NKF K/DOQI GUIDELINES 2000
 
 

GUIDELINES FOR VASCULAR ACCESS

IV. Management of Complications: When to Intervene

GUIDELINE 16

Managing Potential Ischemia in a Limb Bearing an AV Access

All patients, particularly those in high-risk groups, should be monitored for the development of limb ischemia following AV access construction.

A. Patients in high-risk groups (diabetic, elderly, those with multiple access attempts in an extremity) should be monitored closely for the first 24 hours postoperatively. Monitoring should include: (Opinion)

1. Subjective assessment of complaints, including sensations of coldness, numbness, tingling, and impairment of motor function (not limited by postoperative pain)

2. Objective assessment of skin temperature, gross sensation, and movement and distal arterial pulses in comparison to the contralateral side

3. Teaching patients to immediately report any coldness, loss of motion, or significant reduction in sensation

B. Patients with an established fistula should be assessed monthly. The following are recommended as part of this assessment: (Opinion)

1. Obtaining an interval history of increased distal coldness or distal pain during dialysis, decreased sensation, weakness or other reduction in function, or skin changes

2. Confirming any abnormalities by physical examination

Patients with new findings suggestive of ischemia (A.3 above) should be referred to a vascular access surgeon emergently. Reduced skin temperature, as an isolated finding, requires follow-up observation but no emergent intervention. (Opinion)

Rationale Patients with diabetes and/or those with abnormal arterial supply caused by prior vascular access, vascular anomalies, and/or atherosclerotic disease are at greatest risk for ischemia. Limb ischemia distal to an AV access can occur at any time, from a few hours to months, following access construction. Severe ischemia can cause irreparable injury to nerves within hours and must be considered a surgical emergency. Mild ischemia–manifested by subjective coldness and paresthesias and objective reduction in skin temperature but with no loss of sensation or motion–is common and generally improves with time. Patients with mild ischemia should undergo symptom-specific therapy (eg, wearing a glove) and frequent physical examination, with special attention to subtle neurologic changes and muscle wasting.157 Failure to improve may require surgical intervention with banding or access correction or ligation.

GUIDELINE 17

When to Intervene–Dialysis AV Grafts for Venous Stenosis, Infection, Graft Degeneration, and Pseudoaneurysm Formation

Appropriate intervention in AV grafts should be initiated upon identification of:

A. Hemodynamically significant stenosis (see Guideline 10: Monitoring Dialysis Grafts for Stenosis) (Evidence)

B. Infection–an infected graft should be treated surgically (Evidence)

C. Graft degeneration and pseudoaneurysm formation–grafts should be surgically revised when:

1. Severe degenerative changes of the graft or overlying skin are present. (Opinion)

2. Skin above the graft is compromised. (Opinion)

3. There is a risk of graft rupture due to poor eschar formation or there is evidence of spontaneous bleeding. (Opinion)

4. Limited puncture sites are available due to the presence of a large (or multiple) pseudoaneurysm(s) (see Guideline 27: Treatment of Pseudoaneurysm of Dialysis AV Grafts). (Opinion)

Rationale Hemodynamically significant stenoses. Hemodynamically significant stenosis is defined as a >50% reduction of normal vessel diameter (graft or draining venous system) accompanied by a hemodynamic, functional, or clinical abnormality, such as: elevated static or dynamic pressures, decreased blood flow, elevated access recirculation, a swollen extremity, or unexplained reduction in Kt/V (see Guideline 10: Monitoring Dialysis AV Grafts for Stenosis, and Guideline 11: Monitoring Primary AV Fistulae for Stenosis).

Venous stenosis increases the risk of thrombosis.117,119 Physiologically, venous stenosis increases resistance to blood flow, which in turn results in increased venous pressure, decreased blood flow and ultimately, thrombosis.9,119 When examined angiographically, more than 90% of thrombosed grafts are associated with venous stenosis.158-163 Moreover, the presence of venous stenosis reduces the efficiency of the dialysis treatment.113,128 Stenosis can and should be detected prospectively to allow swift, successful treatment (see Guideline 11: Monitoring Primary AV Fistulae for Stenosis, and Guideline 12: Recirculation Methodology, Limits, Evaluation, and Follow-Up).

Therapeutic interventions for hemodynamically significant stenoses reduce the rate of thrombosis and graft loss and prolong the average use-life of the access.9,30,109,119,164,165 The literature suggests that the long-term patency of AV grafts is improved if stenoses are treated prior to thrombus formation as opposed to undertaking angioplasty or surgical revision (with their respective needs for thrombolysis or thrombectomy) after thrombus occlusion of the access has occurred. Prospective intervention currently is not warranted for anatomical stenoses found in AV grafts and draining veins that are not associated with a hemodynamic, functional, or clinical abnormality (such as elevated static or dynamic pressures); decreased blood flow; elevated access recirculation; or a swollen extremity.9,103,119 Prospective studies correcting 50% stenoses not associated with a hemodynamic, functional, or clinical abnormality have not been performed. Until these studies are performed, there is no convincing evidence that correction of asymptomatic 50% stenosis will decrease thrombosis.

When treatment of a thrombosed graft does not address the presence of an underlying venous stenosis, there is a 90% or greater chance that the treatment will be inadequate and will result in rapid re-thrombosis.163 Stenosis detected prior to access thrombosis is more responsive to therapy than stenoses detected postthrombosis (see Guideline 19: Treatment of Stenosis without Thrombosis in Dialysis AV Grafts and Primary AV Fistulae, and Guideline 21: Treatment of Thrombosis and Associated Stenosis in Dialysis AV Grafts). In a retrospective analysis, when thrombosis was treated with thrombolysis and PTA, 50% of grafts were patent 4 weeks later. In contrast, when the graft was still patent at the time of angioplasty, 50% of the grafts remained patent for 24 to 28 weeks.166 Beathard103 reported a 78.9% patency at 3 months for stenotic grafts treated prior to thrombus formation. In contrast, the primary patency rate for grafts averaged 40% when stenoses are corrected postthrombosis.103,107,167

Arterial stenosis associated with diminished access inflow, characterized by elevated negative pressure, should be evaluated and corrected (see Guideline 19: Treatment of Stenosis without Thrombosis in Dialysis AV Grafts and Primary AV Fistulae).

Infection. When infected, a dialysis AV graft should be treated surgically. An untreated access infection may lead to bacteremia, sepsis, hemorrhage, and death.14,16,38,168 Surgical exploration and removal of any infected graft or graft segment is necessary for resolution of the infection because the graft material acts as a foreign body unless eliminated13,14,16,38,53,169 (see Guideline 24: Treatment of Infection of Dialysis AV Grafts).

Graft degeneration and pseudoaneurysm formation. Degenerative changes that occur within a graft and the overlying skin, including pseudoaneurysm formation with progressive enlargement, can eventually compromise circulation to the skin above the graft. This can lead to incomplete hemostasis upon needle withdrawal and ultimately to graft rupture. Thus, these degenerative changes can lead to severe hemorrhage and potentially to exsanguination and death. The Work Group believes that large pseudoaneurysms can also prevent access to the adjacent areas of the graft for needle placement, thereby limiting potential puncture sites.

GUIDELINE 18

When to Intervene–Primary AV Fistulae

Appropriate intervention in primary AV fistulae should be initiated upon identification of:

A. Inadequate flow to support the prescribed dialysis blood flow (Evidence/Opinion)

B. Hemodynamically significant venous stenosis (Evidence)

C. Aneurysm formation–a primary AV fistula should be revised when an aneurysm develops if: (Opinion)

1. The skin overlying the fistula is compromised.

2. There is a risk of fistula rupture.

3. Available puncture sites are limited.

Rationale Inadequate flow to support the prescribed dialysis blood flow. A primary AV fistula should be revised when its blood flow is inadequate to sustain adequate dialysis blood flow, as manifested by the inability to achieve the prescribed Kt/V within a reasonable dialysis duration. Low access blood flow has a major effect on the delivery of dialysis–inadequate blood flow may result in inadequate dialysis, thereby increasing patient mortality and morbidity.170,171

For native fistulae, significant stenoses do not always cause elevated dynamic or static pressures. They can result in decreased access flow and elevated recirculation in the absence of elevated dynamic or static pressures (see Guideline 10: Monitoring Dialysis AV Grafts for Stenosis, and Guideline 11: Monitoring Primary AV Fistulae for Stenosis).

Hemodynamically significant venous stenosis. In a primary AV fistula, the major physiologic effect of stenosis is low blood flow, which results in inefficient dialysis (see above). Low blood flow also increases the risk of thrombosis.109

Treatment of hemodynamically significant venous stenosis prolongs the use-life of the fistula.109,112,119,165

Aneurysm formation. Progressive enlargement of an aneurysm can eventually compromise the skin above the graft, leading to possible rupture. This can result in hemorrhage, exsanguination, and death. In the Work Group’s opinion, large aneurysms can prevent access to the adjacent fistula for needle placement, thereby limiting potential puncture sites.

 

 

 

© 2001 National Kidney Foundation, Inc

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