Vascular access is the lifeline for maintaining hemodialysis in uremic patients. The timing of vascular access establishment, reasonable procedure, proper perioperative management and close postoperative follow-up are all important factors affecting its patency and patient’s survival quality.
For the selection of the timing of arteriovenous endovascular fistula surgery, the 2010 standard operating protocol for blood purification states that
(1) Patients with chronic renal failure with glomerular filtration rate <25 ml/min or serum creatinine >4 mg/dl (352 μmol/L) should be considered for the establishment of arteriovenous endovascular fistula;
(The 2008 SVS clinical guidelines state that arteriovenous fistulas should be established 6 months before the anticipated dialysis. This allows sufficient time for maturation and for the fistula to be repaired or even redone.
In this article, we will introduce the arteriovenous endovascular fistula (mainly the artificial vascular arteriovenous endovascular fistula) in terms of the timing of the procedure and the selection of the surgical plan.
I. Selection of surgical access for arteriovenous endovascular fistula
The choice of surgical access for arteriovenous endovascular fistula is generally divided into three types.
(1) Temporary vascular access: the time is generally less than 3 months. This includes the placement of central venous catheters through the internal jugular, femoral, and subclavian veins by puncture.
(2) Semi-permanent vascular access: the duration is usually 3 months-12 months. A central venous catheter with CUFF is left in place via a subcutaneous tunnel (including internal jugular, femoral, and subclavian veins).
(3) Long-term vascular access: The duration is usually from 24 months-48 months. Divided into: permanent central venous catheters.
The NKF clinical practice guideline for quality control of renal disease (K/DOQI) suggests that “autologous endovascular fistula is the first choice; second choice is upper extremity artificial endovascular fistula or lower extremity arteriovenous fistula (autologous or artificial); avoid (>10%) permanent central venous catheters.
At the same time, the NKF guidelines state that: the maturation time for a new autologous AVF is at least 1 month; an artificial endovascular fistula is usually available for 2 weeks; for patients who do not have access to an autologous AVF, an artificial endovascular fistula should be established 3 to 6 weeks before starting hemodialysis; the surgeon must establish access before dialysis and provide sufficient time to facilitate fistula maturation, revision, or reoperation when the first procedure fails time.
Domestic data on access selection for arteriovenous endovascular fistulas are: 84.2% for autologous angioplasty, 10.8% for vascular graft endovascular fistulas, and 5% for long-term dialysis vascular access with deep venous catheters (Shanghai, 2007)
Combining the NKF guidelines and the current status of selection in China, we realize that the current domestic arteriovenous endovascular fistula procedure selection can take the US guidelines as a clinical reference and make a specific analysis according to our national conditions, medical insurance, economic status, technical level, dialysis unit situation and other factors in order to meet the demand of blood purification to the maximum extent.
II. Timing of artificial vascular arteriovenous endovascular fistula
For patients who do not have the condition of autologous AVF, artificial vascular arteriovenous endovascular fistula should be considered. For patients with the following conditions, experience suggests to us that autologous vascular AVF may be more difficult and it is recommended that artificial vascular arteriovenous fistula be taken into consideration.
1, poor condition of the superficial autologous veins of both upper extremities, and difficulty in maturing autologous fistula is expected
2. tortuous shape of the autologous veins in both upper extremities, which is expected to be difficult to puncture
3.Superficial veins of both upper extremities are depleted after multiple autologous fistulas
4.Seriously obese patients, the autologous vein is too deep from the body surface
Third, venous protection and assessment of dialysis access
As mentioned earlier, the vascular condition is an important factor in the timing consideration of artificial vascular arteriovenous endovascular fistula procedure selection, which suggests to us that the protection of vascular conditions (mainly veins) is crucial in daily dialysis, pre-surgical preparation and even post-surgical management. The main elements we summarize from our clinical work experience are.
1.Protection of the peripheral veins of the upper arm for the future establishment of permanent vascular access;
2. Whenever possible, hand veins should be preferred over forearm veins for venipuncture and catheterization in CKD patients;
3, Pay special attention to avoid puncturing the cephalic vein on the non-dominant side;
4.When forearm vein must be used, alternate puncture sites should be used to prevent stenosis after repeated puncture of the same site caused by vascular injury;
5.Patients with renal insufficiency should avoid placing PICC before kidney status assessment to protect the central vein;
6, the use of ultrasound examination of the blood vessels of the upper extremity before surgery to clarify the vascular alignment and thickness can increase the success rate of surgery and improve long-term prognosis.
Some ideas and strategies of artificial endovascular fistula surgery
Unlike autologous vascular arteriovenous fistula, the plasticity of the length and angle of the artificial vessel achieves its diversity and plurality in the arteriovenous anastomosis. In summary, there are several key strategies as follows.
1, the arterial anastomosis end of the artificial vessel AVG can be located at the distal end of the limb
2.The radial artery can be pulsed and accessible, and direct vascular access between the radial artery and the anterior elbow vein of the artificial vessel can be established.
3.If the radial artery is inaccessible, a circumferential vascular access from the brachial artery to the anterior elbow vein should be established.
4.The venous outflow tract anastomosis should be avoided across the elbow joint to protect the upper arm veins for future access establishment
5.Pre-operative minimization of relevant endoluminal interventions to avoid damage to the venous outflow tract
V. Selection of artificial vascular arteriovenous endovascular fistula for establishment
For bilateral forearm vein depletion, either “forearm artificial vascular access” or “upper arm vascular access of any type” can be chosen, depending on the availability of veins and the surgeon’s skill. We recommend that physicians offer patients a choice between the two options.
The relevant evidence-based medical evidence suggests that
In a 12-month randomized controlled clinical study, the initial patency rate and second-stage patency rate were significantly higher in the upper arm autologous brachial artery-valvular arteriovenous fistula than in the forearm artificial vascular access group;
2. Both types of procedures had similar long-term patency rates at 12 and 24 months, but autologous vascular access complications were lower (second study);
3. There was no evidence that autologous vascular access to the upper arm was superior to artificial vascular access in reducing complication rates.
VI. Common procedures for artificial endovascular fistula
1.Straight forearm type :
2.Forearm trip type (U type)
3.Upper arm straight type
4.Inguinal trip type or CROSSOVER
VII. Recommended basic principles of operation
1.Avoid crossing the joint as much as possible to avoid fracture when the joint moves;
2.Strict skin disinfection, it is recommended that the artificial blood vessel should not directly contact the skin or surgical gloves during the operation
3.The anastomosis is suitable, or may cause insufficient flow, cardiac failure or distal limb ischemia
4.Anastomosis between the artificial vessel and axillary vein should avoid the position of axillary vein valve;
5.The depth of the artificial blood vessel should be moderate, too deep will affect the postoperative puncture, too shallow may lead to epidermal necrosis or artificial blood vessel infection;
6, the tunneling device through the subcutaneous to try to once a success, so as not to aggravate the postoperative seroma, and should avoid artificial blood vessel distortion, into the angle or pressure.
7, the correct use of the artificial vascular endovascular fistula is also an important factor in determining its patency.
Above, we have introduced the content of the artificial vascular arteriovenous endovascular fistula procedure in terms of surgery timing and surgical procedure selection. In the end, we would like to remind that the most common and important problem of endovascular access is stenosis and thrombosis, which requires us to work not only on surgical access, but also on postoperative access maintenance.