maintenance of vascular access

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MAINTENANCE OF HEMODIALYSIS AVF:

MAINTENANCE OF HEMODIALYSIS AVF By: Sherif Mohi El Din Resident of Vascular Surgery El-Sahel Teaching Hospital

Introduction :

Introduction patients on hemodialysis outnumber those of peritoneal dialysis or transplantation

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So the CREATION and MAINTNANCE of vascular access foe aemodialysis is crucial

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Definitions Predictors Strategies to optimize AVF maturation Treatment of non maturing AVF Outcomes Arteriovenous Fistula (AVF) Maturation

Slide5:

Defining AVF Maturation Broad Definitions “…... A serious of processes that begins with the surgical creation of an AVF and ends with it’s successful and reproducible canulation to achieve effective hemodialysis…..” Saad.Vascular 2010

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Specific Definitions “….Has a discerinble margins ,measure about 6 mm in diameter or greater And 6 mm or less deep from the skin surface and have a blood flow more than 600 mm/min….” NKFLKDOQI Guidelines 2006 “....the ability to use the fistula for dialysis within 2 needles and maintain a dialysis machine flow rate optimal for dialysis more than 300 mm/min during 8 dialysis sessions Dialysis Access Consortium JAMA 2008

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AVF Maturation Reported maturation failure rates are high -18-53 % ( Allon M . Kidney Int 2002 ) -59.5 % ( Dember L.JAMA 2008 ) Maturation failure rates are increasing ( Petal S. J of Vasular Surgery 2008)

Factors Associated With AVF Maturation:

Factors Associated With AVF Maturation

Factor Associated With AVF Maturation:

Factor Associated With AVF Maturation Clinical factors Pathological factors Pre-operative hemodynamic factors Intra-operative factors Post-operative hemodynamic factors

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Biology of AVF Maturation • Fistula creation : AV anatomosis blood flow shear stress Shear Stress = 4nQ/ pr • Vascular response : • shear stress to original level by vascular diameter Dilatation • High shear stress venous remodling Endothelial cells secrete NO, prostacyclin, other mediators Arterial vasodilation Venous vasodilation Medial hypertrophy

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Timing of AVF Maturation • Increase in AVF blood flow and diameter occur very early after AVF construction ( ( Robbin M. Radiology 2002; Lin SL. Am J Nephrol 1998 ) • Signs of successful maturation should be evident by 4 weeks post-op ( Robbin M. Radiology 2002 ) • AVF that fail to mature by 6-8 weeks do not mature ( Asif A. Clin J Am Soc Nephrol 2006 )

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• Physical exam has an accuracy of 80% in predicting maturation ( Robbin M. Radiology 2002) • Physical exam needs to be performed at 4 weeks ( FISTULA FIRST ) to 6 weeks ( NKF-KDOQI Guidelines 2006 ) to assess for presence and cause of non maturation Physical Exam of AVF

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Normal Mature AVF – Easily compressible – Soft pulse that quickly augments with AVF compression – Prominent thrill at the anastomosis during systole and diastole, thrill often extends over long segment of AVF

Abnormalities in the Physical Exam:

Abnormalities in the Physical Exam • Visible superficial branches • Thrill that persists despite AVF occlusion • Enlarging segment near the anastomosis

:

Abnormalities in the Physical Exam • Weak pulse and weak thrill • Strong, abrupt pulse. Thrill absent or limited to systole. • Bounding pulse at the anastomosis. Pulse disappears within 5 cm

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so I have to

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1-Respect The Veins

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2-Proper creation C ompressible C aliber C ontinous C annulable C an empty on limb elevation

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3-Basic fistula care

:

The rule of 6 6 mm diameter or more 6 mm from the skin 600 ml/min blood flow rate or more 4-Assist maturation Perfect mature AVF

5-Careful canulation:

5-Careful canulation Rope ladder buttonhole

6-Monitoring &Survellance:

6 -Monitoring & S urvellance

Dealing with Dysfunctional AVF:

Dealing with Dysfunctional AVF Failed AVF………………………Failing AVF

Failing AVF:

Failing AVF . Is defined as one with more than 50% reduction in the normal vessel caliber associated with hemodynamic, functional, or clinical abnormality .

Failed AVF:

Failed AVF Failure of maturation and use from the start Severe stenosis over time hindering any use,up to complete occlusion by thrombosis on top of significant stenosis

What to do???:

What to do???

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In near past • Fistula failure = forget about it totally & create a new one • Available accesses become exhausted over time • No available safe access for hemodialysis . • No available access for hemodialysis. • !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! .

Now:

• As patients survive longer on dialysis , fistula salvag with preservation of other access sites become more important and more appealing than doing a new one. 10 Now

What to do???:

What to do??? Surgical option Endovascular option

Surgical option:

Surgical option Venous bypass Surgical thrombectomy

Why endovascular???:

Why endovascular??? Minimally invasive No need to put double lumen catheter It can be repeated. The fistula can be used the 2 nd day

Exclusion criteria:

Exclusion criteria Infection Systemic low flow state

Indications for interventions:

Indications for interventions 1-Documentation of clinical abnormality : Withdrawal of blood clots during dialysis. Difficult cannulation . Decreased pump flow . Under-dialysis . Decreased or absent thrill and increased pulsatility 2-Doumentation of stenosis by duplex 3-Recently failed AVF

Duplex criteria for significant AVF stenosis:

Duplex criteria for significant AVF stenosis Stenosis severity more than 50% PSV more than 375 cm/sec Access blood flow less than 300ml/min PSVR

Parameters needed to put a proper plan for intervention?????:

Parameters needed to put a proper plan for intervention????? Exact site of anastmosis Severity of each stenosis Length of each stenosis Caliber of the vessel proximal and distal to anastomosis PSVR flow rate Suitable puncture site for endovascular intervention Contribution of radial and ulnar arteries in hand circulation

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You have to know 4 points 1-Get a vascular access 2-Do&interpretate angiogram 3-Crossing the lesion 4-Dilate it

What are the best access for intervention????:

What are the best access for intervention???? BRACHIAL VENOUS RADIAL

Trans-radial approach:

Trans-radial approach

Advantages of Transradial approach:

Advantages of Transradial approach Can treat lesions in both arterial and venous sides wherever it’s site Sheath is away from the fistula No acute manipulation SO better wire movement Compression doesnot impede fistula flow Puncture site complications are better than brachial artery Linda lee,et al J vascular surgery 2014

Slide41:

Linda lee,et al J vascular surgery 2014

Angiogram:

Angiogram Linda lee,et al J vascular surgery 2014

Crossing the lesion:

Crossing the lesion

Dilating the lesion:

Dilating the lesion Longer duration Higher pressure Change the position External digital compression Shorter balloon Non compliant balloon Cutting balloon Larger diameter ballon

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Anatomical Derangements Responsible for AVF Non-maturation Number of Patients 119 141 • Accessory veins 3 % 14% • Arterial inflow stenosis 5 % 6% • Arterial anastomotic stenosis 47% 31% • Juxta -anastomotic venous stenosis 64 % 65% • Venous stenosis in outflow tract 59 % 50% • Central venous stenosis 8 % 4% • Deep or excessively tortuous AVF 5 % Multiple derangements 71 % 46% Nassar GM. Clin J Am Soc Nephrol 2006 Han M. Clin Radiol 2013

Slide46:

Treatment Results (Meta-analysis ) • 47% increase in maturation when primary failing AVFs were treated early • 86% of treated patients (range, 74%-98%) were able to use their AVF at least once for hemodialysis after secondary intervention in non-maturing AVF • Complications (8 articles, 508 patients ) – 47 (9.3%) patients suffered complications • 28 (5.5%) hematoma • 11 (2.2%) venous rupture • 5 (1%) ischemic steal • 1 (<1%) pseudoaneurysm Voormolen E. J Vasc Surg 2009

Novel therapy for treating of non mature AVFs:

Novel therapy for treating of non mature AVFs

Slide48:

Far Infrared Therapy May enhance endothelial cell function and blood flow Treatment of AVF with electromagnitic waves for 40 min 3 times weakly increased AVF maturation in 122 in RCT (Lin CC. Am J Kidney Dis 2013

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