Hemodialysis Access

1
Hemodialysis Access

• Ultrasound Evaluation Before After Creation

2
Ultrasound - Advantage

• Noninvasive
• No contrast or risk of phlebitis
• Shows more vascular detail than physical exam
• May change the surgical management (AVF vs.
  graft)
• Increases visualization of veins suitable for
  native AVF placement
• Increases likelihood of selecting most functional
  vessel
• Determine possible cause for failure of AVF to
  mature
• Assess for stenosis
• Determine cause of perigraft palpable masses
• Hematoma
• Pseudoaneurysm
• Assist in determining most appropriate treatment,
  angioplasty or surgical

3
Basic Concepts

• Hemodialysis is for patients with end-stage renal
  disease
• 8,000 new dialysis patients per year
• Blood is cleansed by diffusion across a
  semipermeable membrane
• Dialysis is accomplished by AVF creation
  (preferred method), graft or central venous
  catheter placement
• AVF or graft
• Two 15 gauge needles are placed
• One distal, which takes blood from the patient to
  the dialyzer
• One proximal, which returns blood from the
  dialyzer to the patient

4
AVF Anastomoses Most Common
5
Graft Artery/Vein Anastomoses Most Common
6
Basic Considerations - continued

• AVF creation or graft placement
• Preferable placement is in the nondominant arm
• First access is generally in the forearm
• Saving the upper arm for future access
• Forearm graft is preferable for patients without
  suitable anatomy for AVF creation
• Thigh graft is generally a last choice
• AVF creation in the dominant arm may be
  preferable to placement of a graft in the
  nondominant arm
• Central venous catheter
• Higher infection rate
• Lower flow rates

7
Preferred Order of Access Placement
8
Forearm AVF

• Brescia-Cimino Fistula
• Radiocephalic fistula

9
Brachiocephalic Fistula
10
Brachiobasilic Fistula

• Vein transposition fistula

11
Forearm Loop Graft

• Brachial artery to cephalic vein

12
Upper Arm Straight Graft

• Brachial artery to axillary vein

13
Axillary-Axillary Loop Graft
14
Thigh Graft

• Common femoral artery to greater saphenous vein

15
Preoperative Vascular Mapping

• Preoperative evaluation may include
• Physiologic upper extremity arterial evaluation
• Ultrasound imaging
• Ultrasound imaging
• Linear ultrasound transducer
• gt 7 MHz
• Identify vessels
• Transverse imaging plane
• Evaluate vessel diameter and wall thickness
• Assess venous compressibility
• Depth from skin surface to anterior vessel wall
• Longitudinal imaging plane
• Color flow and spectral Doppler waveforms
• Assess arteries for intimal thickening,
  calcification and stenosis

16
Forearm Assessment

• Assess nondominant arm first
• Assess the radial artery in lower third of
  forearm
• At least 2 mm internal diameter
• Assess the ulnar artery if the radial artery is
  not suitable
• If no suitable artery is found in the nondominant
  forearm, assess the arteries in the dominant
  forearm
• If suitable artery is found in the nondominant
  forearm
• Assess the forearm veins
• Place a tourniquet below at or just below mid
  forearm
• The cephalic vein is the preferable vein for
  creation of a forearm fistula
• Adequate sized veins will be at least 2.5 mm in
  its internal diameter
• Assess for vessel continuity, branch points,
  compressibility
• Sequentially move the tourniquet to assess over
  its length and its insertion into the deep veins
• Assess the dominant arm is indicated

17
Minimum Diameter Criteria for AVF Graft Creation
18
Scanning Position
19
Radial Artery - Normal
20
Cephalic Vein - Wrist

• Diameter 2.9 mm Depth 3.4 mm

21
Upper Arm Assessment

• Assess the following vessels
• Brachial artery diameter at the antecubital fossa
• Cephalic vein from the antecubital fossa to its
  termination
• Need 2 cm of vein below AC fossa to create AVF
  anastomosis
• Median cubital vein
• Basilic vein if indicated
• Need 2 cm of vein below elbow for AVF creation
• If does not extend below elbow may still be used
  for graft
• Needs to have internal diameter or 4.0 mm
• Axillary vein and artery if indicated
• For possible creation of upper arm loop graft
• Subclavian, internal jugular and central vein
  assessment
• Luminal filling defects
• Doppler flow characteristics

22
Cephalic Vein - Abnormal

• Upper arm cephalic vein measuring with internal
  diameter of 1.4 mm

23
Upper Arm Assessment
Brachial artery - normal
Basilic vein - normal
24
Subclavian Vein Normal / Abnormal
Venogram Occluded brachiocephalic vein
25
Key Points - Preoperative

• If upper arm cephalic vein is unsuitable, a
  forearm AVF may still be possible depending on
  its eventual point of drainage, i.e. with the
  brachial, basilic or median cubital vein
• 2. Carefully assess branch points for focal
  stenosis
• 3. Cephalic vein diameter may be adequate but too
  deeply situated, i.e. gt0.5 cm, to be palpated
• 4. High origin of the radial artery may make it
  unsuitable for use as there is increased
  likelihood of a steal syndrome
• 5. It is important to assess brachial and radial
  arteries with Doppler spectral analysis to
  identify proximal or distal obstruction

26
Cephalic Vein
Adequate size, but too deep
27
AVF Maturity Assessment

• General Principles
• Large, dilated, easily palpated vein
• Sonographic evaluation
• Evaluate
• Feeding artery
• Above (cephalad) from the fistula
• Immediately below (caudal) to the fistula
• Fistula itself (arteriovenous anastomosis)
• Draining vein
• Diameter
• Depth
• Entire length

28
Sonographic Evaluation

• Evaluate utilizing
• B-mode, color Doppler flow spectral Doppler
• Spectral Doppler criteria
• Volume/Flow
• Should be at least 350 cc/minute
• In general a volume/flow of lt250 cc/minute
  suggest a failing graft
• Feeding artery 2cm above fistula
• Arteriovenous anastomosis
• Calculate systolic velocity ratio
• gt2.0 50
• gt3.0 time to do something
• Mid graft flow velocity of lt100 cm/s is
  considered abnormal
• Draining vein
• Assess over its length
• PSVs proximal to, point of distal to any
  narrowing
• Systolic velocity ratios

29
AVF Occlusion

• Absence of flow in the arteriovenous anastomosis
• Triphasic flow in the artery above the
  anastomotic site
• Phasic flow with respiration in the veins

30
AVF Anastomotic Stenosis
Feeding artery 2 cm upstream from AVF with normal
low resistance Doppler waveform but abnormally
low flow velocity
AVF anastomosis with elevated velocity and
systolic velocity ratio of 31 consistent with
stenosis
31
AVF Evaluation Key Points

• Assess for presence of large vein branches
• May divert flow from the primary draining vein
• Frequently inhibits maturing of draining vein
• May need to be ligated
• Assess subclavian, internal jugular and brachial
  veins as indicated
• Evaluate the feeding artery distal to the fistula
  for possible steal syndrome

32
Large Draining Vein Branch
Draining Vein
33
Central Venous Thrombosis
Internal Jugular - Thrombosed
MRV with left brachiocephalic vein and central
internal jugular vein and central subclavian vein
thrombosis
Subclavian vein Laterally
34
Graft Evaluation General Principles

• Greater incidence of
• Stenosis
• Infection
• Pseudoaneurysm
• Graft stenosis occurs due to intimal hyperplasia
• Most commonly at the venous anastomosis
• Surveillance methods vary institution to
  institution
• Ultrasound utilized for
• Evaluation of palpable focal mass
• Differentiate hematoma from pseudoaneurysm
• Intermediate likelihood of graft stenosis
• Arterial steal

35
Access Graft Sonographic Evaluation

• High resolution, gt 7 MHz transducer
• Evaluate with B-mode, color Doppler flow
  spectral Doppler
• Evaluate with Doppler spectral analysis
• Afferent artery
• 2 cm cephalad to arterial anastomosis
• Arterial anastomosis
• Graft body
• Arterial anastomosis
• Mid graft
• Venous anastomosis
• Any other point of interest
• Venous anastomosis
• 2 cm caudal to venous anastomosis
• Efferent vein

36
Access Graft Sonographic Evaluation

• Doppler criteria
• Systolic velocities
• PSVs generally range from 100 400 cm/s
• EDVs generally range from 60 200 cm/s
• Volume/Flow
• Will generally be gt300 ml/minute
• lt250 ml/minute suggests a reduction in graft flow
  to a critical level
• Increased spectral broadening
• Flow turbulence
• Systolic velocity ratio
• gt2.0 gt50 diameter reduction
• gt3.0 gt75 diameter reduction
• Some authors suggest a ratio of gt4.0 gt75
  diameter reduction
• Must also see visual confirmation of stenosis
  with the presence of poststenotic turbulence and
  low flow distal

37
General Classification Scheme

• Normal
• Arterial anastomosis velocity gt300 cm/s
• Mid graft velocity gt150 cm/s
• No visible narrowing
• Distended outflow veins
• Moderate stenosis
• Arterial anastomosis velocity gt400 cm/s
• Mid graft velocity 100-150 cm/s
• Decrease in lumen diameter
• Echogenic material within the graft lumen
• Wall abnormalities
• Severe stenosis
• Mid graft velocity lt100 cm/s
• Intraluminal echoes
• lt2 mm lumen
• gt50 diameter reduction by color image
• gt100 increase in PSV

38
General Classification Scheme

• Inflow stenosis
• Inflow anastomotic site gt400 cm/s with turbulence
• Monophasic spectra with graft compression
• Mid graft velocity lt100 cm/s
• No increase in velocity at venous anastomosis
• Outflow stenosis
• Arterial anastomosis velocity lt300 cm/s with
  decrease in velocity throughout graft
• Mid graft velocity of lt100 cm/s
• Focal increase in velocity gt300 cm/s
• lt2 mm lumen at stenosis
• Occlusion
• No Doppler signal
• Intraluminal echoes
• Graft wall appear to be collapsed
• Occluded vein may not be visible

39
Graft Stenosis
Stenosis at venous anastomosis
Doppler flow 2 cm upstream from venous anastomosis
40
Graft Stenosis
Angiography with gt50 narrowing
Spectral Doppler at venous anastomosis