Peripheral central venous catheter placement was used in clinical practice in the 1980s, and is now largely recognized by medical staff and patients. Its ultra-thin, highly biocompatible catheter is inserted into the superior vena cava by anterior cubital vein puncture for alternate treatment, providing reliable venous access, which can replace central venous catheterization without the complications of central venous catheterization. The first condition for successful puncture is an ideal catheterized vein. For patients with good local vascular conditions, the method of visual observation and touch estimation can be used to evaluate the post-vascular catheterization. For patients with edema, obesity, repeated chemotherapy and due to long-term infusion, the success rate of conventional puncture is low. How to improve the success rate of puncture catheter placement is a new topic facing the clinic. Under ultrasound guidance, PICC can visually display the anatomical structure of blood vessels. It has the advantages of real-time guidance, full visibility, shortening puncture time, and reducing complications. It not only reduces the pain of puncture patients, but also provides a safe and effective solution for nursing staff. The infusion route avoids the waste of medical resources.
Note: The PICC catheterization is completed by using MST technology under ultrasound guidance, and the catheterization site is moved from the cubital fossa to the upper arm, which reduces the friction and traction of the catheter due to limb activities, and reduces the impact of the catheter being stretched in the blood vessel. Stimulation of the blood vessel wall can reduce the complications of blood vessel-related infections and relieve the patient’s discomfort when the elbow bend position in the past, which is very beneficial for long-term catheter fixation.
1. The origin of ultrasoud-guided PICC catheter placement
The use of ultrasound-guided PICC puncture was first completed in 1997 at the Washington Medical Center by a nurse Claudette Boudreaus engaged in critical care, who was the first PICC team member. She gained experience from assisting doctors in internal jugular vein puncture, and was able to puncture intangible blood vessels under ultrasound guidance. She succeeded in PICC puncture in the expensive vein above the cubital fossa. From 1999 to 2001, approximately 10 nurses received professional training in these techniques at the Washington Hospital Center. During this period, the success rate of PICC placement at the bedside was 65% to 91%. In the past 10 years, many medical studies have shown that the use of micro-intubation sheath technology and ultrasound guidance can greatly improve the success rate of PICC catheter placement.
Not all blood vessels can be cannulated. Ultrasound guidance is the best method and cannot be inserted blindly. 700 million catheters are inserted every year in the world. The United States accounts for 30%, all of which are intubated under the guidance of vascular ultrasound; other countries account for 70%, and 490 million are blind catheters.
Currently in the United States, ultrasound and micro-intubation sheath technology are used for upper arm PICC placement. This technical method has become the “gold standard” for professional nurses in various hospitals to place special tubes.
2. The choice of ultrasound-guided PICC catheterized Vein
Veins can be divided into two types: deep and shallow. Deep veins run on the deep surface of deep fascia and are accompanied by arteries of the same name, also called parallel veins; superficial veins run on the subcutaneous tissue and are generally called subcutaneous veins (see Figure 1). Because the upper limb vein stroke is shorter than the lower limb, the right side is shorter than the left side, and the superficial vein is easy to find. Therefore, the right upper limb superficial vein puncture tube is often chosen to reach the superior vena cava through the axillary vein. PICC generally chooses the elbow superficial cubital vein for catheterization, the most expensive vein is the first choice, followed by the median cubital vein or the cephalic vein. For patients who cannot be catheterized through the elbow vein, the external jugular vein, axillary vein and femoral vein of the lower extremities, The saphenous vein and the popliteal vein can also be used as PICC catheters. PICC under ultrasound guidance should be the first choice for the expensive vein, because it is located in front of the elbow and has a large operating range, which is suitable for real-time monitoring by ultrasound personnel. At the same time, the expensive vein approach is the method with the least trauma and complications for central venous catheterization. It can significantly reduce the incidence of pneumothorax, hemothorax, air embolism and nerve damage.
3. Requirements for vascular ultrasound
A. Ultrasond machine used for limb vein examination should have the following characteristics: high spatial resolution, ultrasound frequency in 5M`～15MHz; high grayscale resolution (256 levels); It has the Doppler function of detecting low-velocity venous blood flow signals, which is helpful to judge the arteriovenous blood flow spectrum; it has the function of color Doppler or energy Doppler, which helps to determine the small veins and display the blood flow.
B. Probe type and frequency: The upper limb veins are relatively superficial, so linear array probes of 7.5M～10MHz should be used. Higher frequency probes are sometimes more effective. The veins of the lower extremities generally use 5M～7MHz linear array probes (subclavian veins, for large limbs, 3.5MHz convex array probes are needed for deep veins).
C. Preset conditions: select the vein inspection conditions set in the instrument to quickly enter the appropriate inspection state, and adjust at any time according to different veins and purposes during the inspection process.
D. Ultrasound guidance system specially used for PICC catheter placement: simple two-dimensional black-and-white vascular ultrasound plus a special guidance system, the identification is clear at a glance, and the instrument is easy to move, easy to go to the ward, easy for nurses to operate, and easy for nurses to master. The price is relatively cheap, and it can help complete the PICC catheterization operation clinically.
The ultrasound guidance system can automatically calculate the needle angle according to different blood vessel depths, and can display the blood vessel size and depth. Comparing the target blood vessel and the blood vessel size diameter chart on the screen, the naked eye can intuitively judge the diameter of the blood vessel and the approximate catheter that can be inserted.
On the probe of the ultrasound system, there are a power switch, an operation button to adjust the image contrast, and a “cm” button to adjust the depth of the probe. The minimum image depth can be set to 1.5cm, and the maximum image depth can be set to 6cm, which can be adjusted according to the depth of the blood vessel. There are also buttons for image freeze and storage, which can be controlled in a sterile field when operated by one person.
The small probe not only has operation buttons, but also guide needle device. Inserting the needle at the angle of the guide needle system can directly enter the target blood vessel. For example, the depth of the blood vessel from the skin is 1cm. Choose a guide needle holder of 1cm. After the puncture needle is inserted, it is exactly at the midpoint of the 1cm deep blood vessel; The depth from the skin is 2cm. Choose a 2cm guide needle holder. The intersection point of the puncture needle after piercing the needle holder at the angle of the guide needle holder is exactly at the midpoint of the 2cm deep blood vessel. Using the guide needle system can hit the nail on the nail with high accuracy.
4. Patient position during intravenous ultrasound examination
During intravenous ultrasound examination, the examination room and the patient should maintain sufficient temperature to prevent the constriction of peripheral blood vessels from causing the veins to become thin, making ultrasound examination difficult. Ultrasound examination of the upper extremities usually takes the supine position, the upper extremity is in abduction and external rotation, the palm is upward, the abduction angle is 60 to 90 degrees with the trunk, and the upper extremity is fully exposed (the superficial venous system of the upper extremity is superficial, mostly located under the skin, and must be injected
Be careful to press the probe lightly, otherwise the vein will be compressed and cannot be reached). The lower limbs are taken with head high and feet low. People with severe breathing difficulties can also take a semi-recumbent position.
5. The content of intravenous ultrasound observation
The observation content includes: vein variation, intima, echo in the lumen, etc.; whether there are spontaneous blood flow signals and blood flow filling in the venous lumen; compression test, extruding distal limb test and low test can observe the vein Whether there is thrombus, venous valve function, etc.
6. The Characteristristics of normal veins
A. B/W ultrasound image: The veins of normal limbs have the following four ultrasound characteristics. ①The vein wall is thin; ②The intima is flat and smooth; ③The blood flow in the lumen is no echo, and the high-resolution ultrasound instrument can show the flowing red blood cells with weak echo; ④Compressibility, the pressure of the probe can make the lumen disappear.
B. Color Doppler: The veins of the normal limbs show a single direction of return blood flow signal and fill the entire lumen. Superficial veins or venules may have no spontaneous blood flow, but when the distal limbs are squeezed, the lumen can be A blood flow signal appears. When a certain external pressure is used, the venous lumen disappears, and the blood flow signal also disappears.
C. Pulse Doppler: Normal limb veins have five Doppler characteristics, namely spontaneity, phase, low test, squeeze distal limb test blood flow signal enhancement and unidirectional blood flow.
7. Evaluation of PICC catheterized vein under ultrasound and determination of puncture point
1 Vascular assessment
During the puncture, the evaluation of the blood vessel range should not be too small. Scan the blood vessel with 2 fingers on the cubital fossa, scan the depth, direction and bifurcation position of the blood vessel along the blood vessel; measure whether the diameter of the blood vessel is sufficient to accommodate the selected catheter; observe the periphery of the blood vessel The structure of the blood vessel, especially in the case of accompanying arteries, whether there is any vascular variation, such as accompanying arteries or vascular malformations, should be avoided; whether there are blood clots in the blood vessels, determine whether the blood vessels are unobstructed, etc.
2 Determination of the puncture point
When choosing the puncture point, avoid the venous valve, avoid the branch veins, and puncture the thicker veins to avoid the adverse factors in the blood vessel. Most of the ultrasound-guided PICC catheters are punctured at the expensive veins of the upper arm above the cubital fossa. The expensive veins of the upper arm are easier to locate and travel better. It avoids the connection between the middle branch vein and the expensive vein Point, the blood vessels in this area are thicker than the blood vessels in the cubital socket, and the length of the catheter that needs to be inserted will be shorter. In addition, the blood flow at this location is greater and it is not easy to cause damage to the blood vessel wall. At the same time, there is less friction and traction on the catheter due to limb activities in this position, thereby reducing the stimulation of the catheter’s movement in the blood vessel to the blood vessel wall, thereby reducing the incidence of complications such as blood vessel-related infections. It reduces the patient’s discomfort when the elbow is bent in the position of the tube in the past, and it is very beneficial for long-term catheter fixation.
8. Improved Sedinger puncture technique
The method of percutaneous catheter insertion was invented by a Swedish radiologist named Sedinger. Sedinger puncture technique is also called micro cannulation sheath technology (MST). It is often used in central venous puncture catheterization. How to apply Seidinger puncture technique to PICC catheterization flexibly to improve the success rate of PICC catheterization? There are three ways to apply Sedinger puncture technique in PICC catheter placement: “Blind plug method”, “Indirect method” under ultrasound guidance, “Direct view method” under ultrasound guidance.
(1) Blind plug method
“Blind plug method” refers to the method of puncturing the blood vessel and inserting the PICC with the improved Sedinger technique under naked eye observation or hand touch (without any instruments). Indications of “Blind Plug Method”
a. The blood vessels are thin, but can be seen or faintly visible with the naked eye.
b. The puncture with the traditional 14G or 16G needle is unsure.
c. The blood vessel resources are limited, only one, once the puncture fails, the catheter cannot be placed, which affects the treatment.
d. Without ultrasound equipment, the patient’s blood vessel condition is poor, and PICC catheterization is required for treatment.
e. Agitated and uncooperative patients.
At present, due to the limitations of various conditions, the technology of PICC catheter placement under ultrasound guidance has not been popularized. In patients with very thin blood vessels, using the “blind plug method” will increase the success rate of PICC catheter placement. If the puncture fails, because the needle is thinner, it will damage blood vessels and tissues much less. It will not affect the use of blood vessels and can be punctured again.
(2) “Indirect method” guided by ultrasound
Use a vascular ultrasound instrument to scan the veins that can be placed, then mark them according to the direction of the blood vessels. Use the MST micro-cannula sheath puncture technique to perform puncture. After the puncture is successful, the PICC catheter is inserted. We call this method It is the “indirect method” under ultrasound guidance.
Indications of “indirect method” under ultrasound guidance
a. The blood vessels are thin, poor and invisible to the naked eye.
b. It is impossible to puncture the catheter with the traditional 14G or 16G puncture needle.
c. There is no independent tube B-ultrasound and no application conditions.
d. Those who are restless, uncooperative, and lose the “direct vision method” under ultrasound guidance.
(3) “Direct vision” under ultrasound guidance
The PICC catheter is placed under direct vision puncture under the guidance of vascular ultrasound. We call this method the “direct vision” under ultrasound guidance.
Indications of “direct vision” under ultrasound guidance
1. Patients with edema: due to the edema caused by the disease, intravenous treatment cannot be performed. (1) Systemic edema caused by secondary severe malnutrition combined with hypoproteinemia; (2) End-stage renal edema; (3) Hypothyroidism; ⑷ Drug allergic systemic skin lesions and edema (a relative indication).
2. Simple obesity patients: patients with BMI> 28, because of obesity, the elbow veins can not be touched.
3. Patients who have stopped chemotherapy for a long period of time or need intravenous infusion treatment: Due to repeated chemotherapy or intravenous infusion treatment, the patient’s superficial veins are damaged and are cord-shaped, and cannot be used. Such as patients with advanced tumors, patients with viral meningitis, and long-term nutrition supporters.
4. The failure of traditional PICC placement.
5. The patient requires a tube above the elbow to improve the quality of life.
The mixed application of “direct view method” and “indirect method” has the function of mutual synergy. In patients with poor vascular conditions and difficulty in traditional blind catheter insertion, when PICC catheterization is performed under ultrasound guidance, it can be seen that the diameter of the patient’s blood vessel is usually about 1.34mm. When the catheter is inserted under ultrasound guidance, we look at the blood vessel Cross section. The “direct vision” puncture uses a puncture method that is perpendicular to the blood vessel. That is to say, if the diameter of the patient’s blood vessel is 1.34mm thick, the longest distance of the needle in the blood vessel should be less than 1.34mm. After the puncture is successful, agitation is encountered A twist of the upper limb of a patient who does not cooperate can easily cause the needle to fall out of the blood vessel with a diameter of about 1.34mm, which makes it difficult to feed the guide wire and fails to insert the tube. After encountering the failure of catheter placement in such patients, you can try to use the “indirect method”. After detecting the veins that can be catheterized with the vascular ultrasound instrument, draw the markings according to the blood vessel’s course, and then leave the ultrasound screen, use 20G or 21G The trocar needle is punctured with the skin at an angle of 15 degrees. After seeing the blood return, the angle is flat and the cannula is fed into the blood vessel 3 to 4 cm. Because the length of the cannula in the blood vessel is longer than the length of the needle in the blood vessel of the “direct vision method” It is increased by more than 20 times, which greatly improves its stability. When the upper limbs of such patients are twisted, it is difficult to make the cannula out of the blood vessel, thus increasing the success rate of PICC intubation for such patients.
(4) Advanced PICC placement method
The improvement of the direct vision method, the use of MST microcannula sheath puncture technology to insert a PICC catheter into the upper arm of the vascular ultrasound guided puncture, which is the most advanced PICC insertion method in the world.
The application of MST improves the success rate of PICC catheterization and reduces tissue damage, especially when the first needle puncture is unsuccessful, its advantages and effects are more obvious and prominent.
9. Advantages of PICC tube placement with MST technology under ultrasound guidance
A. Guided puncture: PICC puncture under ultrasound guidance can visually display the position of blood vessels and anatomical structures, increase the accuracy of puncture, and has the advantages of real-time guidance, full visibility, short puncture time, and high puncture success rate.
B. Guide PICC tube position: The US Food and Drug Administration recommends that the ideal position of the PICC tip is in the superior vena cava. When the catheter is not placed in the superior vena cava, the incidence of catheter dysfunction and complications will increase. Ultrasound can accurately locate and guide the catheter to the correct position. By compressing the internal jugular vein on the same side and the necessary head position assistance, the PICC tube can be guided to the superior vena cava. For ectopic catheters, ultrasound can observe the position of the catheter in real time, and guide the operator to correct the ectopic position timely and intuitively, reduce the blockage, venous thrombosis, and thrombophlebitis caused by the ectopic catheter, extend the catheter indwelling time, and avoid radiation Radiation to patients and operators. The positioning system at the head end of the new style can also be connected to the ECG, which can determine whether the catheter enters the heart in time.
C. Evaluation after puncture Ultrasound can evaluate vascular complications such as venous thrombosis and thrombophlebitis after PICC catheterization. It also has an important guiding role in evaluating catheter indwelling time and catheter extubation time.
D. Ultrasond guidance of upper arm catheterization can realize upper arm puncture catheterization. Compared with the traditional PICC catheterization, its puncture site has changed, from the elbow to the upper arm, which reduces the friction and traction of the catheter by the limb activities and avoids In order to reduce the occurrence of phlebitis, according to relevant data records, in more than 500 cases of puncture and intubation of the upper arm under ultrasound guidance, no case of phlebitis occurred, reducing the complications of vascular-related infections.
E. Solved the problem of patients with poor vascular conditions. With the increase in the number of chemotherapy and catheterization, many patients have no blood vessels in the elbow fossa that can be touched or visible, and the vascular conditions are getting worse and worse. Blind puncture with traditional PICC trocars (14G or 16G) with a relatively thick puncture effect is becoming more and more difficult. The use of bedside vascular ultrasound and micro-intubation sheath technology can solve this problem.
In short, the success rate of using ultrasound to guide PICC catheter placement mainly depends on the operator’s experience and the patient’s vascular condition. Ultrasound has the characteristics of real-time dynamics and can accurately deliver the puncture needle into the vascular cavity under ultrasound guidance, greatly improving the disposable The success rate of puncture catheterization. But this has a lot to do with the operator’s experience, and requires professional technical training and hand-eye coordination training, as well as a practical process.
