Chap 73-77 Vascular Access Flashcards
What is the 1-year mortality for patients on HD?
22%
mean life expectancy 5.8y
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
Why wait >4-6 months before initiation of HD?
lower risk of death and sepsis compared to <1 month
Does plavix help keep AVF open?
there is no evidence to support that
What are catheter options for dialysis?
short term
double lumen, non-tunneled, noncuffed, <6 months)
What bacteria are associated with catheter infection?
S.Aureus, CONS, enterococcus, pseudomonas
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
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
Why is cephalic better then basilica vein?
easier to access for HD puncture
minimal dissection
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)
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
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)
What is femoral vein and SVG latency in UE AVF?
SVG not known, tends not to dilate
femoral vein 94% at 2 years
What is preferred vein and artery for LE AVF?
What size should anastomosis be?
GSV, femoral artery
4-6mm
Why are LE AVF bad?
high infection rates, higher likelihood of steal, higher rates of PVD
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
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
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
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
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
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
