CLAMPING DEVICE FOR MEDICAL INSTRUMENT

Description

[0001] The invention relates to a device for pinching a flexible tube as well as a system for determining the presence or absence of a flexible tube, a method for detecting a flexible tube using such a pinching device and an apparatus comprising such a pinching device.

[0002] It applies to the medical field, and in particular to devices used for blood treatment, such as blood collection devices.

[0003] Blood collections are usually performed using a bag system that includes at least one donor blood collection bag connected via a flexible tube to a collection needle. During collection, the collection needle is inserted into a donor's vein. The collection bag contains an acid-citrate-dextrose (ACD) or citrate-phosphate-dextrose (CPD) anticoagulant to prevent blood clotting.

[0004] According to European standards, the volume of blood collected must be between 485 and 535 ml of blood, depending on the sex, height and weight of the donor.

[0005] There are automated blood collection devices available on the market. These devices typically include a shaker tray on which the blood collection bag rests and a device for clamping the flexible tube connecting the collection bag and the collection needle. The device is programmed to clamp the flexible tube when the required blood volume is reached in order to stop the collection.

[0006] For the proper functioning of these devices, it is important that the flexible tube to be clamped is present and correctly positioned in the clamping device.

[0007] WO 2016 / 084001 describes an example of an automated blood collection device. In this device, the pinching device for closing the flexible tube is configured to define three positions: an open position allowing the insertion of the flexible tube and its removal, a holding position, in which the flexible tube is held in the pinching device without closing it and a closed position, in which the pinching device is closed and compresses the flexible tube to stop the flow of blood. Furthermore, this pinching device may further comprise a flexible tube presence detector.

[0008] WO 2017 / 216343 describes a collection apparatus comprising a pinching device provided with a sensor. The sensor makes it possible to detect the degree of opening of the slot in which the tube is placed and thus to detect one of the three positions - open, holding or closed - of the pinching device.

[0009] Other medical devices are also provided with flexible tube pinching devices. For example, EP 3 290 065 describes an apparatus for extracting blood components comprising several pinching devices in which tube detectors, optical or mechanical, are arranged in the slot receiving the tube to be pinched.

[0010] In another example, document US 2019 / 0351138 describes a medical pump in which pressure sensors placed in the groove receiving the flexible tube make it possible to ensure that the flexible tube is mounted in the pump.

[0011] Also, document EP 3 103 489 describes a flexible tube pinching device for an extracorporeal circulator comprising three types of detectors: (i) a cover detector in the form of a photo-interrupter for determining the opening or closing of a cover, (ii) a tube presence detector in the form of a mechanical pressure sensor arranged in the slot receiving the flexible tube and (iii) a piston movement detector in the form of an optical sensor at the piston for determining an open position in which the flexible tube is not pinched and a closed position in which the flexible tube is pinched.

[0012] The invention provides a pinching device for differentiating between a position without a flexible tube and a position with a flexible tube in order to determine the presence or absence of a flexible tube in said device.

[0013] To this end and according to a first aspect, the invention proposes a device for pinching a flexible tube intended to determine the presence of said flexible tube in said pinching device, comprising: a support element comprising a support surface against which said flexible tube is intended to be pinched, a pinching element comprising a pinching surface facing the support surface, said pinching element being movable relative to said support element between at least one open position in which the flexible tube placed between the support surface and the pinching surface is not deformed, a closed position in which the flexible tube placed between the support surface and the pinching surface is closed and a closed position in which the support surface and the pinching surface are in contact, and a control unit configured to implement the following operations: actuate the pinching element from the open position towards the closed position until the pinching element is locked, detect the position of the pinching element thus locked,determine the presence or absence of the flexible tube based on the position of the detected pinching element.

[0014] According to a second aspect, the invention relates to a system for determining the presence or absence of a flexible tube in a pinching device comprising a pinching device according to the first aspect with said flexible tube.

[0015] According to a third aspect, the invention relates to a method for determining the presence or absence of a flexible tube in a pinching device according to the first aspect, said method comprising the following operations: moving the pinching element from the open position to the closed position, detecting the position of the pinching element thus moved, and determining the presence or absence of the tube based on the detected position of the pinching element.

[0016] A fourth aspect of the invention relates to an apparatus comprising a pinching device according to the first aspect of the invention.

[0017] Other items and benefits will appear during the following description.

[0018] The accompanying drawings illustrate the invention: [ Fig. 1 ] represents a schematic front view of a pinching device according to one embodiment in a wide opening position. [ Fig. 2 ] represents a partial schematic view of the pinching device of the Fig. 1 in a wide open position. Fig. 3 ] represents a partial schematic view of the pinching device of the Fig. 1 in a small opening position. [ Fig. 4 ] represents a partial schematic view of the pinching device of the Fig. 1 in a shutter position. [ Fig. 5 ] represents a partial schematic view of the pinching device of the Fig. 1 in a closed position. [ Fig. 6 ] represents a partial schematic and perspective view of the pinching device of the Fig. 1 . [ Fig. 7 ] represents a partial schematic and sectional view of the pinching device of the Fig. 1 . [ Fig. 8 ] represents a schematic top view of the support element of the pinching device of the Fig. 1 [ Fig. 9 ] represents a schematic and perspective view of a pinched flexible tube. [ Fig. 10 ] represents a schematic view of a pinching device according to another embodiment. [ Fig. 11 ] represents a schematic view of a medical device comprising a device for pinching the Fig. 1 . [ Fig. 12 ] represents a schematic view of a bag system that can be used with the device of the figure 11 .

[0019] There figure 1 represents a pinching device according to a first embodiment. This pinching device is intended to be part of a medical device, in particular a device for collecting blood from a donor or a patient. This pinching device 1 is intended to pinch a flexible tube 2 until a passage section of said flexible tube is closed and thus prevent the passage of a fluid through said section.

[0020] This pinching device includes: a support element 3 comprising a support surface 4 against which a flexible tube 2 is intended to be pinched, and a pinching element 5 comprising a pinching surface 6 facing the support surface 4, said pinching element 5 being movable relative to said support element 3 between at least one open position, a closed position and a closed position.

[0021] The term "open position" corresponds to the position in which the flexible tube placed between the bearing surface and the clamping surface of the clamping device is not deformed. In this position, shown in the figures 1 à 3 , the bearing surface 4 and the pinching surface 6 are spaced apart from each other by a distance greater than or equal to the outside diameter of the flexible tube to be pinched.

[0022] When the distance between the bearing surface 4 and the pinching surface 6 is greater than the outer diameter D of the flexible tube 2 ( figure 9 ), the opening position is called the "wide open position". This position, shown on the figures 1 et 2 , allows for example an operator to insert the flexible tube 2 into the pinching device 1, between the support surface 4 and the pinching surface 6.

[0023] When the distance between the bearing surface 4 and the pinching surface 6 is substantially equal to the outside diameter D of the flexible tube 2, the opening position will be called the “small opening position”. In this position, shown in the figure 3 , the flexible tube is held in place in the pinching device by a tight fit.

[0024] The term "closed position" corresponds to the position in which the flexible tube 2 placed between the bearing surface 4 and the pinching surface 6 of the pinching device 1 is closed. In this closed position, shown in the figure 4 , a passage section of the flexible tube 2 is closed, preventing the passage of a fluid through this section. The distance between the bearing surface 4 and the pinching surface 6 corresponds substantially to twice the thickness of the wall of the flexible tube. In connection with the figure 9 , the wall thickness of a flexible tube 2 corresponds to the difference between the outer diameter D of the flexible tube and the inner diameter d of said flexible tube.

[0025] The term "closed position" corresponds to the position in which the bearing surface 4 and the clamping surface 6 of the clamping device 1 are in contact. In this closed position, shown in the figure 5 , the flexible tube is missing from the pinching device.

[0026] For example, for a flexible tube having an internal diameter d of 3.5 mm and an external diameter D of 4.1 mm, the distance between the bearing surface 4 and the pinching surface 6 of the pinching device is substantially 6 mm in the large opening position, 4 mm in the small opening position, 1.2 mm in the closed position, and 0 mm in the closed position.

[0027] The pinching device 1 further comprises a drive member 7 arranged to produce a movement and transmit it to said pinching element 5. In a particular embodiment, the drive member 7 is configured to linearly move the pinching element 5. Alternatively, the pinching element is rotatable.

[0028] For example, the drive member is a linear motor, particularly a linear stepper motor. Alternatively, the drive member is a solenoid motor, a DC or AC motor, a brushless motor, or a pneumatic or hydraulic cylinder.

[0029] According to a particular embodiment shown on the figures 6 à 9 , the support element 3 comprises a first part 8 with a housing 9 for said flexible tube. The housing 9 is in the form of a recess comprising a substantially flat bottom 10 forming a support surface 4, and two side walls 11a, 11b parallel to each other extending from said bottom 10. The width of the housing corresponds substantially to the external diameter D of the flexible tube 2.

[0030] The first part 8 of the support element 3 further comprises an opening 12 for the movement of the pinching element described in more detail below. This opening 12 is in particular in the form of a slot. The opening 12 is isolated from said housing 9 by one of said side walls 11b of the housing 9. Thus, in the event of leakage of the fluid contained in the flexible tube 2 at the pinching device 1, the fluid flows into the housing 9 of the support element 3 but cannot pass inside the pinching device through the opening 12. The risk of the fluid flowing inside the pinching device 1 through the opening 12 provided for the pinching element 5 is therefore reduced.

[0031] Advantageously, the bottom 10 of the housing 9 has a slope, for example between 1 and 5 degrees, relative to the horizontal, in order to direct the fluid which can flow from the flexible tube towards the outside of the pinching device and / or towards the outside of the apparatus comprising said pinching device. For example, on the figure 11 , the bottom of the slope is on the side opposite the agitator tray 26 of the collection device 23.

[0032] According to the figure 8 , the housing 9 of said flexible tube further comprises a notch 13a, 13b on each of said side walls 11a, 11b allowing the flexible tube to be crushed by the pinching element.

[0033] Indeed, as illustrated on the figure 9 , when a flexible tube is crushed, the crushing zone 14 has a width L greater than the outside diameter D of the flexible tube.

[0034] According to a particular achievement and in connection with the figure 1 , the support element 3 further comprises a cover 15 intended to be mounted above the first part 8 of the pinching device 1. This cover 15 protects the pinching element 5 when it is mounted in the support element 3 in order to prevent an operator from hindering the movement of the pinching element during operation of the pinching device.

[0035] The support element 3 comprises a second part 16 secured to the first part 8 by means of two rigid rods 17a, 17b.

[0036] On the figure 1 , the drive member 7 of the pinching element 5 is fixed to the second part 16. The pinching element 5 is integral with the drive member 7. The pinching element 5 is arranged between the first and second parts 8, 16 of the support element 3.

[0037] The pinching element 5 is linearly movable through the opening 12 of the support element 3.

[0038] According to the figures 6 et 7 , the pinching element 5 comprises a body 18 in the form of a plate coupled at one end to the drive member 7 and comprising at the other end a curved portion ending in the pinching surface 6.

[0039] As illustrated in the figure 7 , the pinching element 5 has substantially the shape of a crook or the inverted letter J. This particular shape contributes to the sealing of the pinching device 1. Indeed, when the pinching element 5 moves, the pinching surface 6 moves towards the bearing surface 4 along an axis distinct from the axis in which the plate forming the body 18 moves. The opening 12 of the bearing element 3, through which the plate forming the body of the pinching element 5 moves, is isolated from the pinching surface 6 and from the bearing surface 4. In the event of leakage of a liquid contained in the flexible tube, the liquid cannot pass through the opening 12 of the bearing element and therefore does not penetrate inside the pinching device 1.

[0040] The pinching element 5 advantageously comprises a spring 19 arranged in the initial position, to place the pinching element 5 in the closed position. On the figure 7 , the spring is arranged in an opening of the plate forming the body 18 of the pinching element and comes into abutment against the first part 8 of the support element 3.

[0041] The drive member 7 is in particular a linear actuator with a stepper motor provided with an anti-rotation system as described in document US7969048.

[0042] As shown on the figures 1 à 5 , the pinching device 1 advantageously comprises a position detector 20 intended to determine the position of the pinching element 5, and in particular the closing position and the closing position.

[0043] This position detector 20 is remote from the support surface 4 and the clamping surface 6 of the clamping device 1, i.e. it is not at the level of the flexible tube 2 to be clamped. The position detector 20 indirectly detects the position of the clamping element 5 relative to the support element 3.

[0044] In particular, the position detector 20 is a sensor comprising a transmitter of a signal and a receiver of the transmitted signal. This sensor cooperates with the pinching element 5 to detect the position of said pinching element. This sensor is in particular a contactless sensor of the optical, inductive, capacitive, magnetic or ultrasonic type.

[0045] In a particular configuration, the position detector 20 comprises an optical sensor. The sensor is integral with the support element 3. As shown in the figure 1 , the sensor forming the position detector 20 is in particular fixed on a panel 21 secured to the second part 16 of the support element 3.

[0046] According to the figures 1 à 5 , the pinching element 5 comprises an opening 22 which cooperates with the sensor so as to allow reception by the receiver of the signal emitted by the transmitter when the pinching element is in one of the closed or closed positions and so as to prevent reception by the receiver of the signal emitted by the transmitter when the pinching element is in the other position.

[0047] For example, the signal is an optical signal of the light beam type. The transmitter and the receiver of the optical sensor are arranged on the same side of the plate 21 of the pinching element 5. In the closed position ( figure 5 ), the emitter and receiver of the optical sensor are opposite the solid part of the plate and the light emitted by the emitter is received by the receiver. In the shutter position ( figure 4 ), both the transmitter and receiver are facing the aperture, and the emitted light is received by the receiver.

[0048] In particular, the aperture is arranged to prevent the signal from being received by the receiver in the large aperture and small aperture positions.

[0049] Alternatively, the opening of the pinching element is arranged to partially allow reception of the signal by the receiver in the shutter position and to prevent reception of the signal in the open positions.

[0050] According to an embodiment variant shown in the figure 10 , the pinching device 1 is designed to determine the four positions of the pinching element 5, namely the large opening position, small opening position, closing position and closing position.

[0051] In this embodiment, the position detector 20 comprises a pair of sensors, which cooperate with at least one pair of openings 22 in the pinching element 5. This pair of sensors and openings makes it possible to determine the position of the pinching element using a truth table.

[0052] An example of a truth table is as follows, where 1 corresponds to light being transmitted to the optical sensor receiver and 0 corresponds to no light being transmitted to the optical sensor. [Table 1] Position Capteur 1 Capteur 2 Grande ouverture 1 0 Petite ouverture 0 0 Obturation 1 1 Fermeture 0 1

[0053] The pinching device 1 further comprises a control unit which controls the movement of the pinching element 5.

[0054] The control unit is in the form of an electronic and computer system which includes, for example, a microprocessor designed to execute a control program. The execution of this program allows the control unit to control, in particular, the pinching device, depending, for example, on the signals received by the position detector.

[0055] In this case and advantageously, in order to detect the presence or absence of a flexible tube 2 in the pinching device 1, the control unit is configured to: actuating the pinching element 5 from the open position towards the closed position until the pinching element 5 is locked, detecting the position of the pinching element thus locked, and determining the presence or absence of the flexible tube depending on the detected position of the pinching element.

[0056] The locking of the pinching element 5 occurs when the pinching element 5 is stopped in its movement, either by the presence of the flexible tube 2 crushed between the bearing surface 4 and the pinching surface 6, or by the bearing surface 4 directly.

[0057] In particular, the presence of a flexible tube 2 is determined if the position of the pinching element detected is the closure position ( figure 4 ). The absence of a tube is determined if the position of the pinching element 5 detected is the closing position ( figure 5 ).

[0058] The control unit is configured to react differently depending on the presence or absence of flexible tubing.

[0059] For example, if the flexible tube is missing from the pinching device, the control unit is configured to emit an audible and / or visual alert signal to the operator to alert him of the absence of the tube. In addition or alternatively, the control unit is configured to stop the apparatus comprising the pinching device.

[0060] If the flexible tube is present in the pinch device, the control unit is configured to continue operation of the device.

[0061] According to an advantageous embodiment, the control unit is further configured to check, prior to the flexible tube detection operations, for example when starting the device comprising the pinching device, that the different positions of the pinching element are correctly detected. This control operation makes it possible to ensure that during subsequent detections, failure cases do not induce incorrect reactions from the control unit.

[0062] For example, prior to the flexible tube detection operations and in the absence of a flexible tube in the pinching device, the control unit is configured to: actuate the pinching element 5 from the open position towards the closed position until the pinching element is locked detect the position of the pinching element 5 thus locked, determine the correct operation of the pinching device 1 as a function of the detected position of the pinching element 5.

[0063] If the detected pinch element position is the closed position, the device is working properly. If the detected pinch element position is not the closed position, the pinch device is defective. A warning signal can be issued to the operator.

[0064] The pinching device 1 described above with a flexible tube 2 forms a system for determining the presence or absence of a flexible tube in a pinching device.

[0065] A method is now described for detecting a flexible tube 2 in a pinching device 1, said method comprising the operations of: actuating the pinching element 5 from the open position towards the closed position until the pinching element 5 is locked, detecting the position of the pinching element 5 thus locked, determining the presence or absence of the flexible tube 2 as a function of the detected position of the pinching element 5.

[0066] The presence of a flexible tube is determined if the detected pinching element position is the closing position; the absence of a flexible tube is determined if the detected pinching element position is the closing position.

[0067] The pinching device as described above is generally included in an appliance.

[0068] Such a device is, in particular, a medical device which may be an infusion pump, a flexible tube welder, a device for clamping and welding flexible tubes or a blood treatment device. In a particular example, the device is a blood collection device.

[0069] Such a blood collection apparatus 23 is shown in the figure 11 and an example of a bag system for collecting blood is shown in the figure 12 .

[0070] The bag system comprises at least one collection bag 24 for collecting blood, said collection bag being connected to a collection needle 25 via a flexible tube 2. The collection bag 24 advantageously contains an anticoagulant solution. The collection needle is intended to be introduced into the vein of a donor in order to collect his blood in the collection bag.

[0071] A system for collecting a target volume of blood comprising on the one hand an apparatus for collecting a target volume of blood and on the other hand a bag system comprising a collection bag 24 and a sampling needle 25 connected to said collection bag by means of a flexible tube, is described below in more detail.

[0072] The apparatus for collecting a target volume of blood in a collection bag of a bag system further comprising a collection needle 25 connected to said collection bag via a flexible tube 2, comprises a tray 26 intended to receive the collection bag 24.

[0073] Advantageously, the apparatus further comprises a stirring device for moving the tray in order to stir the collection bag. Stirring the collection bag helps to mix the collected blood and the anticoagulant solution contained in the collection bag 24.

[0074] A particular method for collecting a target volume of blood in a collection bag 24 of a bag system further comprising a collection needle 25 connected to said collection bag via a flexible tube 2, comprises the following steps: determining the volume of blood collected in said collection bag 24, and partially pinching the flexible tube in order to reduce the flow rate of the collected blood, when the determined volume of blood collected in said collection bag 24 reaches a predetermined volume.

[0075] After the step of partially pinching the flexible tube, the method notably comprises the step of closing the flexible tube when the target volume of blood to be collected is reached in order to stop the collection of blood.

[0076] In particular to implement this method, the collection device comprises, in addition to the tray 26 intended to receive the collection bag, a device 1 for pinching a flexible tube as described above and essentially comprising: (a) a support element 3 having a support surface 4 against which said flexible tube 2 is intended to be pinched, (b) a pinching element 5 having a pinching surface 6 facing the support surface 4, said pinching element 5 being movable relative to said support element 3 between at least one open position in which the flexible tube placed between the support surface 4 and the pinching surface 6 is not deformed and a closed position in which the flexible tube placed between the support surface 4 and the pinching surface 6 is closed, and (c) a control unit configured to determine the volume of blood collected in said collection bag 24, and move the pinching element 5 from the open position to a first intermediate position between said open position and the closed position, when the determined volume of blood collected in said collection bag reaches a predetermined volume.

[0077] Moving the pinching element to a first intermediate position partially pinches the flexible tube, reducing the passage section of said flexible tube.

[0078] This partial pinching of the flexible tube has the effect of reducing the flow rate of blood collected. This reduction in flow rate at the end of the blood collection procedure allows the target volume of blood to be collected to be reached more accurately, without excessively extending the collection time since the reduction in flow rate is only implemented near the end of the collection procedure.

[0079] In particular, the predetermined volume of blood collected from which the flow rate is reduced is in the range of 90 to 99% of the target volume of blood to be collected, more particularly in the range of 95 to 99% of the target volume of blood to be collected. This predetermination is carried out by the control device before the start of fluid collection.

[0080] For example, for a target volume of 450 mL of fluid to be collected, the flow rate in the flexible tube is reduced when the volume of fluid collected reaches 440 mL.

[0081] The intermediate position is set by the control unit. It can be predetermined before blood collection, for example based on the target blood volume to be collected, or set during blood collection, for example based on the actual blood flow rate collected.

[0082] For example, the first intermediate position corresponds substantially to the middle position between the small aperture position and the shutter position.

[0083] Alternatively, the control unit is configured to, after moving the pinching element 5 to the first intermediate position, move the pinching element from the first intermediate position to a second intermediate position between said first intermediate position and the closure position, when the determined volume of blood collected in the collection bag reaches another predetermined volume of blood collection.

[0084] This operation further reduces the flow of blood collected as the target volume of blood to be collected approaches.

[0085] The movement of the clamping element into its various positions is implemented by the use of a drive member 7 in the form of a stepping motor, which, depending on the type of motor, allows a movement precision of the order of 0.013 mm.

[0086] In order to determine the volume of blood collected in the collection bag, the collection apparatus further comprises a device for measuring the volume of blood collected. In particular, this device is a weighing device associated with the tray for measuring the weight of the collection bag. The volume of blood collected in the collection bag is then deducted from the weight of the collection bag containing the collected blood.

[0087] When the collection device is put into operation, the control unit is configured to place the pinching element 1 in a wide open position in order to allow the operator to place the flexible tube 2 in said pinching device 1. The operator further places the collection bag 24 and the rest of the bag system on the plate 26.

[0088] The control unit is then configured to move the pinching element 5 from the wide open position to the closure position. When the flexible tube is closed, the operator inserts the needle into a vein of the donor.

[0089] Then, the drive unit is configured to move the pinching element from the closure position to the small opening position to enable the collection of blood from the donor by holding the flexible tube 2 in the pinching device 1.

[0090] Advantageously, just after the movement of the pinching element into a large opening position, the control unit is configured to implement the operations described above making it possible to determine the presence or absence of the flexible tube 2 in the pinching device 1. The movement of the pinching element 5 into a small opening position to allow blood collection is then only authorized if the flexible tube is present in the pinching device.

[0091] In this case, the pinching device further comprises a position detector 20 configured to detect the position of the pinching element 5, in particular the closing position and the closing position.

[0092] In the absence of a flexible tube, the control unit is configured to alert the operator of the absence of a tube. In the presence of the flexible tube, the control unit is configured to start the blood collection procedure, in particular by moving the pinching element 5 into the small opening position.

[0093] When the target volume of blood is collected in the collection bag 24, the control unit is configured to move the pinching element 5 from the small opening position to the closing position upon reaching the target volume of blood, in order to stop the collection of blood.

Claims

1. Device for clamping (1) a flexible tube (2) intended for determining the presence of said flexible tube (2) in said clamping device (1), comprising: - a bearing element (3) comprising a bearing surface (4) against which said flexible tube (2) is intended for being clamped, - a clamping element (5) comprising a clamping surface (6) facing the bearing surface (4), said clamping element (5) being able to move with respect to said bearing element (3) between at least one open position according to which the flexible tube placed between the bearing surface (4) and the clamping surface (6) is not deformed, an obturation position according to which the flexible tube placed between the bearing surface (4) and the clamping surface (6) is obstructed and characterised in that said clamping element also comprises a closed position according to which the bearing surface (4) and the clamping surface (6) are in contact, and also characterised in that the device for clamping (1) also comprises: - a control unit, said control unit being configured to implement the following operations: - actuating the clamping element (5) from the open position towards the closed position until the clamping element (5) is blocked, - detecting the position of the clamping element (5) thus blocked, - determining the presence or the absence of the flexible tube (2) according to the position of the clamping element (5) that has thus been detected.

2. Device according to claim 1, characterised in that the presence of the flexible tube (2) is determined if the position of the clamping element (5) detected is the obturation position, the absence of the flexible tube (2) being determined if the position of the clamping element (5) detected is the closed position.

3. Device according to one of claims 1 or 2, characterised in that the control unit is furthermore configured to emit an alert signal in case of absence of a flexible tube.

4. Device according to any of claims 1 to 3, characterised in that it further comprises a drive member (7) configured to linearly displace the clamping element (5).

5. Device according to claim 4, characterised in that the clamping element (5) comprises a body (18) in the form of a plate coupled at one end to the drive member (7) and comprising at the other end a curved portion ending with the clamping surface (6).

6. Device according to any of claims 1 to 5, characterised in that it further comprises a spring (19) arranged in the initial position to place the clamping element (5) in the closed position.

7. Device according to any of claims 1 to 6, characterised in that it further comprises a position detector (20) configured for detecting the position of the clamping element (5), the position detector (20) being a sensor comprising a signal transmitter and a signal receiver that cooperates with the clamping element (5) to detect the position of said clamping element.

8. Device according to claim 7, characterised in that the position detector (20) comprises an optical sensor.

9. Device according to one of claims 7 or 8, characterised in that the clamping element (5) comprises an opening (22) arranged so as to authorise the receiving by the receiver of the signal transmitted by the transmitter when the clamping element is in one of the obturation or closed positions, and in such a way as to prevent the receiver from receiving the signal transmitted by the transmitter when the clamping element is in the other position.

10. Device according to any of claims 7 to 9, characterised in that the position detector (20) comprises a pair of sensors.

11. System for determining the presence or the absence of a flexible tube (2) in a clamping device (1) comprising a clamping device (1) according to any of claims 1 to 10 with a flexible tube (2).

12. Method for determining the presence or the absence of a flexible tube (2) in a clamping device according to one of claims 1 to 10, said method comprising the following steps: - displacing the clamping element (5) from the open position to the closed position, - detecting the position of the clamping element (5) that has thus been displaced, - determining the presence or the absence of the flexible tube (2) according to the position of the clamping element (5) that has thus been detected.

13. Method according to claim 12, characterised in that the presence of a flexible tube (2) is determined if the position of the clamping element (5) detected is the obturation position, the absence of a flexible tube (2) being determined if the position of the clamping element (5) detected is the closed position.

14. Apparatus (23) comprising a clamping device (1) according to any of claims 1 to 10.

15. Apparatus (23) according to claim 14 intended for collecting blood, further comprising an agitator plate (26) intended for receiving a collecting bag (24)