LT5712B - Syringe piston seizing and tappet position setting and control system in the injecting infusion pumps - Google Patents

Abstract

The invention is related to medical devices. Describing injecting infusion pump with a new syringe seizing and piston positioning and control systems.

Description

TECHNICAL FIELD

The invention relates to medical devices, such as syringes for infusion pumps, and more particularly to a system for locating and controlling the syringe plunger and pusher.

TECHNICAL LEVEL

In modern syringes, the syringe plunger is automatically brought into and mechanically connected to the syringe plunger in an infusion pump for accurate dosing of the drug, allowing it to be delivered to the patient. This process is known as pinching the syringe plunger. The pusher drive control must ensure that the pusher is brought to the syringe plunger as quickly as possible, retard the pusher before touching the syringe so that it stops suddenly when the distance drops to the minimum required, and ensure complete delivery reliability, avoiding dangerous patient injection. The syringe plunger stop must be in continuous contact with the plunger, regardless of the pressure in the syringe, to prevent spontaneous drug flow (the so-called "siphon effect") should the pressure in the syringe become negative. The plunger gripping levers must be well connected to the plunger support, regardless of the diameter of the support and the syringe dimensions. The plunger plane must be fitted with a sensor that operates at a certain distance from the syringe plunger support, activating the plunger speed stop algorithm, and during the infusion, another sensor that controls whether the plunger support has moved away from the plunger. Finally, the sensors must be controlled so that the failure of either or both does not endanger the patient and is detected as soon as possible.

Once the plunger reaches the syringe barrel, the syringe plunger should be quickly and accurately positioned to determine the infusion time and inject the patient according to a programmed algorithm. Accurate positioning of the syringe pusher and control of the pusher movement are necessary to ensure that the drug delivery algorithm is executed, alerting service personnel to changes during the infusion process, and malfunctions that may occur due to unforeseen events. The control system is based on the positioning of the pusher relative to the bearing plane to which the syringe crimp is attached. All other dimensions for each syringe type and nominal volume used are pre-measured and stored in the pump memory. Therefore, it is sufficient to know the distance of the pusher from the plane of attachment of the syringe, and after inserting the syringe to enter (confirm) data on its nominal volume and type (brand), the controlling processor automatically determines the amount of drug in the syringe and other parameters. Continuous or periodic control of the pusher position is required to ensure that the pump reacts promptly to unexpected changes or malfunctions.

A known syringe clamping system is described in US5545140 and EP0514907, having two levers for angular movement parallel to the pusher plane and a small linear motion perpendicular to the pusher plane, as well as two perpendicular surfaces that engage the syringe plunger at a certain distance. and afterwards attracts him. There is a small sensor located between the levers for controlling the syringe plunger contact with the plunger, which consists of a button with a valve that opens the optical sensor when the button is pressed. This system is designed for pumps with a manual pusher drive when the operator performs self-propelling and lowering of levers.

The benefits of this system are its simplicity and functionality. Each element performs a defined function here. The levers continuously press the plunger nozzle against the pushing plane to ensure that the negative pressure in the syringe due to the difference in height between the pump and the patient will not release.

The disadvantages of this system are that the button here has to be very small in diameter to prevent it from being crushed without the syringe lever being pressed and creating a fake installed syringe condition. Such a button, when inserted with a very small syringe, may overlap the plunger nozzle and is therefore unsuitable for a pump with an automatic plunger drive where the process of piston nozzle clamping is not directly controlled by the operator. A single sensor button cannot be used for automatic pusher retrieval because there is no signal to trigger the retard rate reduction algorithm. In addition, it is not possible to provide continuous control of the pump operation with a single sensor button. Failure of the sensor to stop the pusher drive will endanger the patient's health.

Another very important aspect of the syringes in the infusion pumps is the pusher positioning and control system, which depends on constant and continuous monitoring of the amount of medication given to the patient. Several pusher positioning and control systems are known for use in infusion pumps. US6575936 describes a system having one or more sensors spaced at a certain distance within the stroke of the pusher to lock the intended positions of the pusher. A pusher is fitted with a valve that indicates a predetermined position when crossing the sensor flow. Then, knowing the dimensions of the individual syringe, the programmed speed is used to calculate the injection time of the medicine in the syringe and to set an agreed personnel alert time, and adding the amount of medicine already inputted to find out the total amount of medicine in the syringe. Further control of the pusher position can be performed by the stepper motor control pulses or the propeller rotation control sensor, depending on the controls provided with the pusher drive. One sensor and a valve of a certain length provide two positioning points within the stroke range, two sensors four respectively.

A positive feature of this system is its simplicity, which makes it quite common.

The disadvantage is that after the syringe is inserted, it will take a long time for the pusher to approach any sensor, which can take up to half the volume of the syringe. Another downside is the lack of continuous or at least periodic control of the pusher movement. Sensor failure during infusion may be long unnoticed or accepted as a useful signal. In addition, the small amount of medication in the syringe will not lock at all if the pusher is initially out of range of the sensor.

JP5042218 discloses the use of a two-track optical code ruler, one track for motion distance subdivision having transparent cells corresponding to a certain constant pitch, and the other track for positioning the pusher and having a length proportional to the sequence number. Positioning accuracy depends on the resolution of the reference track, that is, the number of slide cells per unit length of ruler.

A positive feature of this technique is that the position of the pusher is controlled throughout the stroke, independently of other controls, and there are no errors in linearity or wear.

System deficiencies include a limited resolution that depends on the position reference track resolution and the properties of the scan sensor. Complex high-resolution optical reference systems are prohibitively expensive and bulky and therefore do not use infusion pumps. If we consider the maximum number of transparent slides per unit length of resolution as a resolution, simple optical rulers with mechanical slits and widely used optical sensors can have up to two slits per millimeter. This would result in a positioning error of the pusher about 0.5 mm, which would be about 4% of the volume of the 3 ml syringe. This would be a relatively low accuracy in drug quantification.

Another drawback is the relatively large code length, proportional to the amount of medication in the syringe. When the syringe is inserted, the position of the pusher is determined only after the pusher has passed one code distance and part of the code within which it has been inserted. Thus, in the marginal case, a distance of almost two codes. If the pump is designed for syringes up to 60 ml, the stroke of the pusher must be at least 120 mm. At a resolution of 2 slices / mm, we would have 20 codes between 0.5mm and 10mm long. If the plunger is located at the end of code 20 after inserting the syringe, then code 19 will be recognized when the plunger is 19 mm apart or about 20% of the syringe volume. This can be a nuisance if it is important to quickly determine the infusion time, for example at high infusion rates. Another disadvantage of such a ruler is that when reading even codes, the sensor is closed and its failure at that time will remain undetected for quite some time.

THE SUBSTANCE OF THE INVENTION

The present invention provides a system for locating and controlling the syringe plunger and the plunger position, which provides complete reliability by automatically moving the plunger to the syringe, provides short and high precision plunger positioning, provides periodic control of the plunger position, and short distance when the sensor signal is not controlled.

In the syringe grab system, which consists of a syringe barrel clip, a syringe grab holder, a syringe plunger, two syringe plunger support grab levers, and a plunger closer to the plunger support strut, the plunger strut, the force vectors would always pass through the center of support, regardless of its diameter, and the sloping surfaces of the levers would continuously press the plunger support against the surface of the plunger, and, second, the lever clamps without the syringe would not cause the syringe to be in an incorrect condition.

There is a button in the pusher pusher plane between the syringe support grab levers to indicate the pusher is approaching the syringe support, interacting with two optical sensors and a shutter. The interaction of these elements enables detection of the piston rod approaching the pusher, triggering the slider feed rate deceleration algorithm, and controlling the constant contact of the syringe plunger rod with the pusher plane throughout the infusion.

During push-in positioning and control of the pusher, the system consists of a single-track code ruler with transparent boxes for optical signal scanning attached to the pusher drive housing and a code reading sensor mounted on a carriage firmly connected to the syringe pushers. The code recognition system consists of a raster disk and two scan sensors, which form a decoder for scanning raster disk signals and determining the direction of rotation. The sensor signals are processed by an electronic-software unit that calculates the position of the pusher relative to the reference plane to which the syringe crimp is attached, and then the amount of drug in the syringe and other required parameters.

The invention will now be described in more detail with reference to the drawings in which:

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Figure 1 is a general view of a syringe infusion pump of the present invention without a syringe inserted;

Fig. 2 is a general view of a syringe infusion pump of the present invention with a syringe inserted;

Figures 3a-3d are views of different stages of syringe plunger retention and locking mechanism;

Figures 4a-4c are views of a syringe support position indicating mechanism;

Figures 5 and 6 are general and schematic views of a pusher positioning and control system;

Figure 7 is a partial view of the codeword of the present invention.

DESCRIPTION OF THE INVENTION

In the syringe infusion pump shown in Fig. 1, the syringe plunger support clamping system comprises a syringe socket 1, a syringe barrel clamp 2, a syringe nipple holder 3, and a syringe plunger 4. piston support indicator button 8. Fig. 2 shows a syringe 9 inserted in the clamping system when the levers 6 and 7 are pressed against the support 11 of the piston 10.

As shown in Figs. 3a-3d, the piston levers 6 and 7 of the syringe plunger support 11 have only angular movement in one plane parallel to the pusher plane 5, the center of rotation Cj and C _{2 of} the levers 6 and 7 being symmetrical about the center of the syringe socket. . The levers 6 and 7 have sloping surfaces 12 and 13 which are inclined at an angle to the axis of symmetry of the pusher 4 with respect to the pusher plane 5.

By means of such a design, the pressed levers 6 and 7, as shown in Fig. 3b, compress the surfaces of the syringe plunger 11, the torque F _m of the levers 6, 7 generates a force F = F _m tga pressing the support 11 against the pushing plane. 5. Fig. 3c shows that any forming, parallel to the pusher plane 5, of the inclined surfaces 12 and 13 of the levers 6 and 7 is curved with a variable radius arc such that the vectors F _m j, F _m 2, F _m 3 are applied to the syringe plunger. would always pass through the center of support, regardless of its diameter D. For this condition to apply regardless of the height of the piston support 11, the upper edges 14 and the lower 15 of the sloping faces 12 and 13 form uniform curves of variable radius parallel to the pushing plane 5, only rotating about the axis of pivots 6 and 7 a variable radius and a tilted surface at varying angles. The lower edge 15 of said surface is raised at a certain distance from the pushing plane 5 so that the lever presses without the syringe do not fully depress the button 8 and do not create an incorrect condition of the installed syringe.

In the pushing plane 5, between the levers 6 and 7, is a button 8 of the proximity sensor of the pusher 4 to the syringe support 11, which, as shown in Fig. 4a, is connected to two optical sensors 16 and 17 and a damper 18.

As shown in Figures 4a-4c, the width of the damper 18 is less than the distance between the sensitive slots Pi and P ₂ of the optical sensors 16 and 17, resulting in three sensor signal states when the button 8 is pressed: in the initial position when the button 8 has no contact with the syringe. the piston support 11 or the non-pressed levers 6 and 7, the damper 18 has closed the sensor 16. Pressing the button 8 no more than halfway or closing the levers 6 and 7 without a syringe opens the sensitive slot Pi of the sensor 16 and in some Within the range of both sensors 16 and 17. Further pressing the button 8 (Fig. 4c), the valve 18 covers the sensitive slot P _{2 of the} sensor 17 and the pusher 4 approaches the syringe support 11 within the minimum distance that may be allowed during the infusion. The distance that the pusher 4 can travel from the first sensor 16 actuation to prevent an unintended infusion is determined during production and if the sensor 17 is covered within this distance, the grab levers 6 and 7 are lowered. Thus, the first optical sensor 16 is touched by the controller or pusher 4. button 8. The purpose of this sensor is to enable the slider 4 feed rate deceleration algorithm, which reduces the pusher 4 feed rate so that the pusher 4 can be stopped suddenly at any moment. The second optical sensor 17 controls that the syringe plunger support 11 has not moved away from the pusher plane 5 beyond what is permissible during the infusion. Button 8 has a large enough diameter so that it is still depressed when the syringe is inserted with its beveled plunger. Such a defect is provided by syringes with a nominal capacity of 1 ml, whose piston support 11 is very small in diameter and can deviate quite significantly from the axis of symmetry. The use of this syringe clamping system in manual push-pull pumps prevents operator error when the levers can be lowered without the needle clamping the syringe plunger and causing a malfunction of the installed syringe.

Ί

The button 8 and the two optical sensors 16 and 17 form a reliable control system that prevents uncontrolled infusion due to failure of any of the sensors 16, 17. In the absence of a fault, the logic sum of the signals of both sensors 16, 17 is always equal to one. If this logic sum is zero at the time of pushing the pusher 4, then the defective second sensor 17 or both sensors are defective at the same time, for example, their power supply has been interrupted. If this amount is zero during the infusion, then the first sensor 16 is defective or both sensors 16,17 are defective at the same time. If the first sensor 16 was actuated during pushing of the pusher 4, but the second sensor 17 did not switch off within the set distance, it means that it is defective in such a way that it continuously emits an actuation signal.

The system for locating and controlling the pusher in the syringe infusion pumps shown in Figs. 5-7 consists of a single track code ruler 19 mounted on a pusher drive housing 20, a code reading sensor 21 mounted on a carriage 22 having a helical drive nut 23 and firmly coupled to the syringe pushers 4. The code recognition system comprises a raster disk 24 mounted on a propeller 25 and two scan sensors 26 and 27 which form a decoder for scanning signals and rotating direction of raster disk 24. The signals of sensors 26 and 27 are processed by an electronic program unit 28 which calculates, by means of pre-entered pump mechanism calibration data and mechanical data of the syringes used, the instantaneous position of the pusher relative to the support plane to which the syringe is attached. the parameters you set.

As shown in FIG. 7, the code ruler 19 consists of uniform transparent windows 29 which provide a readable signal from the optical sensor 21. The minimum interval between cells 29 is selected such that the signals of adjacent cells 29 at the output of the scan sensor 21 are well separated from one another. The other intervals are longer than one another by one minimum size S, called a step whose length is well recognized by the scanning system. The smallest interval is called marker M, and it starts with all the codes. The next three intervals are called marks A, B, and C, one step S longer than marker M and one another. The optimal length of the marker M is two or three steps in 2S or 3S. The position of the pusher 4 is coded by four-character code combinations, hereafter referred to as K1, K2, K3 and so on. All marks begin with a transparent box 19 of the optical ruler and continue to the next box. All codes begin with a marker M followed by a three-character combination of sets A, B, C. If the marker length is set to 2S, then the character lengths will be: A = 3S, B = 4S, and C = 5S. the sign lengths will be: A = 4S, B = 5S, and O6S.

The codes are arranged to occupy the minimum length so that everyone is unique, and are arranged starting with the code with the shortest length so that the code elongation is not more than one step. At the end of the ruler, after the last code, a marker and a single transparent box are also formed to form the marker at the end of the last code, needed for reading ruler 19 in reverse. Codes of equal length form a group of codes within which they can be arranged anywhere. For shorter syringes to have a shorter position recognition interval, it is advisable to place the codes in ascending order from the end of the infusion. A variation of the ruler coding assuming a marker length of 3S and a pitch S of 0.25 mm is given in Table 1.

TABLE: LINING CODING EXAMPLE

Come on notation Come on meaning The length of the code Distance from Kl code marker to K (n + 1) code marker Of Steps, S mm Of Steps, S mm Cl COUNTRY 15th 3.75 15th 3.75 Q2 MAAB 16th 4.0 31st 7.75 Q3 MABA 16th 4.0 47 11.75 Q4 MBAA 16th 4.0 63 15.75 Q5 MAAC 17th 4.25 80 20.0 Q6 MABB 17th 4.25 97 24.25 Q7 MACA 17th 4.25 114 28.5 Q8 MBAB 17th 4.25 131 32.75 Q9 MBBA 17th 4.25 148 37.0 Q10 MCAA 17th 4.25 165 41.25 Kll MABC 18th 4.5 183 45.75 Q12 MACB 18th 4.5 201 50.25 Q13 MBAC 18th 4.5 219 54.75 Q14 MBBB 18th 4.5 237 59.25 Q15 MBCA 18th 4.5 255 63.75

Q16 MCAB 18th 4.5 273 68.25 Q17 MCBA 18th 4.5 291 72.75 Q18 MACC 19th 4.75 309 77.5 Q19 MBBC 19th 4.75 327 82.25 K20 MBCB 19th 4.75 345 87.0 K21 MCAC 19th 4.75 364 91.75 Q22 MCBB 19th 4.75 383 96.5 Q23 MCCA 19th 4.75 402 101.25 K24 MBCC 20th 5.0 421 106.25 K25 MCBC 20th 5.0 440 111.25 K26 MCCB 20th 5.0 459 116.25 Q27 MCCC 21st 5.25 478 121.5 K28 * M * 4 1.0 482 122.5

During the infusion, the codes are read in the reverse direction, i.e. from the end of the ruler 19. The code can only be recognized when the marker is recognized, so when reading in the reverse direction, the N code is assigned a marker that, when read in the direct direction, was part of the N + l code. The code length in the table corresponds to a step length of 0.25 mm and a marker interval of 0.75 mm. The maximum interval when the scan sensor 21 is illuminated is 5 steps or 1.25 mm. This is the distance over which scan sensor 21 failure may remain undetected. This distance is about 6.6 times smaller than the known two-track rulers.

The start of the coding ruler 19 should approximately coincide with the scan sensor 21 as the pusher 4 approaches as close as possible to the support plane 3 of the syringe crinkle while squeezing the medication.

Code Ruler 19 has a code recognition system consisting of a decoder consisting of an optical raster disk 24 and two sensors 26 and 27. One of them, for example 26, is for scanning raster disk intervals. The raster disk 24 is firmly coupled to the auger screw 25 and has a number of angular intervals over a distance that is a multiple of the number of steps of the ruler 19. In this way, the raster disk 24 forms a synchronous system relative to the code ruler, which divides the 19-digit intervals of the code ruler into a number of raster disk intervals. Based on how many raster disk intervals fit into a single code ruler interval and sets the value for each character. Marks of equal length may have different number of raster disk intervals due to mechanical errors and optical properties. In order for the optical ruler step count to be reliable and for a raster disk to have a single interval error, one or more optical ruler steps must match three or more raster intervals. Then, the error of one raster disk interval in determining the length of the ruler interval will not yet equalize two intervals that differ in one step, and will not produce a recognition error. Thus, the raster disk 24 must have at least three intervals relative to the ruler 19 per step of the ruler 19. Marker M will then match 9 + 1, mark A-12 + 1, B -15 ± 1, and C-18 ± 1 raster disk intervals. The known composition and position of the ruler codes also determines the position of the pusher 4 away from the agreed location of the syringe, for example, the syringe crimp support plane 3. The positioning error of the pusher 4 is not more than one raster disk interval or 1/3 . For the synchronous system to function reliably, it is essential that the cumulative error of the ruler and propeller pitch does not differ by more than 1/3 of the ruler pitch throughout the stroke.

The second sensor 27 of raster disk 24 is shifted relative to the first by 1/4 of the raster spacing period, thereby causing its signal to lag or outperform the first sensor signal by 1/4 period, depending on which direction the rotating disk 24. Compares the two sensor signals according to known algorithm and determines the direction of raster rotation and thus the pusher movement. This is because the screw 25 may be rotated in the reverse direction for a short time during the infusion, for example in the event of an unauthorized pressure increase in the syringe (occlusion), in which case the screw should be rotated in reverse to reduce the pressure. also be accurately captured and evaluated for code value and pusher 4 position.

With a higher number of raster blades 24 per step 19 of the ruler, the scanning system can also be asynchronous, where the number of raster intervals is not a multiple of the number of ruler steps, and vice versa, the number of raster steps overlap. In both cases, it is important to evaluate the probability of error and the accuracy of the positioning of the pusher.

The raster disk can also be mounted on the motor axis provided that the motor is synchronously connected to a propeller, such as a gear or pinion gear reducer. If the motor or gear unit is equipped with a directional decoder, it may be used in place of the raster disk, provided that its resolution meets the above requirements. In addition to being optical, the ruler and raster disk may also be shaped in a manner that provides static scanning of the signal, such as magnetic recording and a magnetic flux sensitive sensor.

The electronic-software unit 28 is a portion of the overall pump control electronics that performs the described sensor control and control steps.

Claims (2)

DEFINITION OF INVENTION 1. Syringe plunger and plunger positioning and control system for syringes in infusion pumps, wherein the syringe plunger system includes syringe body attachments in the infusion pump and syringe plunger with plunger plunger plunger plunger plunger and plunger plunger the positioning system is mounted inside the pump housing and consists of a push rod positioning code ruler and a code reading and recognition decoder, characterized in that the syringe clamping system consists of: a) syringe plunger supports (11) for engaging gripping levers (6, 7) spaced from the surface (5) of the plunger (4), each having a single sloping surface (12,13) in contact with the syringe plunger support (11). and a tilting pusher (4) axis of symmetry, such that the arms (6, 7) rotating about a center (Ci, C2) torque is developed force (F _m) creates a force (F) urging the syringe support (11) at a push surface ( 5), furthermore, any of the forming surfaces (12, 13) of the levers (6, 7), which are parallel to the pushing plane (5), are bent by a variable radius arc such that the pressing force (F _m ) always coincides with the syringe plunger support ( 11) diameter (D) regardless of diameter (D) size; b) a sensor button (8) for approaching the pushing surface (5) to the syringe plunger support (11), the diameter being set so that it is larger than the distance between the clamped levers (6, 7) so that the syringe plunger support (11) and when the said support (11) is inclined at its maximum with respect to the axis of symmetry of the pusher (4) or when the levers (6, 7) engage without a syringe; (c) syringe-grab control systems consisting of an interconnected button (8), two sensors (16,17) and a valve (18), wherein: 1) the first sensor (16) is covered with the syringe plunger support (11) in contact with the button (8) and the second sensor (17) is exposed; ii) Both sensors (16,17) are open with the syringe plunger support (11) depressed! the button (8) about halfway through it or when the levers (6, 7) are pressed together without the syringe plunger support (11); iii) the first sensor (16) is exposed and the second sensor (17) is closed when the syringe plunger support (11) is pressed with levers (6, 7) against the surface (5) of the plunger (4) and the detection and control system shall consist of: d) optical coding rulers (19) consisting of codes (K1, K2, K3, etc.) composed in turn of characters optionally of (M, A, B or C), where each character (M, A, B) , C) corresponds to an interval of a certain length, which begins with a transparent optical ruler window (29) and extends to the next window (29) where the next sign begins, the characters (M, A, B, C) being one after the other by one minimum size , called a step (S) consisting of 1/2 or 1/3 of the minimum length of a character called a marker (M), it starts with all the codes (Kl, K2, K3, etc.), the other three characters in the code can be any character ( A, B, or C) and are designed so that all codes (Kl, K2, K3, etc.) are unique; e) an optical coding ruler (19) for scanning and recognizing code readings from a read sensor (21) mounted on a carriage (22) which is rigidly connected to the pusher housing (4) and incorporates a screw drive nut (3). a disk (24) attached to the drive screw (25) of the pusher (4) having three or more increments corresponding to one step of the optical ruler (19) and two raster signal reading sensors (26, 27) rotated relative to one another. 1/4 of the raster period and forming a decoder for the direction of rotation of the propeller (25); f) an electronic-software unit (28) controlling the infusion pump based on the sensor signals of the syringe clamping system and the optical bar code reading and recognition system. 2. A system as claimed in claim 1, characterized in that the lower edges (15) of the levers (6, 7) are raised from the surface (5) of the pusher (4) so that the levers (6, 7) press the button (8) without collapsing. about half its stroke and so that the first sensor (16) is triggered but the second sensor (17) is not covered (off).