Method for detecting venous access before high-pressure injection of CT enhanced contrast agent

Abstract

The invention discloses a method for detecting a venous access before high-pressure injection of a CT enhanced contrast agent, and relates to the technical field of CT examination. Whether the bearing capacity of the blood vessel of the patient can bear the standard injection speed of the contrast agent or not can be judged through pre-examination, if normal saline exosmosis or pain does not occur in the blood vessel of the patient in the pre-detection process, it is indicated that the blood vessel meets the high-pressure injection condition, and injection can be conducted according to the high-pressure requirement; if liquid exosmosis occurs during pre-detection, the blood vessel does not meet the high-pressure injection condition, and the blood vessel needs to be replaced additionally to ensure the treatment safety of the patient.

Description

Technical Field

[0001] The invention relates to the technical field of CT examination, and in particular provides a method for detecting a venous access before high-pressure injection of a CT enhanced contrast agent. Background Art

[0002] CT enhanced examination is a method of performing CT scanning after intravenous injection of a certain dose of iodine-containing contrast agent. Contrast agents are increasingly used in conventional enhanced scanning, vascular imaging, and perfusion scanning. At present, the nursing staff first establishes an intravenous access for the patient with an indwelling needle in the injection room, and manually flushes the tube with 10ml of normal saline to check whether the intravenous access is normal and meets the conditions for high-pressure injection of contrast agents. Under normal circumstances, high-pressure injection of contrast agents refers to injection at a speed of 2.0-6.0mL / s. During the period of CT enhanced high-pressure injection of drugs, the patient is in the CT examination operating room. In the first 10s of high-pressure injection, the nurse touches the punctured blood vessel to feel whether there is extravasation. For example, if the skin is edematous, it means that extravasation has occurred and the blood vessel needs to be replaced for injection. If there is no abnormality, the radiation-proof door will be closed immediately. The patient's injection situation can only be observed from a distance through the radiation-proof lead glass, and the specific situation of the injection cannot be directly known. Only when the patient feels uncomfortable and raises his hand to indicate, the nursing staff can know whether there is extravasation.

[0003] When extravasation first occurs, the dose of contrast agent extravasation is small, which will only cause edema and pain under the patient's skin. However, when the dose of extravasation is large, a large amount of contrast agent extravasation can lead to serious consequences such as skin ulcers, soft tissue necrosis and compartment syndrome, posing a potential risk of medical accidents. When the patient is already able to feel discomfort, a large amount of contrast agent has already extravasated, and the nursing staff cannot stop the injection of contrast agent at the first time of extravasation, which can easily cause serious damage to the patient's body tissues. Summary of the invention

[0004] The present invention provides a method for detecting venous access before high-pressure injection of CT enhanced contrast agent, which is used to solve the problem that extravasation is easy to occur during contrast agent injection, resulting in injury to patient body tissues.

[0005] The technical solution of the present invention is as follows: A method for detecting venous access before high-pressure injection of CT enhanced contrast agent comprises the following steps: S1, pre-examination, use a syringe to inject normal saline into the vein at the injection rate of contrast medium; S2. Observe whether there is leakage of saline solution under the skin; S3, if there is no leakage, inject contrast agent into the vein and perform CT enhancement examination; if there is leakage, proceed to step S4; S4, select another intravenous injection of normal saline, the injection speed of the normal saline is lower than the injection speed in step S1, the injection speed of the normal saline is gradually increased until subcutaneous leakage occurs, and the injection speed lower than the injection speed when leakage occurs is selected as the injection speed of the contrast agent; S5. Select another intravenous contrast agent and inject the contrast agent into the vein according to the injection speed obtained in step S4.

[0006] In this scheme, a preliminary examination can be used to determine whether the patient's blood vessels can withstand the standard injection speed of the contrast agent. If the patient's blood vessels do not show extravasation of saline during the preliminary examination, it means that injecting the contrast agent at the standard injection speed will not cause extravasation, and the contrast agent can be injected at the standard injection speed. If extravasation of saline has occurred during the preliminary examination, it means that the patient's blood vessels cannot be injected at the standard injection speed of the contrast agent. At this time, saline can be injected at a smaller injection speed to determine how much injection speed the patient's blood vessels can withstand, so as to select a suitable injection speed to inject the contrast agent. For example, when extravasation occurs when the injection speed is increased to a certain value, it means that extravasation of saline will occur under this pressure. At this time, a value less than the injection speed can be selected as the injection speed of the contrast agent to ensure that the contrast agent will not extravasate during the injection process.

[0007] The injection of contrast agents requires high pressure and high speed injection, the purpose of which is to minimize the dilution of the contrast agent and to maximize the image clarity of the CT examination. Manual injection by nursing staff cannot accurately simulate this injection speed and injection rate. For this reason, a drive mechanism is used to push the syringe when injecting normal saline.

[0008] In this solution, a driving mechanism is used to push the syringe. The characteristic of the driving mechanism is that it does not require manpower and can push the syringe more efficiently and stably, ensuring that the real injection situation can be fully simulated during the pre-inspection to ensure the accuracy of the pre-inspection.

[0009] Preferably, the driving mechanism includes a base plate, a linear motor and a fixed sleeve, the linear motor and the fixed sleeve are respectively fixed to the base plate, the end of the fixed sleeve abuts against the end of the syringe away from the push rod, a through hole is provided in the middle of the fixed sleeve, the through hole is used for a pipeline to pass through, one end of the pipeline is connected to the syringe, and the other end is provided with a needle, the linear motor abuts against the push rod of the syringe, and the linear motor is used to push the push rod of the syringe to discharge the physiological saline in the syringe.

[0010] In this solution, a linear motor can be used to directly push the syringe, without the need for a complex transmission structure, thus reducing the cost of the drive mechanism.

[0011] Preferably, a pressure sensor is provided at one end of the linear motor against the syringe, and the driving mechanism is also configured with a controller. The pressure sensor and the linear motor are electrically connected to the controller respectively, and the controller controls the linear motor according to the signal of the pressure sensor to keep the pressure of the syringe stable.

[0012] In this solution, a pressure sensor is provided to detect the injection speed of the syringe, so that the injection speed can be kept stable, thereby ensuring that the contrast agent injection speed can be accurately simulated.

[0013] Preferably, a display screen is arranged on the bottom plate, the display screen is electrically connected to the controller, and the display screen is used to display the current pressure value of the pressure sensor.

[0014] In this solution, a display screen is provided to visually observe the injection speed, avoid inaccurate pressure, and improve the accuracy of pre-inspection.

[0015] When judging whether the saline solution has extravasated, the nursing staff mainly observes whether there is fluid accumulation, swelling, etc. under the skin. If the fluid accumulation and swelling are not obvious, the nursing staff may not observe them, which may easily lead to misjudgment. For this reason, the saline solution includes a fluorescent detector, and the distribution of the fluorescent detector is observed to judge whether the saline solution has extravasated.

[0016] In this scheme, when the physiological saline extravasates, the fluorescent detection agent will also extravasate. If the fluorescent detection agent extravasates to the subcutaneous part, the injection site can be illuminated by an external light source. The light emitted by the light source passes through the skin, causing the subcutaneous fluorescent detection agent to glow. At this time, it can be observed whether there is extravasation. By observing extravasation with a fluorescent detection agent, even if the extravasated physiological saline is very small, it can be accurately judged by the fluorescent position, which can solve the problem of misjudgment.

[0017] In order to facilitate the observation of the fluorescent detection agent, when observing whether the normal saline has extravasated, the fluorescent detection agent under the skin is excited by the light source to emit fluorescence, and the skin is photographed by a camera to identify the diffusion of the fluorescent detection agent under the skin. If the fluorescent agent diffuses to areas outside the blood vessels, it means that the normal saline has extravasated.

[0018] In this scheme, the method of photographing the skin with a camera can improve the clarity, show the position of the fluorescent detection agent more clearly, and make it easier to judge whether the normal saline has extravasated.

[0019] Preferably, when injecting normal saline in step S4, the injection speed of the normal saline is divided into multiple fixed pressure values ​​and continuously injected in stages. If extravasation occurs during continuous injection at a fixed pressure value, the previous fixed pressure value is the injection speed of the contrast agent.

[0020] In this scheme, continuous injection at multiple fixed pressure values ​​is more convenient to judge the injection speed when saline leaks. When the injection speed that causes extravasation is obtained, the nursing staff can also select the injection speed of the contrast agent more quickly, thereby improving the efficiency of the examination.

[0021] Preferably, in step S4, the display screen displays two pressure values, which are respectively the current injection speed and the injection speed in the previous stage.

[0022] In this scheme, the injection speed of the previous stage is displayed on the display screen. When extravasation is found, the injection speed of the previous stage can be visually viewed. The injection speed of the previous stage displayed on the display screen is the injection speed of the contrast agent.

[0023] Preferably, when performing the injection, a vascular imager is used to observe the change in the width of the blood vessel, and the nature of the blood vessel is judged by whether the width of the blood vessel can change. If the blood vessel can expand and widen during the injection, the operation is carried out according to the original steps; if the blood vessel cannot expand and widen during the injection, the procedure goes directly to step S4.

[0024] In this scheme, if the patient's blood vessels are fragile due to old age, lack of exercise or poor eating habits, then the blood vessels are prone to extravasation under high pressure. By observing whether the blood vessels expand during injection to determine the patient's vascular status, patients with fragile blood vessels can be distinguished in advance, which can reduce the detection operation, improve detection efficiency and reduce patient pain.

[0025] Beneficial effects of the present invention: The pre-examination step of the present invention can detect the patient's veins before injecting the contrast agent to determine whether the patient's veins will extravasate when the contrast agent is injected. If extravasation occurs, the pressure that the patient's blood vessels can withstand will be detected again, and the contrast agent can be injected according to the detected pressure. In step S1 and step S4, the patient and the nursing staff are both outside the examination room. The nursing staff can detect extravasation at the first time and control the extravasation amount within a very small range, thereby avoiding a large amount of extravasation of the contrast agent during the injection process, thereby avoiding a large amount of extravasation causing harm to the patient. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present invention, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 This is a schematic diagram of a process of Embodiment 1 of the present invention; Figure 2 A top view of the drive mechanism and the syringe of the present invention; Figure 3 is a cross-sectional view of a fixing sleeve of the present invention; Figure 4 This is a flow chart of the second embodiment of the present invention.

[0028] In the above drawings, the corresponding reference numerals are as follows: 1. Linear motor; 2. Pressure sensor; 3. Syringe; 4. Fixed sleeve; 5. Pipeline; 6. Display screen; 7. Emergency stop switch; 8. Start switch; 9. Base plate; 10. Sleeve; 11. Step. DETAILED DESCRIPTION

[0029] In conjunction with the accompanying drawings, the technical solution of the present invention is clearly and completely described through specific implementation methods of the embodiments of the present invention. Embodiment 1

[0030] like Figure 1 As shown, this embodiment 1 provides a method for detecting venous access before high-pressure injection of CT enhanced contrast agent, comprising the following steps: S1, pre-examination, using syringe 3 to inject normal saline into the vein at the injection speed of contrast agent; when the patient's vein can withstand the injection speed of contrast agent, the injection of normal saline will not cause the patient's blood vessels to rupture and extravasate; therefore, when normal saline extravasates, it means that extravasation will also occur when contrast agent is injected at standard pressure; S2. Observe whether there is leakage of saline solution under the skin. During the observation, you can observe whether the skin becomes locally red or edematous to determine whether there is extravasation. S3, if there is no leakage, inject contrast agent into the vein and perform CT enhancement examination. If there is leakage, proceed to step S4; if there is no extravasation during the pre-examination, it means that the standard injection speed of contrast agent will not cause extravasation, and contrast agent can be directly injected. On the contrary, if extravasation occurs, it means that contrast agent cannot be injected at standard pressure; S4, select another vein to inject normal saline. The injection speed of normal saline is lower than the injection speed of step S1. The injection speed of normal saline gradually increases until subcutaneous leakage occurs. The injection speed lower than the injection speed when leakage occurs is selected as the injection speed of contrast agent. The vein that has extravasation during the pre-examination has already extravasated, so it is necessary to select another vein for injection. During the injection process, the injection speed is gradually increased in stages. In other words, inject at a pressure value for a period of time. If there is no extravasation during this process, inject at a higher pressure value for a period of time, and then observe whether there is extravasation, until the injection speed is close to the standard injection speed of the contrast agent or extravasation occurs. When extravasation is found, the injection speed of the previous stage is selected as the injection speed of the contrast agent to ensure that there is no extravasation when the contrast agent is injected.

[0031] S5. After determining the appropriate injection speed, another vein can be selected to inject the contrast agent, and the injection speed of the contrast agent is the injection speed obtained in step S4. The reason for selecting another vein is that the original vein has ruptured and extravasated, and in order to avoid the injected contrast agent from extravasating from the ruptured position, another vein is selected to inject the contrast agent.

[0032] During the injection process, the injection speed of the contrast agent needs to be simulated, but the nursing staff cannot accurately simulate the injection speed, nor can they maintain the injection speed unchanged. Therefore, the present application drives the syringe 3 through a set of driving mechanisms, so that the syringe 3 can maintain a stable and accurate pressure to inject saline.

[0033] like Figure 2 As shown, the driving mechanism includes a linear motor 1, a base plate 9 and a fixing sleeve 4. The fixing sleeve 4 is arranged on the base plate 9. The fixing sleeve 4 is used to fix the syringe 3. The linear motor 1 is also arranged on the base plate 9. The linear motor 1 is used to push the syringe 3. The linear motor 1 is against the push rod of the syringe 3. When the linear motor 1 is working, the linear motor 1 will push the push rod of the syringe 3 to move, and the fixing sleeve 4 is used to abut against the other end of the syringe 3 to fix the barrel of the syringe 3. The linear motor 1 cooperates with the fixing sleeve 4 to realize the injection action of the syringe 3, so that the syringe 3 outputs physiological saline.

[0034] like Figure 3 As shown, the structure of the fixed sleeve 4 is a cylindrical structure, which includes two sections of through holes with different diameters. The two sections of through holes are connected, and a step 11 structure is formed at the connection of the two through holes. The through hole with a large diameter is used to accommodate the barrel of the syringe 3, and the through hole with a small diameter is used for the passage of the pipe 5. One end of the pipe 5 is connected to the syringe 3, and the other end of the pipe 5 is provided with a needle. The liquid output by the syringe 3 is input into the patient's vein through the pipe 5 and the needle. The step 11 in the fixed sleeve 4 abuts against the end of the syringe 3 to prevent the syringe 3 from moving along the axial direction. The fixed sleeve 4 also includes a plurality of sleeves 10, and the plurality of sleeves 10 are mutually sleeved to form a multi-layer structure. The function of providing the plurality of sleeves 10 is to change the aperture of the through hole with a large diameter of the cylindrical structure. For example, if the innermost sleeve 10 is removed, the aperture of the through hole will increase, and it can be used to fix the syringe 3 with a larger diameter; similarly, if a sleeve 10 is inserted into the through hole, the aperture of the through hole will be reduced, and it can be used to fix the syringe 3 with a smaller diameter. The aperture of the through hole used to fix the syringe 3 is equal to the diameter of the smallest sleeve 10.

[0035] A pressure sensor 2 is provided at the contact position between the linear motor 1 and the push rod of the syringe 3. The pressure sensor 2 is used to detect the pressure applied by the linear motor 1 to the syringe 3. The injection speed can be determined by the pressure applied by the linear motor 1 to the syringe 3. A controller is also included. The controller controls the linear motor 1 according to the pressure signal detected by the pressure sensor 2 so that the pressure applied by the linear motor 1 to the syringe 3 is kept stable.

[0036] In step S4, it is also necessary to detect the appropriate pressure that the patient's vein can withstand by injecting physiological saline with different pressures, and in the case where a pressure sensor 2 is provided, injection with different pressures can be achieved. In step S4, the nursing staff needs to know the current injection speed, so a display screen 6 can also be configured. The display screen 6 is used to display the pressure value detected by the pressure sensor 2, and can also display the pressure value of the previous stage. When extravasation is found during the injection of physiological saline, it means that the current injection speed will cause extravasation, so the nursing staff can use the pressure value of the previous stage displayed on the display screen 6 as the injection speed of the contrast agent. The injection speed of the previous stage is displayed on the display screen 6, and the nurse does not need to record it manually.

[0037] When extravasation of saline occurs, the injection needs to be stopped in time to avoid excessive extravasation. Therefore, an emergency stop switch 7 can be configured for the drive motor. The emergency stop switch 7 can be a button switch arranged on the bottom plate 9. The emergency stop switch 7 is electrically connected to the controller. The emergency stop switch 7 sends a signal to the controller, and the controller stops the linear motor 1, so that the linear motor 1 stops giving pressure to the syringe 3, thereby stopping the injection. It should be noted that when the emergency stop switch 7 gives a signal to the controller, the controller will also control the display screen 6 so that the reading displayed on the display screen 6 no longer changes, which is convenient for nursing staff to observe the injection speed of the previous stage when extravasation occurs, and is also used to solve the problem that the value detected by the pressure sensor 2 changes after the linear motor 1 stops working, which affects the reading change of the display screen 6.

[0038] Similarly, a start switch 8 is also provided on the base plate 9, and the start switch 8 is used to start the linear motor 1 and restart the linear motor 1. Since the working modes of the linear motor 1 in step S1 and step S4 are different, the start switch 8 includes two. When different start switches 8 are pressed, the controller makes the linear motor 1 work in different working modes. For example, when one of the start switches 8 is pressed, the controller controls the linear motor 1 to extend and push the syringe 3 until the pressure value detected by the pressure sensor 2 reaches the standard injection speed of the contrast agent. The controller controls the linear motor 1 according to the pressure value detected by the pressure sensor 2, and maintains the detection value of the pressure sensor 2 at the standard injection speed of the contrast agent to simulate the injection of the contrast agent. When the other start switch 8 is pressed, the controller controls the linear motor 1 to start working, and regulates the linear motor 1 according to the pressure value detected by the pressure sensor 2, so that the pressure values ​​maintain different pressure values ​​respectively, and realize phased injection. The two start switches 8 can be set to different colors, and text descriptions can be set at the corresponding positions of the base plate 9 to distinguish the functions of the two start switches 8.

[0039] The injected saline solution may include a fluorescent detector, which emits fluorescence when exposed to light of a specific wavelength, such as light in the wavelength range of 750nm-1100nm. When the saline solution extravasates into the subcutaneous tissue, the fluorescent detector in the saline solution will also diffuse into the subcutaneous tissue. Therefore, the injection site is illuminated by external light, the light passes through the skin and illuminates the fluorescent detector under the skin, and then the injection site is photographed by a camera, and the fluorescence range can be used to determine whether the vein has extravasated. If extravasation occurs, the fluorescent detector will penetrate into the subcutaneous tissue with the saline solution, and the camera will capture a large range of irregular fluorescence under the skin. When no extravasation occurs, the fluorescence is distributed along the direction of the vein, and there will be no range-type diffusion. Therefore, by observing the fluorescence range captured by the camera, it can be determined whether the saline solution has extravasated.

[0040] In order to observe the fluorescence range more intuitively, a filter can be set on the camera. The filter only allows light of a specific wavelength to pass through, thereby filtering out other light interference, making the fluorescence more obvious in the picture taken by the camera, and making it easier for nursing staff to observe the fluorescence position more clearly. The wavelength range allowed by the filter overlaps with the wavelength range of fluorescence, allowing the fluorescence to pass through the filter, so that the camera can capture the fluorescence range. Embodiment 2

[0041] The second embodiment provides a method for detecting venous access before high-pressure injection of CT enhanced contrast agent. Different from the first embodiment, the second embodiment also displays the width of the blood vessel through a blood vessel imager, and determines whether the blood vessel can withstand the injection conditions based on the expansion state of the blood vessel.

[0042] like Figure 4 As shown, before the injection, a blood vessel imager is used to illuminate the injection site to make the vein at the injection site visible, and then the injection step of step S1 is performed. During the injection, the width change of the injected blood vessel is observed. If the blood vessel expands and widens, it means that the patient's blood vessel has good elasticity; if the blood vessel does not expand and widen, it means that the patient's blood vessel is fragile and not suitable for high-pressure injection. By observing the expansion state of the blood vessel, it is first determined whether the patient is suitable for high-pressure injection. For patients with fragile blood vessels, the appropriate injection pressure is directly detected from step S4.

[0043] For patients with elastic blood vessels, after the injection in step S1 begins, the injection pressure is controlled by observing the changes in the patient's blood vessel expansion. If the blood vessel expands significantly, it means that the blood vessel cannot withstand high-pressure injection. At this time, the injection method of step S4 can be switched to increase the injection pressure from low to high. If the blood vessel expansion is not obvious, the test can be continued according to steps S2 and S3.

[0044] During the injection process, if the patient expresses obvious pain but no extravasation or swelling caused by extravasation is observed, and if the blood vessels observed under the irradiation of the vascular imager are obviously expanded, it means that the injection speed should be reduced to reduce the injection pressure; if the blood vessels observed under the irradiation of the vascular imager are not obviously expanded, it means that the patient's pain is caused by puncture, and the original pressure can be maintained for injection.

[0045] It should be noted that the vascular imager is an existing device that is used to display the shadow of the blood vessels on the patient's hand and judge the expansion state of the blood vessels according to the change in the width of the shadow. If the width of the shadow changes quickly and the width changes greatly, the blood vessel expands quickly and the expansion is obvious. If the width of the shadow changes slowly and the width changes little, the blood vessel expands slowly and the expansion is not obvious. The specific width change value can be obtained based on clinical trials.

Claims

1. A method for detecting venous access before high-pressure injection of CT enhanced contrast agent, characterized in that: The following steps are involved: S1, pre-examination, use syringe (3) to inject normal saline into the vein at the injection rate of contrast agent; S2. Observe whether there is leakage of saline solution under the skin; S3, if there is no leakage, inject contrast agent into the vein and perform CT enhancement examination; if there is leakage, proceed to step S4; S4, select another intravenous injection of normal saline, the injection speed of the normal saline is lower than the injection speed in step S1, the injection speed of the normal saline is gradually increased until subcutaneous leakage occurs, and the injection speed lower than the injection speed when leakage occurs is selected as the injection speed of the contrast agent; S5. Select another intravenous contrast agent and inject the contrast agent into the vein according to the injection speed obtained in step S4.

2. A method for detecting venous access before high-pressure injection of CT enhanced contrast agent according to claim 1, characterized in that: When injecting physiological saline, the drive mechanism is used to push the syringe (3).

3. A method for detecting venous access before high-pressure injection of CT enhanced contrast agent according to claim 2, characterized in that: The driving mechanism comprises a base plate (9), a linear motor (1) and a fixed sleeve (4); the linear motor (1) and the fixed sleeve (4) are respectively fixed to the base plate (9); an end of the fixed sleeve (4) abuts against an end of the syringe (3) away from the push rod; a through hole is provided in the middle of the fixed sleeve (4); the through hole is used for a pipe (5) to pass through; one end of the pipe (5) is connected to the syringe (3) and the other end is provided with a needle; the linear motor (1) abuts against the push rod of the syringe (3); the linear motor (1) is used to push the push rod of the syringe (3) so that the physiological saline in the syringe (3) is discharged.

4. A method for detecting venous access before high-pressure injection of CT enhanced contrast agent according to claim 3, characterized in that: A pressure sensor (2) is provided at one end of the linear motor (1) that abuts against the syringe (3), and the drive mechanism is also provided with a controller. The pressure sensor (2) and the linear motor (1) are respectively electrically connected to the controller, and the controller controls the linear motor (1) according to a signal from the pressure sensor (2) so that the pressure of the syringe (3) remains stable.

5. A method for detecting venous access before high-pressure injection of CT enhanced contrast agent according to claim 4, characterized in that: The bottom plate (9) is provided with a display screen (6), the display screen (6) is electrically connected to the controller, and the display screen (6) is used to display the current pressure value of the pressure sensor (2).

6. The method for detecting venous access before high-pressure injection of CT contrast agent according to claim 1, characterized in that: The physiological saline contains a fluorescent detector, and whether the physiological saline has extravasated is determined by observing the distribution of the fluorescent detector.

7. A method for detecting venous access before high-pressure injection of CT enhanced contrast agent according to claim 6, characterized in that: When observing whether the normal saline has extravasated, the fluorescent detector under the skin is excited by the light source to emit fluorescence, and the skin is photographed by a camera to identify the diffusion of the fluorescent detector under the skin. If the fluorescent agent diffuses to areas outside the blood vessels, it means that the normal saline has extravasated.

8. The method for detecting venous access before high-pressure injection of CT enhanced contrast agent according to claim 5, characterized in that: When injecting normal saline in step S4, the injection speed of normal saline is divided into multiple fixed pressure values ​​and continuously injected in stages. If extravasation occurs during continuous injection at a fixed pressure value, the previous fixed pressure value is the injection speed of the contrast agent.

9. A method for detecting venous access before high-pressure injection of CT enhanced contrast agent according to claim 8, characterized in that: In step S4, the display screen (6) displays two pressure values, which are respectively the current injection speed and the injection speed of the previous stage.

10. The method for detecting venous access before high-pressure injection of CT enhanced contrast agent according to claim 1, characterized in that: During the injection, a vascular imaging device is used to observe changes in the width of the blood vessels. The change in the width of the blood vessels can be used to determine the nature of the blood vessels. If the blood vessel can expand and widen during injection, the operation is performed according to the original steps; if the blood vessel cannot expand and widen during injection, the operation directly proceeds to step S4.

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