Chap 73-77 Vascular Access Flashcards by Christine Herman

What is the 1-year mortality for patients on HD?

22%

mean life expectancy 5.8y

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What are the SVS guidelines for starting HD?

For using AVF?

Cr clearance <25ml/min

autogenous should mature for 6 months (4-6weeks ok)
prosthetic 3-6weeks
would be constructed before initiation of HD

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Why wait >4-6 months before initiation of HD?

lower risk of death and sepsis compared to <1 month

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Does plavix help keep AVF open?

there is no evidence to support that

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What are catheter options for dialysis?

short term

double lumen, non-tunneled, noncuffed, <6 months)

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What bacteria are associated with catheter infection?

S.Aureus, CONS, enterococcus, pseudomonas

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How do you clinically exam UE for AVF and important hx?

Neuro
derm
CHF, dominance, IV/central lines, trauma
pulses
edema
tourniquet to assess veins for continuity and size
tap
chest wall collaterals

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What are ideal vessel sizes for UE AVF?

How does vein size affect maturation/patency?

artery 2mm
vein 3mm

if 2.5 maturation 90%, 80% 1 year patency

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Why is cephalic better then basilica vein?

easier to access for HD puncture

minimal dissection

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What is the order of forearm AVF?

Snuffbox/posterior radial branch-cephalic
radio-cephalic (Brescia-Cimino-Appel) (if PRB non palpable)
radio-cephalic transposition (if cephalic too far way)
ulnar-cepahlic (if radial not palpable)
Brachial-cephalic forearm looped transposition (if radial/ulnar pulse not palpable but brachial is)
autogenous radial-basilic forearm transposition OR
autogenous ulnar-basilic forearm transposition OR
autogenous brachial-basilic looped transposition (all if cephalic not adequate)

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Once forearm options exhausted what are other options?

can consider prosthetic to exhausted forearm before moving to upper arm. can extend dialysis 1-3 years
6mm PTFE no rings

distal arterial inflow
radial-ac straight
brachial-ac forearm loop

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What are upper arm AVF options?

brachial(or prox radial)-cephalic
autogenous brachial-cepahlic transposition (if cephalic too far away)
autogenous brachial-basilic transposition (if cephalic no good)
brachial-brahcial transposition OR GSV/femoral vein translocation if either vein no good)

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What is femoral vein and SVG latency in UE AVF?

SVG not known, tends not to dilate

femoral vein 94% at 2 years

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What is preferred vein and artery for LE AVF?

What size should anastomosis be?

GSV, femoral artery

4-6mm

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Why are LE AVF bad?

high infection rates, higher likelihood of steal, higher rates of PVD

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What are possible configurations for LE AVF?

autogenous femoral-GSV transposition (loop or straight)
autogenous tibial-GSV direct access
Femoral-femoral transposition
prosthetic femoral artery-femoral vein

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What are possible configurations for body wall AVF?

venous outflow axillary, jugular, common femoral vein
prosthetic ax-ax chest
prosthetic ax-ax chest loop
prosthetic ax-common fem vein chest

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How should grafts be surveilled post-op?

no clear benefit in surveillance
clinical monitoring by skilled personal is adequate
32% reduction in overall cost but mostly in prosthetic
seem more reasonable in prosthetic

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What are clinical signs of distal graft stenosis for autogenous graft?

palpable pulse ar arterial end, failure to collapse with arm elevation, discontinuous bruit, complete access collapse proximally, persistent edema, venous collaterals on ipso chest wall, continued bleeding

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What is static venous pressure?

turn dialysis pump off and equilibrate circuit. venous (efferent) needle pressured is measured. if >50% of MAP considered abnormal or if begins to increase over time

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What three features make maturation more likely?

rule of 6

600ml.min flow

What flow rate is indicative of autogenous graft dysfunction?

< by 25%

What can cause failure of maturation? (4)

too deep (may need to retunnel)
non-ligated side branches
poor venous outflow
(distal stenosis, vein too small)
insuff arterial inflow

What can be done to accelerate maturation?

balloon access maturation (BAM)

2,46, weeks progressively larger balloons

What are AVF complications?

``` thrombosis intimal hyperplasia failure to mature infection seroma pseudoaneurysm aneurysm steal IMN ```

What is most common complication? how to deal with it?

``` thrombosis early and late prosthetic does better then autogenous tpa 2-4mg oen thrombectomy ```

How does intimal hyperplasia cause AVF complications? How to manage?

>90% graft failure venous anastomosis stenosis if >50% should be treated patch, endovascular

what are RF associated with graft failure

age, DM, vein diameter <2mm, CHF, female

What are clinical features favouring use of a prosthetic?

imminent need of HD short life expectancy morbid obeisty unfavorable vascular anatomy

What is the benefit or pre-op non-invasives studies?

no difference in primary patency but lowers initial failure rate and improved primary assisted patency not SVS recommendation

Describe the two stage approach to the brachia-basilic AVF?

incision prox ac and anastomosis once dilates to 6mm, skip or continuous incisions over course of the vein and dissect. either elevate vein or disassemble anastomosis simply elevating makes accessing difficult because courses medially

What nerves runs over basilic vein?

medial antecubital nerve so if elevate vein either transect nerve or transect anastomosis. sensory medial cutaneous aspect of arm

what is the average life for autogenous and prosthetic? | infection rate?

3, 2 years | 1-10%

What causes recirculation?

if dialysis flow exceeds AVF flow venous outflow stenosis arterial inflow stenosis needles too close

What causes pseudoaneurysms? How to treat?

multiples punctures at same sites | tx reserved if enlarging

What causes autogenous access aneurysm? what is tx?

usually a result of outflow stenosis can't continue cannulation must fix relocate more proximally

What are features of a seroma? how to manage?

``` not uncommon for prosthetic usually resolve without intervention usually near arterial anastomosis may be associated with low grade infections usually occur within first month new tunnel usually best management ```

When does stew occur? | what is the cause?

usually immediately but can happen up to a year | prox or distal stenosis

What is the grading system for steal?

0: no steal 1: mild-cool extremity, flow aug with access occlusion 2: moderate-intermittent schema only during dialysis, claudication 3: severe-ischemic pain at rest, tissue loss

What are RF for steal?

``` hx of steal elderly multiple prior access PVD DM ``` prosthetic brachial artery

What is treatment for steal?

``` DRIL procedure banding ligation RUDI (revasc using distal inflow) Proximalization of anastomosis ```

What is target DBI and pressure for banding ?

DBI 0.6 or pressure 50mmhg

What are three types of neuropathy patients with HD can get?

systemic disease neuropathy (ureic) mononeuropathy from compression (carpel tunnel) HD patients get it more frequently iscchemic monomelic neuropathy

What is IMN? What re the RF?

acute vascular compromise to the median, radial, ulnar nerves DM, from brachial, older, PReexisting neuropathy not seen distal to brachial

What are symptoms associated with IMN? tx?

pain, weakness, paralysis of muscles of forearm often with sensory loss within hours hand is warm, palpable pulses, no muscle ischemia surgical emergency with ligation or revasc

What is aetiology of IMN?

AC region is watershed for vasa vasorum of the three upper limb nerves

What are signs of outflow stenosis on dialysis?

High static venous pressure Low flow rates Urea clearance

What kind of balloons do you use for venous angioplasty?

High pressure Usually stm 24-28 Sustained inflation

What stents are best used for venous stenting?

Covered stent | Hyperplasia can come through bare metal

Where does the DRIL proximal anastomosis need to be?

Proximal to the anastomosis by 5-7cm because otherwise there is a pressure drop just distal to the proximal bypass anastomosis

Why does proximalization of the anastomosis work for steal?

It lengthens the anastomosis so the resistance of the avf. | Same for RUDI

What is the cutoff for DBI for ischemia?

0.3-0.4