Gas cushion injection system and method for retinal vein injection procedures

Abstract

The application belongs to the technical field of ophthalmic robots, and provides a gas buffer injection system for retinal vein injection surgery, which comprises a flowmeter, a tee A, a gas pressure sensor, a sample injector and a micro linear servo driver, three interfaces of the tee A are connected with the flowmeter, the gas pressure sensor and the sample injector respectively, the sample injector is connected with the micro linear servo driver, the rear end of the micro linear servo driver is provided with a pressure sensor, the pressure sensor is used for measuring the pressure of the top gas in the tee A, and the gas is below a viscous liquid. A gas buffer injection method is also provided, according to the optimal injection volume curve and the feedback data of the gas pressure sensor, the movement distance of the push rod of the micro linear servo driver is adjusted in real time, and injection is carried out according to the optimal injection volume curve. The application adds gas in the pipeline, uses the gas to buffer the injection pressure, takes the gas pressure as the feedback data, adjusts the injection speed, and realizes smooth drug injection.

Description

Technical Field

[0001] This invention belongs to the field of ophthalmic robotics technology, and specifically relates to a gas-buffered injection system and method for retinal intravenous injection surgery. Background Technology

[0002] Retinal vein occlusion (RVO) is a leading cause of vision loss in older adults worldwide. It is characterized by the formation of blood clots in the central or branch vessels of the retinal veins, leading to severe vision loss or even blindness. Due to the complexity, precision, and importance of the retina's anatomy and function, retinal surgery is considered a highly challenging and difficult surgical procedure. Currently, there is no clinically effective treatment. In recent years, retinal vein injection (RVC) has been proposed as an innovative method. Surgeons inject thrombolytic drugs into the blocked retinal veins to dissolve the blood clots, which is expected to restore blood circulation in the retinal veins.

[0003] However, in RVC (Retinal Vascular Ventilation) techniques during retinal microinjection surgery, a microinjector is typically connected to the viscous fluid control unit of a vitrectomy machine, using a fixed pressure for drug injection, or controlled by a doctor via a foot pedal. For example, Chinese utility model patent CN203341901U discloses a multifunctional ophthalmic microinjector. Chinese invention patent CN107096101A discloses an injection method using a servo-controlled needleless injector. In these cases, the injection of drug fluid into the subretinal or retinal blood vessels is uncontrollable, causing significant impact on retinal tissues, and lacks real-time and effective feedback mechanisms. This introduces additional risks to the injection process. Therefore, there is an urgent need for an injection device based on pressure feedback and flow detection, and through the design of related control methods, to ensure a stable flow rate and minimal impact during intraretinal vascular injection. Summary of the Invention

[0004] This invention addresses the technical problems existing in the prior art by providing a gas-buffered injection system and method for retinal vein injection surgery. Gas is added to the tubing to buffer the injection pressure, and the gas pressure is used as feedback data to adjust the injection speed, thereby achieving stable drug injection.

[0005] The technical solution adopted in this invention is: a gas buffer injection system for retinal vein injection surgery, including a flow meter, a three-way connector A, a pressure sensor, a sample injector, and a miniature linear servo driver. The three ports of the three-way connector A are respectively connected to the flow meter, the pressure sensor, and the sample injector. The sample injector is connected to the miniature linear servo driver. The pressure sensor is used to measure the pressure of the gas at the top of the three-way connector A, and the gas is below a viscous liquid.

[0006] Furthermore, both the push rod of the micro linear servo driver and the handle of the injector are provided with threaded holes and connected by screws.

[0007] Furthermore, both the injector and the miniature linear servo driver are fixed to the base.

[0008] Furthermore, the rear part of the injector is located inside the base, and a cover A is fixed on the base. The cover A has a groove that matches the flange edge in the middle of the injector, and the flange edge is embedded in the groove.

[0009] Furthermore, the miniature linear servo driver is located inside the base, and a cover B is fixed on the base. The cover B has a fixing groove that matches the bearing of the pressure sensor at the rear end of the miniature linear servo driver, and the bearing is located inside the fixing groove.

[0010] Furthermore, a three-way valve B is provided between the three-way valve A and the injector, and the three ports of the three-way valve B are respectively connected to the three-way valve A, the injector, and the supplemental viscous liquid syringe.

[0011] Furthermore, the flow meter has a full-scale flow rate of 1 ml / min and an accuracy of 5%; the injector has a specification of 1 ml and a scale range of 30 mm.

[0012] The technical solution adopted in this invention is: a gas-buffered injection method for retinal vein injection surgery, comprising the following steps:

[0013] Step 1: Assemble the above-mentioned gas-buffered injection system for retinal vein injection surgery. Connect the syringe device to the outlet end of the flow meter. The flow meter, pressure sensor and miniature linear servo driver are all connected to the control device. The top of the three-way valve A is filled with gas, and the rest of the gas-buffered injection system for retinal vein injection surgery is filled with viscous liquid.

[0014] Step 2: The control device sets the starting speed of the miniature linear servo drive push rod movement according to the optimal injection volume curve and flow rate limit value required by the injection target;

[0015] Step 3: Insert the micro-needle at the end of the syringe device into the experimental subject;

[0016] Step 4: Turn on the start switch of the miniature linear servo driver. The controller device adjusts the push rod movement distance of the miniature linear servo driver in real time according to the optimal injection volume curve and the feedback data of the air pressure sensor, and performs injection according to the optimal injection volume curve.

[0017] Furthermore, in step 4,

[0018]

[0019] Where y is the distance the push rod travels, R is the radius of the push rod, V is the volume of the viscous liquid, P0 is the initial air pressure, P1 is the current air pressure, and V0 is the initial air volume; P0 and P1 are measured by the air pressure sensor; V is obtained from the optimal injection volume curve.

[0020] Furthermore, in step 4, the controller receives feedback data from the pressure sensor, calculates the injection pressure, and the injection pressure must not exceed the injection pressure limit value; otherwise, the push rod movement speed of the micro linear servo drive is immediately reduced. The controller also receives feedback data from the flow meter, outputs the true volume curve based on the conversion relationship between flow rate and volume, and compares it with the optimal injection volume curve.

[0021] Compared with the prior art, the beneficial effects of this invention are:

[0022] 1. The injection system provided by this invention has a gas buffer function, enabling stable, constant-speed, or stable-variable-speed drug injection during fundus injection and retinal vein injection. Furthermore, real-time pressure and flow feedback allows for more effective real-time control of the injected drug.

[0023] 2. The injection method provided by this invention can perform gas-buffered injection in real time based on a set optimal injection volume curve through feedback. This improves upon the shortcomings of purely hydraulically driven injection, which suffers from high inertia and is prone to instability during the injection process. Furthermore, it overcomes the deficiencies of purely pneumatically driven injection, such as insufficient power, long injection time, and a high risk of injection failure. By combining the advantages of both methods, the injection process effectively reduces the impact of the drug fluid on the retinal tissue. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the injection system according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the sampler according to an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of the cap A according to an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the structure of the cap B according to an embodiment of the present invention;

[0028] Figure 5 This is a flowchart of the injection method according to an embodiment of the present invention;

[0029] Figure 6 This is a gas-buffered injection model diagram of the injection method according to an embodiment of the present invention;

[0030] Figure 7This is a flow-time curve obtained by a flow meter in the injection method of this invention embodiment;

[0031] Figure 8 This is a volume-time curve of the injection method according to an embodiment of the present invention.

[0032] In the diagram: 100, flow meter; 200, pressure sensor; 300, viscous liquid injector; 400, injector; 410, flange; 500, cap A; 510, slot; 600, base; 700, miniature linear servo driver; 800, cap B; 810, fixing slot; 900, tee A; 1000, tee B. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Embodiments of the present invention provide a gas-buffered injection system for retinal vein injection surgery, such as... Figures 1-4 As shown, it includes a flow meter 100, a tee A900, a tee B1000, a pressure sensor 200, an injector 400, and a miniature linear servo driver 700. The flow meter 100, tee A900, tee B1000, and injector 400 are connected sequentially. The top interface of tee A900 is connected to the pressure sensor 200 via an adapter tube. The pressure sensor measures the pressure of the gas at the top of tee A900. The top interface of tee B1000 is connected to a replenishing viscous liquid injector 300, which contains viscous liquid and serves to replenish it. The flow meter 100, tee A900, tee B1000, injector 400, and replenishing viscous liquid injector 300 constitute the conduit for the flow of the viscous liquid. In use, the top of tee A900 is filled with gas, and the rest of the conduit is filled with viscous liquid. The injector 400 is used to propel the flow of the viscous liquid. In this embodiment, the viscous liquid is silicone oil and the gas is air.

[0035] The miniature linear servo actuator 700 is a miniature servo electric actuator that integrates a micro motor, reducer, lead screw structure, sensor, and drive control system. The actuator 700 can achieve precise servo control at any position within its stroke range and can push the handle of the injector 400 according to a predetermined trajectory. Furthermore, a pressure sensor is located at its rear end to measure the pressure applied to the actuator. The miniature linear servo actuator 700 is connected to the injector 400; specifically, both the actuator 700 and the handle of the injector 400 have threaded holes and are connected by a screw.

[0036] Both the injector 400 and the miniature linear servo actuator 700 are fixed to the base 600. The base 600 ensures that the center points of the push rod of the miniature linear servo actuator 700 and the handle of the injector 400 are on the same horizontal line. The rear part of the injector 400 is located inside the base 600, and the base 600 fixes the injector 400 to the base 600 via a cover A500. The cover A500 has a slot 510 that matches the flange edge 410 in the middle of the injector 400, and the flange edge 410 is inserted into the slot 510. The cover A500 has four M3 threaded holes and is fixed to the base 600 by bolts. The miniature linear servo actuator 700 is located inside the base 600, and the base 600 fixes the miniature linear servo actuator 700 to the base via a cover B800. The cover B800 has a mounting groove 810 that matches the bearing of the pressure sensor at the rear end of the miniature linear servo driver 700. The bearing is located within the two semi-circular mounting grooves 810. The cover B800 has two M3 threaded holes for fixing to the base 600 with bolts.

[0037] In this embodiment, the full-scale flow rate of the flow meter 100 is 1 ml / min, and the accuracy is 5%. The three-way valves A900 and B1000 are common medical-grade three-way valves. The syringe 400 has a capacity of 1 ml and a scale range of 30 mm. The total range of the push rod of the miniature linear servo driver 700 is 30 mm.

[0038] Embodiments of the present invention also provide a gas-buffered injection method for retinal vein injection surgery, such as... Figure 5 As shown, it includes the following steps:

[0039] Step 1: Assemble the above-mentioned gas buffer injection system for retinal vein injection surgery. The outlet end of the flow meter 100 is connected to the syringe device. The flow meter 100, the pressure sensor 200 and the miniature linear servo driver 700 (including the drive control system and pressure sensor) are all connected to the control device.

[0040] Fill the tubing of the gas-buffered injection system with gas and silicone oil: The top of the A900 tee is filled with clean air, the initial volume of which is known; all three ports of the A900 and B1000 tee are turned on; the viscous liquid injector 300 fills the tubing with silicone oil from the top through the B1000 tee and then seals it (closing the A900 port); the top port of the B1000 is turned off. The syringe device contains the medication to be injected.

[0041] Step 2: The control device sets the starting speed of the micro linear servo drive 700 push rod movement based on the optimal injection volume curve and flow rate limit value required by the injection target. The optimal injection volume curve is the relationship curve between drug liquid volume and time.

[0042] Step 3: Insert the micro-needle at the end of the syringe device into the predetermined position and depth on the test subject at a preset angle. Open all interfaces of the A900 three-way connector.

[0043] Step 4: Turn on the start switch of the micro linear servo driver 700. The controller device adjusts the push rod movement distance of the micro linear servo driver 700 in real time according to the optimal injection volume curve and the feedback data of the air pressure sensor 200, and performs injection according to the optimal injection volume curve.

[0044] To illustrate the push rod control principle in more detail, consider the following example: Within the flow rate range of 10 μl / min to 200 μl / min set for the experiment, select a value, here assumed to be 183 μl / min. Based on the accuracy of the micro linear servo driver and the specifications of the injection needle, it can be calculated that the linear servo driver can advance 1.83 μl per step. Therefore, to achieve the required flow rate, the stepping command time is set to 100 steps / min, thus producing an instantaneous flow rate of 183 μl / min.

[0045] Based on the above correspondence, a tracking volume curve can be designed specifically for the tip of a micro-injection needle based on the relationship between flow rate and propelled fluid volume. The relationship is as follows:

[0046] V=∫Qdt=πr 2 x

[0047] In the above formula, V is the volume of drug liquid injected, Q is the flow rate, t is the time, r is the radius of the micro-injection needle, and x is the distance the solution travels in the micro-injection needle.

[0048] The first equation above represents the conversion relationship between volume and flow rate described in step 4. From the above equation, we can see that the injection volume of the drug liquid is in a first-order differential relationship with the flow rate; when the radius of the micro-injection needle remains unchanged, the injection volume of the drug liquid is directly proportional to the distance the solution moves in the micro-injection needle.

[0049] Based on the above relationships, different ophthalmic surgeries require different drug volumes, and there are also limitations on the injection flow rate (or velocity). Therefore, based on these two requirements, an optimal injection volume curve can be designed to obtain a control curve that can be used to track the solution position of the injection needle. The movement position or speed of the push rod of the micro linear servo driver 700 can then be controlled and tracked by a control device.

[0050] The following is the control algorithm: Figure 6 The model shown yields:

[0051] P0V0=P1V1

[0052] ΔV=V0-V1

[0053] πR 2 y = πr 2 x+ΔV

[0054] From the above three equations, we can obtain:

[0055]

[0056] Where y is the push distance of the push rod, R is the radius of the push rod, P0 is the initial air pressure, P1 is the current air pressure, V0 is the initial air volume, and V1 is the current air volume; P0 and P1 are measured by the air pressure sensor 200.

[0057] x can be obtained through a pre-designed optimal injection volume curve, because the solution movement distance of the micro-injection needle satisfies the relationship between the drug liquid injection volume and the solution movement distance. Therefore, the equation for the distance the push rod travels can be transformed into:

[0058]

[0059] Assuming the optimal injection volume curve is The first quarter curve is calculated in real time based on the real-time feedback of P1 and the value of V, and the position of y is input through the push rod. This can keep V output according to the predetermined curve required for ophthalmic surgery, or it can make V increase constantly and output smoothly, and the impact force is not as large as that of a pure liquid pump.

[0060] Ophthalmic surgery has certain limitations on the injection flow rate and injection pressure. Therefore, the flow meter and the pressure sensor at the rear end of the push rod can be used to detect the flow rate and injection pressure.

[0061] The flow meter has an error of 2 μl / min within the range of 0 μl / min to 40 μl / min, and an error of 0.05% during flow measurement processes above 40 μl / min. Both error ranges are within the test requirements. The flow-time curve measured by the flow meter is shown below. Figure 7 As shown, after integration, the actual volume-time curve is obtained, as shown in the figure. Figure 8 As shown, its accuracy can be verified by comparing it with the designed optimal injection volume curve. Figure 8 The volume-time curve shown is very close to The first quarter of the curve's cycle.

[0062] Once the bearing at the rear end of the miniature linear servo actuator is fixed, the force acting on the push rod, i.e., the force propelling the piston, can be measured. The injection pressure at the injection needle can then be calculated using Bernoulli's equation. The specific calculation process is as follows:

[0063] Assuming an ideal situation, the liquid in the syringe and the liquid in the injection needle satisfy Bernoulli's equation:

[0064]

[0065] In the above formula, p1 and p2 are the pressure of the fluid per unit volume in the injector and the pressure of the fluid per unit volume in the injection needle, respectively; ρ1 and ρ2 are the density of the silicone oil solution and the density of the drug solution, respectively; v1 and v2 are the flow rates of the silicone oil solution in the injector and the drug solution in the injection needle, respectively; h1 and h2 are the heights of the center of the injection needle tube and the center of the injection needle above the ground, respectively; c is a constant; and g is the standard gravitational acceleration.

[0066] v1 can be directly obtained by the host computer of the micro linear servo driver, v2 is calculated from the flow rate Q measured by the flow meter according to v2=∫Qdt, and ρ1, ρ2, h1, h2, and c are known quantities.

[0067] Where p1 can be obtained from the following formula.

[0068]

[0069] In the above formula, F is the feedback force measured by the pressure sensor of the miniature linear servo driver.

[0070] Based on the above analysis, the value of p2 can be derived:

[0071]

[0072] In ophthalmic surgery, the injection pressure must not exceed the injection pressure limit (a certain upper limit), so real-time observation can be carried out during the experiment.

[0073] The above injection method can effectively avoid the problem of excessive tissue impact caused by excessive pressure from pure liquid or pure gas pumps.

[0074] The present invention has been described in detail above through embodiments, but the content described is only an exemplary embodiment of the present invention and should not be considered as limiting the scope of the present invention. The scope of protection of the present invention is defined by the claims. Any technical solutions designed by those skilled in the art using the technical solutions described in the present invention, or designed by those skilled in the art under the inspiration of the technical solutions of the present invention, within the substance and protection scope of the present invention, to achieve the above-mentioned technical effects, or any equivalent changes and improvements made to the scope of the application, should still fall within the patent protection scope of the present invention.

Claims

1. A gas-buffered injection system for retinal intravenous injection surgery, characterized in that: The device includes a flow meter, a three-way connector (A), a pressure sensor, an injector, and a miniature linear servo actuator. The three ports of the three-way connector (A) are respectively connected to the flow meter, the pressure sensor, and the injector. The injector is connected to the miniature linear servo actuator, and a pressure sensor is provided at the rear end of the miniature linear servo actuator. The pressure sensor is used to measure the pressure of the gas at the top of the three-way connector (A), below which is a viscous liquid. The pressure sensor is used to push the push rod under pressure. The flow meter outlet is connected to a syringe device, and the flow meter, pressure sensor and miniature linear servo driver are all connected to the control device. The control device sets the starting speed of the miniature linear servo drive push rod movement based on the optimal injection volume curve and flow rate limit value required by the injection target. Turn on the start switch of the micro linear servo driver. The control device adjusts the push rod movement distance of the micro linear servo driver in real time according to the optimal injection volume curve and the feedback data of the air pressure sensor, and performs injection according to the optimal injection volume curve. The formula for the distance y that the push rod travels is: ; Where R is the radius of the push rod, and V is the volume of the viscous liquid. This is the initial air pressure. This represents the current air pressure. It is the initial volume of air; and V is measured by a pressure sensor; V is obtained from the optimal injection volume curve.

2. The gas-buffered injection system for retinal vein injection surgery as described in claim 1, characterized in that: The push rod of the miniature linear servo driver and the handle of the injector are both provided with threaded holes and connected by screws.

3. The gas-buffered injection system for retinal vein injection surgery as described in claim 1 or 2, characterized in that: Both the sampler and the miniature linear servo driver are fixed to the base.

4. The gas-buffered injection system for retinal vein injection surgery as described in claim 3, characterized in that: The rear part of the injector is located inside the base, and a cover A is fixed on the base. The cover A has a groove that matches the flange edge in the middle of the injector, and the flange edge is embedded in the groove.

5. The gas-buffered injection system for retinal vein injection surgery as described in claim 3, characterized in that: The miniature linear servo driver is located inside the base, and a cover B is fixed on the base. The cover B has a fixing groove that matches the bearing of the pressure sensor at the rear end of the miniature linear servo driver, and the bearing is located in the fixing groove.

6. The gas-buffered injection system for retinal vein injection surgery as described in claim 1, characterized in that: A three-way connector B is provided between the three-way connector A and the injector. The three ports of the three-way connector B are respectively connected to the three-way connector A, the injector, and the supplemental viscous liquid syringe.

7. The gas-buffered injection system for retinal vein injection surgery as described in claim 1, characterized in that: The flow meter has a full-scale flow rate of 1 ml / min and an accuracy of 5%; the injector has a capacity of 1 ml and a scale range of 30 mm.

8. The gas-buffered injection system for retinal vein injection surgery as described in claim 1, characterized in that, The control device receives feedback data from the pressure sensor, calculates the injection pressure, and ensures that the injection pressure does not exceed the injection pressure limit. Otherwise, it immediately reduces the push rod movement speed of the micro linear servo drive. The control device also receives feedback data from the flow meter, outputs a true volume curve based on the conversion relationship between flow rate and volume, and compares it with the optimal injection volume curve.

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