of each administration cycle. If the motor current rises markedly in relation to earlier administration cycles or exceeds a certain absolute value, this likewise suggests an occlusion. The functional safety of the administration device can be further improved by monitoring both the pressure in the hydraulic reservoir and the motor current.

It will be clear from the foregoing discussion that the invention is in no way limited by the foregoing exemplary embodiments and a broad range of modifications are possible.

LIST OF REFERENCE NUMERALS

100 base unit

110 housing

111 first receiving region

112 second receiving region

113 fixing pin

114 proximal end region

115 stop face

116 finger-like structure

117 cover

120 control means

130 drive means

131 entrainer

200 cartridge (disposable)

210 housing

211 first region

212 second region

213 proximal end region

214 partition

215 housing region

216 fixing opening

220 piston nut

230 hydraulic piston

231 hydraulic reservoir

232 advancing sleeve

234 hollow space

240 cover

241 hydraulic channel

242 axial channel

250 product container

251 product reservoir

252 product piston

253 closure

254 shoulder

255 container seal

256 displacement reservoir

260 adapter

261 needle 270 pressure monitoring means

271 fluid channel

272 membrane

273 plunger

274 fixing cap

300 infusion set

310 connection

320 catheter

400 detection means

401 line

410 detection means

411 metal insert

412 piezo element

413 fixing screw

414 deformable region

415 annular wall

420 detection means

421 metal insert

422 strain gauge

Claims

PATENT CLAIMS

1. An administration apparatus for administering a liquid product, comprising:

- a reusable base unit (100) with a drive means (130) for generating a drive movement; and

- an exchangeable cartridge (200) which is detachably connectable to the base unit and comprises a housing (210) , a fluid reservoir (231) being arranged in or on the housing (210) and being configured to receive a fluid,

the cartridge comprising a driven element (232) which is configured to interact with the drive means (130) in order to transmit the drive movement from the base unit (100) to the cartridge (200) and to apply a pressure to the fluid reservoir (231) in order to eject the liquid product from the cartridge (200) ,

the cartridge comprising a deformable element (272) arranged to be in direct contact with the fluid in such a way that the pressure acting in the fluid reservoir (231) exerts a pressure-related force on the deformable element (272),

characterized in

that the cartridge further comprises a transmission element (273) which is movably connected to the housing (210) and is operatively connected to the deformable element (272) in such a way that the pressure-related force is substantially transmissible from the deformable element to the transmission element (273),

- and that the base unit (100) comprises a detection means (400; 410; 420; 430; 440) which is configured to detect the pressure-related force acting on the transmission element (273) of the cartridge (200) .

2. The administration apparatus according to Claim 1, wherein the base unit (100) and the cartridge (200) are configured so as to be slidable one inside the other in a longitudinal direction in order to connect the cartridge (200) to the base unit (100), and wherein the transmission element (273) is displaceable relative to the housing (210) substantially transversely to the longitudinal direction.

3. The administration apparatus according to Claim 2, wherein the base unit (100) has at least one fixing element (113) in a region adjacent to the detection means (400; 410; 420; 430; 440) and wherein the cartridge (200) has at least one fixing structure (216) which is complementary thereto in order to fix the base unit (100) and the cartridge (200) relative to each other with respect to a direction transverse to the longitudinal direction in the region of the detection means (400; 410; 420; 430; 440) .

4. The administration apparatus according to one of the preceding claims, wherein the deformable element (272) is a resilient membrane.

5. The administration apparatus according to one of the preceding claims, wherein the transmission element (273) is a plunger which is displaceably guided relative to the housing and is arranged in such a way that it is displaceable as a result of a deformation of the deformable element (272).

6. The administration apparatus according to one of the preceding claims, wherein the deformable element (272) is arranged on an inner side of a guide region (274) of the housing and wherein the transmission element (273) is arranged in an opening of the guide region (274) in such a way that it at least partly covers the deformable element (272) and that it is movable in the opening as a result of a change in configuration of the deformable element (272) in or counter to a direction pointing towards the outer side of the guide region (274) .

7. The administration apparatus according to one of the preceding claims, wherein the transmission element (273) is adapted to assume a range of positions in which the pressure-related force acting on the transmission element (273) is continuously dependent on the fluid pressure.

8. The administration apparatus according to one of the preceding claims, wherein the device has a channel (271) with a first and a second end, the first end of the channel opening into the fluid reservoir (231) and the second end of the channel opening into a receiving space which has a larger cross section than the channel and is at least partly delimited by the deformable element (272) .

9. The administration apparatus according to Claim 8,

- wherein the deformable element (272) has an area which is larger than the cross-sectional area of the channel (271) at its second end,

the deformable element (272) closing the channel (271) at its second end as long as the pressure in the fluid reservoir does not exceed a threshold pressure, and

the deformable element (272) being deformable as a result of the threshold pressure being exceeded, in such a way that the deformable element releases the second end of the channel, so that the pressure of the fluid acts on a region of the deformable element (272), the area of which is larger than the cross-sectional area of the channel (271) at its second end.

10. The administration apparatus according to one of the preceding claims, wherein the fluid reservoir

(231) is a hydraulic reservoir which is filled with a hydraulic fluid, the device further comprising a product container (250) for receiving the liquid product, and the product container (250) being arranged in such a way that the pressure can be transmitted from the hydraulic reservoir to the product container (250) in order to eject the liquid product from the product container (250) .

11. The administration apparatus according to one of the preceding claims, wherein the detection means (400; 410; 420; 430; 440) comprises at least one element (412; 422; 433; 443) having an electrical property which is variable continuously or in a plurality of steps as a result of the pressure-related force acting on the transmission element (273) , in particular one of the following elements: a piezoelectric sensor (412) or a strain gauge (422) .

12. The administration apparatus according to any of Claims 1-10, wherein the detection means (400; 410; 420; 430; 440) has at least one element (412; 422; 433; 443) having an electrical property which is binarily variable as a result of the pressure-related force acting on the transmission element (273) , in particular one of the following elements: a snap disc (433) or an electric switch (443) .

13. An administration apparatus for administering a liquid product, comprising:

a reusable base unit (100) with a drive means (130) for generating a drive movement; and

- a cartridge (200) which is detachably connectable to the base unit and has a housing (210) , with a fluid reservoir (231) arranged in or on the housing (210) for receiving a fluid and with a driven element (232) which is configured to interact with the drive means (130) in order to transmit the drive movement from the base unit (100) to the cartridge (200) and to apply a pressure to the fluid reservoir (231) in order to eject the liquid product from the cartridge (200) ,

the base unit (100) and the cartridge (200) being configured so as to be slidable one inside the other in a longitudinal direction in order to connect the cartridge (200) to the base unit (100),

- the cartridge comprising a movable transmission element (273) in the form of a displaceable plunger to which a pressure-related force is transmissible as a result of the pressure of the fluid in the fluid reservoir, and

the base unit (100) having a detection means (400; 410; 420; 430; 440) which is configured to detect the pressure-related force acting on the transmission element (273) ,

characterized in that the transmission element (273) is displaceable substantially transversely to the longitudinal direction.

14. The apparatus according to Claim 13, wherein the device has a channel (271) with a first and a second end, the first end of the channel opening into the fluid reservoir (231) and the second end of the channel opening into a receiving space having a larger cross section than the channel, and the transmission element (273) being arranged on the receiving space in such a way that the fluid located in the receiving space directly or indirectly exerts the pressure- related force on the transmission element (273) .