John C. Lantis II, MD
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To what extent does proactive vascular
access monitoring affect the incidence of AV
access thrombosis and abandonment
compared with clinical monitoring
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Hemodynamically significant outflow
stenosis leading to thrombosis is the most
common cause of prosthetic access
abandonment
Early studies suggested idntification and
correction of these stenosis could prevent
thrombosis and prolong graft longevity
RCTs have had variable results
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The National Kidney Foundation
The Canadian Society of Nephrology
Caring for Australians with Renal Impairment
 Recommend frequent, regular surveillance with
physical exam an some form of serial access flow
measurements
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Nine studies (1363 patients)
Surveillance vs. clinical monitoring
Surveillance followed by intervention led to a
non-significant reduction in risk of
thrombosis (.82)
…..and a non-significant reduction in
abandonment (.80)
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Three studies (207 patients) compared the
effect of vascular intervention vs. observation
in patients with abnormal surveillance results
Intervention led to a significant reduction in the risk
of access thrombosis (0.53)
…and abandonment (0.76)
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2006 Robbin
 Chronic HD – mean follow up 670 days
 Prosthetic only
 Surveillance
▪ 65 pts
▪ US every 120 days
▪ Thrombosis 18, abandonment 27
 Control
▪ 61 pts
▪ Physical exam/HD parameters TIW
▪ Thrombosis 27, abandonment 26
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2006 Polkinghorne
 Chronic HD – mean follow up 558 days
 Autogenous only
 Surveillance
▪ 68 pts
▪ Blood flow every 30 days
▪ Thrombosis 6
 Control
▪ 67 pts
▪ Physical exam/dynamic venous pressure TIW
▪ Thrombosis 4
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2005 Malik
 Chronic HD – mean follow up 670 days
 Prosthetic 216, Autogenous 147
 Surveillance
▪ 291 pts
▪ Urea recirculation, dynamic and static venous pressure,
ultrasound – weekly
▪ Abandonment 7
 Control
▪ 72 pts
▪ No access monitoring
▪ Abandonment 28
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The value of surveillance strongly depends on
the adequacy of clinical monitoring
Clinical monitoring by skilled personnel has a
positive predictive value of 70 to 90% in
prosthetic grafts, a 38% sensitivity and 90%
specificity
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Monitoring – is physical exam per DOQI
guidelines
 Absent thrill, pulsatile graft, abnormal auscultation,
persistent edema, venous collaterals on the chest wall
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Surveillance – refer to tests
 Serial access flow measurements
 Serial measurement of static dialysis venous pressure
 Prepump arterial pressure
 Duplex ultrasound screening
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flow rates as measured at end of dialysis
 < 600 ml/min
 Or a decrease of 25%
 Most useful for autogenous fistula
 Reverse the arterial and venous lines measuring
the rate of change in ultrasound transmission in
the venous line after saline
 DOQI recommends: Monthly measurement
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Primarily for grafts
(Dynamic VDP) – measured at low HD flow of
200 ml/min is a relative poor marker, too many
variables
Static VDP – at no dialysis flow
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Ratio to SBP
>0.4 suggestive of stenosis
>mean pressure ratio is 0.5
Should use as a trending tool, not a single
measurement
Indicitive of the ease with which blood is drawn
from the access at any particular setting
New autogenous access, if they have a problem
it is at the arterial inflow
Therefore, have an excessively negative
arterial dialysis pressure
Useful in new dialysis fistulae
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PSV at the graft venous anastomosis
PSV > 2.0 to immediate upstream velocities is
predictive
Positive predictive value of 80%
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Note although thrombosis rates are lower,
actual access survival is no different in the
two groups
However, lower incidence of thrombosis may
translate into a reduction in access related
costs and hospitalizations
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RR of access thrombosis
 Surveillance 90/406
 No surveillance 92/387
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RR of access abandonment
 Surveillance 94/614
 No surveillance 88/347
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Very low quality evidence
Suggests that serial surveillance of
asymptomatic AV access, accompanied by
intervention if an abnormality is found, tends
to decrease thrombosis and abandonment vs.
no surveillance
This difference is not statistically significant
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Regular clinical monitoring (inspection,
palpation, auscultation and monitoring for
prolonged bleeding after needle withdrawal) to
detect access dysfunction –very low quality
evidence
Suggest access flow monitoring or static dialysis
venous pressures for routine surveillance – very
low quality evidence
Suggest performing a Duplex ultrasound study
or contrast imaging in accesses that display
clinical signs of dysfunction or abnormal routine
surveillance – very low quality evidence