GUIDELINES [ back to index ]

3. Clinical evaluation of access site

 

  1. Medical history/concomitant diseases
  2. Previous venous cannulation
  3. Previous and current central venous catheters
  4. Cardiac/vascular diseases
  5. Stroke and other neurological diseases
  6. Severe joint disease or vasculitis
  7. Local infection
  8. Arm swelling
  9. Presence of collateral veins
  10. Scars
  11. Generalised dermatological problems
  12. Thickness of subcutaneous fat
  13. Palpation of veins
  14. Palpation of arterial pulses
  15. The Allen-test
  16. Blood pressure difference
  17. Auscultation of arteries


*1  Medical history/concomitant diseases

• Medical history and concomitant diseases have a strong impact on the choice of possible access sites. Vascular access as a matter of principle should be created as distally as possible in order to preserve proximal sites for later.

• Female gender and old age as risk factors influencing fistula creation remain controversial.  Elderly and diabetic patients have reduced quality of vessels needed for successful access creation 1. In diabetic patients, some authors therefore recommend elbow A/V fistulas instead of wrist fistulas 2 3. This policy is reasonable in patients with reduced life expectancy irrespective of underlying diagnosis, in whom a single successful access procedure may suffice for the rest of their lives. In younger patients with reasonable life expectancy but with sub-optimal veins and arteries, however, every effort should be made to create a peripheral A/V fistula at the wrist or at the forearm, accepting the increased risk of surgical revision or radiological intervention  later.

• Diabetic patients often display medial calcification of their peripheral arteries (especially radial and ulnar arteries). Medial calcification will hinder the maturation process of the A/V fistula by preventing the natural dilatation of the feeding artery and the subsequent increase in arterial flow. Preoperative X-ray of the hand can be performed to look for medial sclerosis. When severe medial sclerosis is present some surgeons avoid radiocephalic A/V fistula creation in favour of an elbow A/V fistula 4. However, functional distal A/V fistulas have been reported in the presence of calcification although there is a higher risk of failure5. The  decision of access site has to be made by an experienced access surgeon on an individual basis in each diabetic patient.

• Access surgery is also difficult in small women, children, elderly or obese patients, in patients with breast and oto-rhino-laryngeal cancers, after solid organ transplantation and long-term steroid therapy, due to size, location and damage of vessels. Venography and ultrasonography are of great value in localising  suitable veins in such patients 6.

• Cardiac surgery, or clavicular fracture increases the risk for central venous stenosis or occlusion.

 

*2  Previous venous cannulation

• Venous system cannulation, i.v. drug abuse , intensive intravenous  therapy and numerous venous blood sampling often destroy the superficial venous system and in such patients, radiological and ultrasonographic examination has to be done carefully to find a suitable vein for access creation.

 

*3  Previous and current central venous catheters

• Central venous catheterisation  for dialysis, placement of a pacemaker 7 or  port for chemotherapy, may cause central venous stenosis or thrombosis, often indicated by clinically obvious venous collateralisation over the shoulder and chest. Thus, creation of an A/V fistula in the upper limb may be impaired, since venous stenosis will become symptomatic   once there is increased venous blood flow from the fistula. This condition usually results in a painful swelling of the whole arm 8.

 

*4  Cardiac / Vascular diseases

• Myocardial infarction, coronary artery bypass grafts, peripheral bypass, stroke or amputation suggest generalised arterial disease. Thus careful clinical, ultrasonographic, and angiographic  investigation is mandatory, particularly to assess the quality of the arterial tree 6 9 10.

• As stated by Sidawy et al.. “contrast arteriography remains the gold standard for the evaluation of a suspected inflow stenosis or occlusion. When in doubt regarding the adequacy of the donor artery or the runoff, it is advisable to obtain an arteriogram that shows the entire arterial system from the origin of the subclavian to the distal branches. Magnetic resonance angiography can also be used for the same purpose” 11.

 

*5  Stroke and other neurological diseases

• Hemiparesis is thought to cause reduced arterial and venous blood flow rates due to immobility. In most of these patients, the paralysed arm is selected for access creation despite comparatively less suitable vessels in the other upper limb, because the other arm may be used to support walking with crutches and thus the access vein might be exposed to external compression and damage.

• In addition, in selecting the paralysed arm, the healthy arm can be used during the period  of haemodialysis, and particularly for puncture site compression after completion of dialysis.

• In a severely disabled limb, however, access creation and cannulation may be difficult or even impossible if severe contracture  occurs.

 

*6  Severe joint disease or vasculitis

• Patients suffering from severe joint disease and vasculitis have often undergone long-term steroid therapy, which often results in vascular complications such as increased arterial wall thickness, arterial stiffness and loss of distensibility. Steroid-induced skin atrophy and immunosuppression enhance the risk for postoperative infectious complications.

 

*7  Local infection

• Vascular access should be placed only after resolution of local or systemic infection.

 

*8  Arm swelling

• Inadequate venous drainage may be indicated by swelling of one arm compared to the other, and prominent collateral veins around the shoulder. Such signs are indications for venography. If the underlying anatomic defect cannot be corrected, the limb must not be used for access creation, as an already symptomatic stenosis will become even more so 8.

• In cases of bilateral obstruction, the central venous stenosis or occlusion may be treated by angioplasty or surgical bypass, which should be performed simultaneously to or soon after creation of the A/V fistula. Long-term success is poor.

 

*9  Presence of collateral veins

• Special attention has to be paid to venous collaterals of the upper arm and shoulder suggesting central venous stenosis. 

• The finding of venous collaterals is an indication for  bilateral  imaging by MRA or venography, using CO2 or gadolinium in cases of iodine sensitivity.

• Depending on the character of the venous narrowing, an A/V fistula can, nevertheless, be created in  some of these patients. With a functioning A/V fistula, interventional procedures such as angioplasty and/or stent insertion can be done much more proficiently and successfully. In some of these patients venous hypertension after creation of the A/V access will be so mild that a "wait and see“ policy may be instituted. Such decisions should be based on the investigator’s experience and tailored to the individual patient.

 

*10 Scars

• Scars in the arm or neck will reveal previous operations, traumatic events and central venous catheterisations. A combination of typical scars and inflammatory signs may be found in a drug addict.

 

*11  Generalised dermatological problems

• In most patients with generalised dermatological problems, a vascular access can be created using supportive anti-inflammatory therapy recommended by dermatologists.

 

*12  Thickness of subcutaneous fat

• Obesity can prevent effective palpation of the forearm and upper arm veins. On the other hand, an  absent subcutaneous fatty layer may increase the risk of skin necrosis, especially when the insertion of graft material is necessary .

• Subcutaneous fat usually preserves superficial veins from venipuncture and cannulation. These veins are often of very good quality but frequently will necessitate transposition into a more superficial location after fistula creation.

 

*13  Palpation of veins

• Examination should take place in a warm room. A  tourniquet should be placed around the upper arm or a blood pressure cuff inflated to 40 mm Hg in  order to produce sufficient venous distension. For examination of the proximal upper arm veins a  band tourniquet close to the axilla can be used. The anatomical course of the forearm cephalic and basilic veins should then be inspected and palpated. The veins should be distensible (up to 2-3 mm), patent and without stenosis up to the elbow in order to provide a good A/V fistula. By light percussion of the vein at the wrist, a transmitted pulse wave should be felt in the vein at the elbow and vice versa, proving the patency of the vein.

• In addition to the forearm veins, the great veins of the upper arm should be evaluated carefully. By exerting different pressures with a blood pressure cuff, diameter, continuity, distensibility and compressibility of the veins are controlled. In venous thrombosis, these characteristic clinical signs are usually absent.

• Venous imaging by either colour-coded duplex-ultrasound, venography or MRI is indicated when no vein clinically appears to be usable in both forearms. Venography or MRI should be performed, when a central venous obstruction is suspected (see *8 and *9 )

 

*14  Palpation of arterial pulses

• Palpation characterises the pulses of the brachial, radial and ulnar artery, giving initial information on the quality of the arterial tree. The pulse of the brachial artery is palpated at the medial side of the elbow, the radial pulse 2 cm proximal of the proc. stylodius radii and the ulnar pulse 2 cm proximal of the proc. styloidius ulnae, to check for any obvious signs of calcification and atherosclerosis impairing the arterial inflow. The pulses are graded as “normal”, “diminished” and “absent” 11 and compared with the contralateral limb.

 

*15  The Allen-Test

• The Allen test is a very subjective assessment of distal hand circulation with variable outcome. Its value in the assessment for A/V fistula placement remains controversial and of limited value (see appendix for details).

 

*16  Blood pressure difference

• Systolic and diastolic blood pressures should be measured in both arms according to the Riva-Rocci method, in the supine position. An index of the systolic blood pressure of the ipsilateral arm with the systolic blood pressure of the contralateral arm is calculated:

AAI (arm/arm index) =    

systolic blood pressure projected fistula arm systolic blood pressure contralateral arm

 

• Significant proximal arterial disease is likely with an AAI < 0.90. There should be a blood pressure difference of less than 20 mm Hg in the upper limb selected for A/V fistula creation, compared to the contralateral limb. For creating an A/V fistula, a difference in blood pressure below 20 mm Hg is chosen as an non invasive criterion for the selection of upper extremity arterias 12.

 

 

*17  Auscultation of arteries

• In presence of an arterial stenosis, auscultation along the axillary and subclavian artery can reveal a high-frequency bruit.

More detailed information on the quality of the arterial system is provided by duplex scanning 6, which is highly recommended and is evidence based.