Vascular access

Dr. Ayman Sabry Abd El-BadieNephrology specialist

NMGH

Vascular access

Arterio-venous fistula

AVF is a continuous circuit.

starts at the heart and ends at the

heart .

It is not just an anastomosis.

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Types of AVF

(Role of (6

• Wait 6 weeks minimum for maturation to cannulate

• AVF under skin by 6 mm or less

• Diameter of AVF 6 mm or more

• Blood flow 600 ml/min or more

Fistula needles

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Cannulation techniques

Fistula care

• Dialysis access is extremely precious. • Arm veins should be preserved in pre-dialysis patients (no IV cannulae between elbow and wrist). • Needling should only be carried out by a trained operator. • Technique: avoid using the same site repetitively ( l false aneurysm formation). • Never put a tourniquet or BP cuff on a fistula arm. • Do not use a fistula to take blood. • Hypotension (and volume depletion) thrombosis risk.• Hct (too much ESA) predisposes to thrombosis. Keep within recommended guidelines and at the lower end of these, if at risk. • A clotted fistula or graft requires immediate attention (time to de clotting is a major determinant of success)

بالفيستوال العناية بالماء خاصة الفيستوال منطقة وفي عامة للجلد اليومية النظافة

الجلد جفاف يسبب ال حتى الكاوية المواد من الخالي والصابونوتشققه.

ط/ريق عن وذلك مستمرة بصفة تعمل الفيستوال أن من التأكد. وتدفقه الدم بسريان لتحس عليها األخرى اليد وضع

بأي شعورك وعند المميز الفيستوال صوت وسماع مالحظة. الطبيب بإبالغ عليك صوتها في ضعف

أشياء رفع أو حمل في الفيستوال بها التي يدك استخدام/ عدم/ثقيلة.

. الشديدة البرودة أو للحرارة الفيستوال تعرض عدم/ بإتباع الفيستوال بها التي للزراع يوميا خفيفة تمرينات عمل أهمية

األوردة مساعدة منها الغرض التمرينات وهذه الطبيب إرشادات. والنمو التفتح علي

اليد • علي متكأ النوم مثل الفيستوال علي الضغط عدم. الفيستوال بها التي

إعطاء • أو دم عينة أخذ أو الضغط بقياس السماح عدم. الفيستوال بها التي اليد في محاليل

فوق • ضيقة مالبس لبس .عدم الشربات مثل الفيستوالأي • وجود عند فورا الطبيب إبالغ علي الحرص أهمية

: األعراض تلك من الفيستوال مكان حول التهاب أو احمرار العملية مكان من نزيف الفيستوال مكان في و/سريانه الدم بتدفق اإلحساس عدم الفيستوال بها التي لليد باألطراف تنميل أو 0برودة

Fistula assessment

Hear

FeelSee

Outflow assessmentArm elevation test

• when the extremity is elevated , the fistula collapses completely if there is no outflow obstruction.• when the extremity is elevated , the portion of the fistula distal to point of stenosis remains distended, while the proximal portion collapses in the normal fashion.

Palpation (Feel)

-Palpation of the thrill along the course of the vein

Assessment of the inflow of the blood

Assessment of the accessory veins

Augmentation test

Auscultation

Auscultation the bruit along the course of the vein to the heart

Complications of fistulae and grafts • Clotted: No thrill = thrombosis . seek immediate medical opinion. Swift

intervention (within 48h) either via interventional radiology (local thrombolysis), or surgery, may be able to salvage the fistula. The longer the time to intervention, the less likely it is to be successful. There is no clear evidence for anticoagulation use.

• Infection: fistulae rarely become infected beyond a superficial cellulitis. PTFE infection is not uncommon. May be occult, causing weight loss, ESA resistance, and failure to thrive. Antimicrobials rarely successful, and management usually involves surgical removal.

• Aneurysm or pseudoaneurysm formation: may occur at needling sites, especially if sites not rotated. Surgery may be necessary.

• Bleeding from an infected or aneurysmal AVF or graft is a much feared complication (proceeds under arterial pressure!).

Distal ischaemia or steal syndrome: flow through the fistula or graft may compromise distal blood supply. Cold or numb peripheries are common but may l infarction or ischaemic pain. Other features include paraesthesia, cyanosis, loss of distal pulses. Patients often elect to wear a glove on the affected hand. AVF ligation or graft removal may be necessary in severe cases.

• Excess flow

• Extravasation: blood leakage into the soft tissues. Can cause rapid limb swelling, haemodynamic compromise, compartment syndromes, s infection, access thrombosis.

Temporary dialysis catheter

Temporary dialysis catheter - For immediate use; e.g. AKI

- unresolved sepsis .

-Internal jugular, and femoral are possible routes .

-Ideally leave in situ for ≤2 weeks

Temporary catheter

Tunnelled dialysis catheter

• A dual-lumen venous catheter is placed in a central vein (internal jugular or subclavian; femoral less common).

• Available for immediate use and usually left in situ for 1 – 3 months (occasionally longer).

• Blood flows 300 – 450mL/min achievable.

Tunnelled catheter

Malfunction Catheter • malfunction is common. 50% of lines fail within the first year of

insertion. • Catheter malfunction is defined as one of the following:

- Peak blood flow ≤ 200mL/min for 30min in an HD session. - Mean blood flow ≤ 200mL/min for two consecutive HD

sessions. - No flow, unable to initiate HD.

• Malfunction may be positional (usually ≤7 days post-insertion) or mechanical. Mechanical malfunction may be intraluminal (thrombosis), extraluminal (fibrin sheath), or intrinsic to the catheter material/properties.

Primary prevention • Strategies include heparin, rtPA, or trisodium citrate catheter lumen

lock between sessions.

• The PreCLOT trial showed that rtPA for primary prevention of catheter malfunction (1mg/lumen once/week + heparin for the other two sessions) vs standard heparin (5,000U/mL to fill lumen) was associated with significantly less catheter malfunction and bacteraemia, with no increase in bleeding events.

• Trisodium citrate (4, 30, or 46.7%) has also been shown to be more effective than heparin and causes less bleeding, less biofilm formation, and a significant reduction in catheter-related bacteraemia.

• There are no convincing data for low-dose warfarin, ticlopidine, or other antiplatelet agents with respect to primary prevention.

Treatment • Initial attempts to restore flow: flush catheter with 10mL

syringe of saline; reposition patient; reverse lines. • Thrombolytic agents: streptokinase/urokinase have largely

been replaced by rtPA (alteplase, reteplase, tenecteplase). Differing regimens have been studied: ‘ push ’ , short dwell (30 – 60min), long dwell (>2 hours, interdialytic), or infusions. These methods are associated with short-term success of between 40 and 90%, with median patency 14 – 30 days.

• Exchange over guidewire: if previously listed measures unsuccessful, then consider a catheter exchange.

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