At present, with the increasing number of uremic patients in China and the continuous improvement of dialysis technology and level, the number of hemodialysis patients and survival time are also on the rise, thus, the importance of vascular access, which is called the “lifeline” of uremic patients, is also becoming more and more prominent.
An ideal vascular access is the most coveted thing for every hemodialysis patient. It must meet the following conditions: it is easy to re-establish blood circulation and ensure sufficient blood flow to meet the needs of dialysis; it can be used for a long time without frequent intervention; and there are no obvious complications (thrombosis, infection, stenosis, aneurysm, etc.). It is known that vascular access is divided into temporary vascular access, semi-permanent vascular access and permanent vascular access. Among them, arteriovenous endovascular fistula, which is a permanent vascular access, is one of the most widely used modalities.
It has obvious advantages over other types of accesses (such as central venous placement, artificial vessels, etc.), such as.
1.Low incidence of stenosis;
2.Low rate of thrombosis;
3, repeated puncture, self-healing, low incidence of infection;
4, less complications and long service life.
The following article will give a brief introduction and experience of autologous arteriovenous endovascular fistula.
In 1962, Cimino, a blood banker, and Kenneth Appel, a surgeon, established the world’s first autologous arteriovenous endovascular fistula by anastomosing the patient’s forearm cephalic vein to the radial artery, thus creating a new milestone in vascular access. Over the decades, there have been some improvements in the way and site of the endovascular fistula, but to date, the Brescia-Cimino endovascular fistula, as it is called, remains an irreplaceable and ideal permanent vascular access.
How is an autologous arteriovenous endovascular fistula created? Autologous arteriovenous endovascular fistulae are created through a surgical procedure (autologous endovascular fistuloplasty), which involves subcutaneously connecting an artery and a superficial vein in close proximity to each other to artificially create a direct line between the arteries and veins in the body, thereby increasing blood flow to the superficial veins and facilitating puncture for hemodialysis.
Are all hemodialysis patients suitable for autologous arteriovenous endovascular fistuloplasty to establish an ideal vascular access? The answer is no. When patients have severe stenosis, significant thrombosis, or impaired venous return due to adjacent lesions in the large or central veins of the extremities, endovenous fistuloplasty should not be performed, and end-to-end forearm arteriovenous fistulae are prohibited in patients with positive forearm ALLEN tests. In addition, the following cases should be carefully selected
(1) The patient is expected to have a short survival time.
(2) Patients with unstable cardiovascular status, uncontrolled heart failure or hypotension
(3) Infection at the surgical site. Consider surgery after establishing infection control
(4) Pacemaker catheter in the ipsilateral subclavian vein.
When to start considering an arteriovenous endovascular fistula? In China, due to the lack of awareness of patients about their disease and the lack of awareness among health care providers, many uremic patients tend to consider establishing vascular access only when they need to start dialysis, and this approach causes many problems for uremic patients. Since it takes some time for the arteriovenous endovascular fistula to mature, during this time of maturation, patients must use central venous placement or direct arteriovenous puncture, which invariably increases the suffering of uremic patients.
For this reason, we recommend that patients should consider action endovenous fistuloplasty 3-6 months before the expected start of dialysis, especially in elderly patients, diabetic patients, patients with systemic lupus erythematosus, and patients with comorbid other organ insufficiencies, who should undergo early vascular assessment and preparation and start considering vascular access early.
Preoperative vascular assessment and preparation: for the action of intravenous fistula selected vessels, should meet certain conditions, generally speaking, superficial veins ≥ 2.5 mm in diameter is appropriate, veins are too thin, maturation time is too long and inappropriate, more importantly, the blood flow required for dialysis is not reached, postoperative easy to narrow, occlusion, resulting in thrombosis, etc., while the selected arterial diameter is generally ≥ 2.0 mm is appropriate, arteries are too small blood flow Not enough blood flow to meet the requirements. Whether it is an artery or a vein, serious lesions in the adjacent vessels should be excluded to ensure the stability of blood circulation in the postoperative site and the distal limb as much as possible.
In addition, for patients who intend to operate intravenous fistula, we should try to avoid puncturing the superficial veins or arteries to be operated on, thus causing unnecessary damage to the vessels; for patients with small superficial veins, preoperative vascular exercises should be strengthened (tying a tourniquet on the upper arm, doing fist clenching or ball pinching exercises for 1-2 minutes each time, more than 10 times a day), in order to meet the requirements of surgery.
The principle of selecting vessels for surgery: three first and three later, that is, upper limb first, then lower limb; distal end first, then proximal end; non-dominant side first, then dominant side; the corresponding selectable vessels include: forearm wrist radial artery – cephalic vein; wrist ulnar artery – noble vein, noble vein – radial artery, elbow cephalic vein, noble vein or elbow median vein – brachial artery or radial artery or ulnar artery of its branch, lower limb saphenous vein – saphenous vein. dorsalis pedis artery, saphenous vein – anterior tibial or posterior tibial artery, etc. The most commonly used is the radial artery – cephalic vein in the forearm wrist. There are generally three types of anastomoses, namely lateral anastomoses, end-lateral anastomoses, and end-to-end anastomoses.
The following is an example of an end-lateral anastomosis of the radial artery – cephalic vein in the left wrist.
1, The patient is in supine position, the left upper limb is abducted on the operating table, the marker marks the alignment of the cephalic vein, and the sterile towel is routinely disinfected (note the scope of disinfection, the limb below 10 cm above the elbow joint, including the palm of the hand, the back of the hand and the finger suture).
2.Local anesthesia: 1% lidocaine in the expected surgical incision site to do superficial local anesthesia, pay attention to the radial artery position is deeper than the vein, should be additional local anesthetic next to its fluctuation site.
3, incision: 2-3cm from the wrist (can be adjusted according to the specific vascular site) radial side to make a transverse incision, the length of the incision is generally about 2-3cm (can fully expose the artery and vein is appropriate).
4.Separate the veins: cut the skin and subcutaneous layer by layer, separate the cephalic vein about 2-3cm with vascular forceps, and ligate the cephalic vein genus branch with line 0. At this time, pay attention not to ligate too close to the vein so as not to cause the main trunk stenosis. Lift the cephalic vein and wear a thin rubber band for backup.
5, in the cephalic vein medially according to the radial artery pulsation to determine its position, vascular clamp to separate the fascia and ligament, fully expose the radial artery, open the arterial sheath, pick up the radial artery to wear a fine rubber band to do traction, ligate the radial artery branches (at this time should pay special attention to the radial artery deep surface of the fine branches, easy to be tugged and torn, resulting in bleeding, affecting the surgical field), separate the accompanying veins, free the radial artery about 1-2cm.
6.Ligation of the vein: rubber band lift the head vein, pay attention not to twist, proximal end on the vascular clamp, distal end after disconnection ligation. Cut the cephalic vein obliquely at the distal end, with the oblique surface relative to the lateral side of the artery and parallel to its course. The vascular clamp is released and 10-15 ml of heparin saline is injected into the lumen of the cephalic vein to flush the residual blood to avoid thrombosis. Clamp the proximal end of the vessel.
7.Treat the artery: lift the radial artery control skin band, clip the vascular clamp at both proximal and distal ends, fix both sides of the skin band with vascular clamp, pay attention to the tension is not easy to be too large, so as not to cause vasospasm. Use the surgical sharp blade to pick a break in the radial artery on the lateral side, ophthalmic scissors to cut a longitudinal incision of about 6-8 mm along the break in the radial artery, and heparin saline to flush the vascular cavity.
8.Anastomosis: After checking that the vessel is not twisted, a 7-0 atraumatic vascular suture is passed through the proximal end of the radial artery incision (from the lateral wall into the medial wall), and then from the obtuse angle of the cephalic vein dissection (proximal end) (from the medial wall of the vein into the lateral wall), and a knot is tied to fix the proximal end, paying attention to at least four knots. At the acute angle (distal end), another suture is passed through as a traction line for the vein. The traction line is lifted by the assistant to fully expose the inferior lateral wall of the radial artery incision. A continuous external suture is made with one of the sutures just after the knot is tied, taking care to pass through the outer membrane of the artery and out of the inner membrane, then through the inner membrane of the vein and out of the outer membrane. After suturing to the distal end of the anastomosis, a traction line is threaded through the distal end of the arteriotomy and secured with at least 4 knots.
Then one section is tied with the assistant’s traction line and the other end is continued to the proximal end with successive sutures to the proximal end and then tied with the stump of the original suture, at least 6 knots are tied. If the lumen of the vein is thin, interrupted sutures can be used in the upper wall to avoid narrowing of the anastomosis. All suture stumps are interrupted and the suture is completed. The vascular lumen should be moistened by intermittent flushing with a noninvasive needle injected with heparin saline during the suturing process.
Before suturing the last stitch, the vascular lumen is again flushed with a low concentration of heparin saline and the vascular lumen is filled and then the last stitch is sutured and knotted. The assistant lifts the radial artery control skin band to block the radial artery blood flow. After the sutures are completed, the vascular anastomosis is positioned and the venous clamp is released first, followed by the arterial clamp. At this point, observe the vascular anastomosis for blood leakage and blood flow patency. If there is a small amount of blood leakage, the bleeding can be stopped after gentle compression with a wet gauze block. If there is a large amount of blood leakage, find the point of leakage and close it with a single stitch. After opening the blood flow, in general, more obvious vascular tremor can be felt in the venous segment.
9.Check again the anastomosis for distortion of the fistula, tension at the anastomosis, stenosis at the vein end, and narrowing.
10, mattress suture skin, external sterile gauze, at this time pay attention to the tape do not wrap too tightly, so as not to affect the blood return.
Postoperative treatment.
1.Anticoagulant use: If the patient has a hypercoagulable state and there is no postoperative bleeding, oral enteric aspirin tablets, clopidogrel, etc. can be given.
2, postoperative observation of the surgical wound for blood seepage, less blood seepage can be light pressure to stop bleeding, but pay attention to keep the presence of vascular tremor when compression; if there is more blood seepage need to contact the doctor to open the wound to stop bleeding.
3, functional examination: postoperative veins can be palpable tremor and hear vascular murmur. Early postoperative examination should be performed several times for early detection of thrombosis and timely treatment.
4.Appropriate elevation of the limb on the side of the endovascular surgery can reduce limb edema.
5, a week after surgery to keep the surgical wound excipient dry, such as excipient contamination or oozing wet, need to be replaced in a timely manner, such as dry can be changed every 2-3 days once, 10-14 days to remove the stitches, pay attention to the dressing dressing without pressure.
6, pay attention to body posture and cuff tightness, avoid pressure on the limb of the internal fistula side.
7.Avoid transfusion, blood transfusion and blood test on the limb of the internal fistula side after surgery.
8.No blood pressure measurement on the operated side and no tourniquet on the upper limb of the operated side within 2 weeks after surgery.
9. 24 hours after surgery, the operated side can make fist and wrist movements to promote blood circulation and prevent thrombosis.
10. One week after surgery, start functional exercise by squeezing a leather ball or rubber band several times a day for 3-5 minutes each time to promote the maturation of internal fistula.
11, hemodialysis within a week after surgery, the dose of heparin needs to be adjusted, and the amount of heparin should be reduced appropriately according to the wound situation to avoid serious bleeding from the wound.
12.The maturation period of endovascular fistula is usually 4-12 weeks, and it is not advisable to use endovascular fistula too early to avoid adverse consequences such as endovascular hematoma and endovascular occlusion. During such period, the patient may temporarily establish temporary vascular access in case of emergency hemodialysis.
Maintenance of arteriovenous endovascular fistula during routine use
1, after each dialysis, gauze roll compression to stop bleeding for 15-20 minutes, if no blood is seen at the puncture site, the compression can be released; if there is a little blood leakage, reduce the compression, continue compression for 30 minutes to an hour or even continue to extend depending on the blood leakage. For patients who are prone to hypotension, the compression should not be too strong and the compression time should not exceed 20 minutes.
2. 24 hours after the end of dialysis, hot compresses can be applied to the punctured vessels and softening drugs can be used to protect the internal fistula vessels.
3, the internal fistula site can wear wrist guards to protect the internal fistula from being bumped, as well as to prevent excessive expansion of the internal fistula vessels.
4, keep the arm on the side of the internal fistula clean, when the internal fistula puncture itchy, you can not scratch directly with your hands to avoid skin breakage infection.
5, daily self-examination of the fistula See: to see whether the fistula vessels have collapsed; listen: listen to the stethoscope at the fistula there is no murmur; touch: touch the fistula there is no tremor; sense: feel the fistula vessels have a relatively strong pain.
6, the fistula side of the limb can not lift heavy objects, can not wear tight clothing, the wrist can not wear all objects; lying down can not compress the fistula side of the limb, the fistula side of the limb can not pillow pad under the head.
7, can not be within the fistula side of the limb to measure blood pressure, infusion, blood transfusion, etc..
8, the use of internal fistula during hemodialysis, puncture should be used rope ladder puncture method, as far as possible to avoid the formation of aneurysms.
In addition, for those who have poor vascular conditions and cannot perform autologous arteriovenous endovascular fistuloplasty, autologous graft vessels or artificial vessels can be used instead (as this procedure is not carried out in large numbers, it will not be introduced for the time being), in short, an ideal vascular access requires the joint efforts of doctors, nurses and patients, hoping that uremic patients can obtain a vascular access that best suits them.