fistula (arteriovenous fistula -avf)
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1
Subcutaneous anastomosis (communications)
of an artery to a vein, allowing blood flow
directly moves from artery to vein
Arteriovenous fistula (AVF)
2
3
AVF is a continuous circuit (not only anastomosis)
Starts at the heart and ends at the heart
The circuit:
Usually the anastomosis is made at the wrist
between the radial artery and the cephalic vein4
Advantages of AVFLower risk of infection
Lower tendency to clot fewer 2ry interventions
Lower hospitalization rates (lower complication
rates ,lower morbidity and mortality)
Allows for greater blood flow
Long-term patency (improved performance with
time)
Less cost of implantation and maintenance.5
Disadvantages of AVF1. Slow maturation and failure of maturation
2. More difficult to needle.
3. Increase in size with age and aneurysm
formation.
4. Cosmetic appearance of dilated veins.
6
Vascular anatomy of upper limb
• Basilic vein: drain medial side of upper limb
• Cephalic vein: drain lateral side of upper limb7
Types of common arteriovenous fistula according to method of anastomosis:
8
Types of common arteriovenous fistula according to its site in the upper limb
Forearm
AVF
Radial artery to cephalic vein
Radial artery to basilic vein
Radial artery to any other transposition
Arm AVF Brachial artery to cephalic vein
Brachial artery to basilic vein
Brachial artery to any other
transposition9
1.Radial–cephalic AV fistula ( wrist )
10
2.Brachial–cephalic AV fistula (elbow)
11
3.A transposed brachial basilic vein fistula
12
13
•Pre-operative care in hand for AVFThis begins as soon as finish vascular assessment
and site for access was decided.
Don’t insert peripheral IV catheters or cardiac
pacemaker
Don’t use for blood draws or IV drugs
Don’t use for taking blood pressure or try any
surgical procedures
Surgeon may ask for duplex ultrasound.14
Post-Operative care of AVF or AVGsImmediately following surgery (half-hourly at first),
the site of AVF should be checked for :
Excessive bleeding, haematoma, swelling, pain and
later signs of infection such as raised temperature.
Check radial pulse, colour, movement, warmth, and
sensitivity of affected limb to ensure blood flow
reaches extremities (peripheral circulation).15
Assess the access patency: palpate (thrill) or listen
(bruit)
Monitor BP and hydration status, to prevent access
clotting.
Elevate the access arm to help minimize oedema
and swelling.
Assess patient for pain
Report any abnormality to medical team ASAP.16
Patient Education (Daily Care)Good fistula care will help maintain the patency of
the vascular access.
Education is the responsibility of the nurse:
•Check the thrill at least once daily
•Avoid tight clothing , jewellery or watch
•Avoid carrying heavy object
•Avoid exposure to extremes of heat/cold 17
Avoid check BP, venipuncture or IV drugs ,
sleeping on the access arm
Use the access site only for dialysis
Wash the access with soap and water pre-dialysis
Signs of infection (pain, swelling, redness…….)
Absence of thrill must be reported to the renal unit.
(The fistula may need 6–8 weeks to mature and
ideally ≥12 weeks. )18
19
Cannulation is one of the 1ry causes of AVF failure
Sequences of needle punctures into the vessel wall
Endothelial injury leukocyte adhesion migration
of smooth muscle cells from the media to the intima
and proliferation.
Intimal hyperplasia thickening of the vessel wall
venous stenosis (main cause of access failure).
Infiltration, aneurysms and hematoma needle-
induced vessel injury 20
Personal protective devices
(Standard Precautions)Strict hand washing
Eye protection (face shield or goggles)
Mask
Gloves
(Use according to unit standards to ensure staff
protection) 21
Rapid examination AVF
• LOOK
• FEEL
• LITEN
22
Fistula maturation
Rule of 6's
6 weeks old
6 mm deep
6 mm fistula diameter
600mL per min flow 23
Skin PreparationPatients should wash their hands with anti-bacterial
soap and water before dialysis scission
Clean the skin using 2% Chlorhexidine gluconate
solution with alcohol (drying time 30 seconds),
Povidine-iodine (drying time 2–3 min), using friction
and a circular motion
Leave the solution to dry, prior to needle insertion
Do not touch skin after cleaning (If touch, re-clean)24
25
Local Anesthetic
Use of topical anaesthesia (lidocaine
cream) on site of cannulation at least
half an hour prior to cannulation.
26
Needle types
Two main types
1.Metal needle 2.Plastic needle
27
Metal needle28
Plastic needle 29
General rules for cannulation The initial cannulation will be a sharp metal needle
(metal needles are either sharp or blunt bevel).
To begin rope ladder/rotating site technique
Same-site cannulation in order to establish tunnel tracks
for the buttonhole technique.
Plastic cannulas can be left in the vessel for a period of
time to develop the buttonhole tunnel track.30
Sharp needles, used for the rope ladder
technique, have a sharp cutting edge.
Blunt needles, designed for the buttonhole
technique, are rounded on top (no sharp edge)
Black and red dots indicate the position of the
needle even during the treatment ( to know if
flipping happen after insertion of needle ).
Wing colour indicates needle diameter 31
Needle length1. Metal needles are range from 2.5cm to1.5cm
(which is for shallow new fistula).
2. Plastic cannula needles can be up to 3.8 cm (which
is for deep AVF)
32
Metal needle Plastic needle
• Cannulation is easy
• Miscannulations is low
• Low cost
• Severe vessel injury
• Higher risk of needle infiltration
during taping or mid-treatment
• Limited areas for Cannulation
• Less comfortable for patients’ arm
movements during the dialysis
• Not suitable for deep AVF cannulation
. Difficult
. High
. Higher
. Less
. Low
. Increased
. Comfortable
. Suitable 33
Needle site selection (Placement of needles)
4-5 cm (1.5-2 inches) apart, hub to hub, if
needles in the same direction
2.5 cm (1 inch) apart, hub to hub ,if needles
in opposite direction
Insertion site or needle tip once inserted, 4
cm (1.5 inches) away from the anastomosis
34
35
Venous needle pointing in the direction of the
blood flow
Arterial needle pointing toward the arterial
anastomosis.
Venous needle must point toward the venous
return and arterial needle, may point in any
direction.
May use ultrasound mapping for depth and size.36
37
38
Needle size selection 17 gauge needle for first attempts and for one
week with two needle cannulation without
complication
Increase needle gauge till 15 gauge needles
39
During choice the needle size , Must follow the
2:1 rule- arterial and venous pressure should not
exceed 50% of the pump speed e.g., 400 ml/min
blood pump speed, arterial and venous pressure
should be -200/200 mm/hg respectively
Arterial and venous pressure should not exceed -
250 or 250 mm/hg to avoid damage to the access
40
Back eyeThe arterial needle should always have a back-eye
It should be smooth and flat so that its rim does not
cut into the vessel during needle insertion or
withdrawal.
Maximize flow from the access.
Prevents suction of the needle to the inner vessel
wall and reduces the need for rotating the needle,
which adds trauma to the AVF.41
42
Bevel position/ flipping of needleAngle of insertion is 20-35 degree (depending on
vein depth)
The retrograde direction of the arterial needle and
bevel down cannulation increase possibility of
access failure
The antegrade direction of the arterial needle with
bevel up cannulation may improve access survival 43
Avoid flipping (rotating)the needle as this will
cause coring of the vessel
If flipping is essential as in case of increased
needle pressures, must be done carefully to avoid
damage to access (if fistula needles with a back-
eye the need to flipping the needle is decreased)44
Better use the ultrasound to determine optimal
cannulation sites and assess needle position,
before re-positioning the fistula needle
45
Number of attempts Better to use the portable ultrasound if available
for assessment of needle position and vein
depth/diameter
If cannulation is failed or infiltration occurs, call
cannulator or clinical educator
Don’t push saline or blood ,if unable to aspirate
blood from needle46
If doubt that needle has infiltrated, remove the
needle to decrease vessel damage and apply ice
If patient has received heparin, leave the needle in
place , apply ice and give protamine sulfate
Consider resting the access until infiltration and
bruising has improved. (Follow unit policies)
The additional attempt must be done by an expert
cannulator , if the dialysis is life saving and better
use single needle dialysis (when available) 47
Securing of needles Needles should be secured at the same angle of
insertion to avoid change in needle position and
minimize risk of infiltration
It also should be secured during treatment to avoid
accidental malposition or dislodgment of needles
Access limb and connections should be visible at
all times and should not be covered with blankets.
(Follow unit policies). 48
Needle Removal and HemostasisNeedles should be removed at the same angle of
insertion
Do not apply pressure while the needle is in the
vein
Once the needle is completely removed, use a 2-
digit technique (one finger at the skin level and one
at the vein level) for maximum hemostasis49
Dispose of the needle ( follow Occupational Health
standards)
Make press at least for 10 min without releasing
pressure (during applying pressure, ensure a thrill
can be felt in the access)
If thrill cannot be felt, remove hand slowly and
assess the thrill
50
Troubleshooting Needle Placement and
increased venous and/ or arterial pressures. Decrease blood pump speed
Measure blood pressure and review previous clinical
records to determine baseline blood pressure, venous
and arterial pressures and blood flow rate
Assess thrill and bruit and observe for infiltration
(swelling)51
Carefully reposition access limb
Use portable ultrasound to check position of
needle prior to re-positioning or adjusting needle
(if available)
Carefully adjust tape or place a small gauze under
the needle wings (as needed), while closely
monitoring venous and arterial pressures
If successful, secure needle in position with tape
while monitoring venous and arterial pressures. 52
If unsuccessful, recirculate patient’s blood and
recheck needle position with portable ultrasound If
repositioning is unsuccessful, remove fistula needle
Before re-cannulation, ask help the clinical educator
nurse
Repeat clinical assessment of AV access (thrill, bruit
and portable ultrasound) prior to repeating
cannulation.
Better to avoid repeated cannulation
(Follow unit policies).53
Complications of Cannulation of Needle
2.During HD
1.During cannulation 3.On needle removal
54
During cannulation (extravasation)Needling an AVF which is too small, not mature
enough, or very mobile can easily lead to
extravasation, the needle may be inadvertently pierces
through the side or back wall of the fistula.
Signs and symptoms of extravasation include:
1.Pain
2.Swelling
3.Bruising.
55
Extravasation is treated by applying pressure, ice, and
administering analgesia.
Blown arterial needle with satisfactory flow can be
used but extravasated venous needle should not be used
for HD and use alternative access till the swelling
subsides.
If extravasation is a usual problem, the patients should
only be needled by experienced nurses with use of
small-bore needles and referral for a surgical opinion.56
57
Problems during HDNeedle dislodgement
Can be identified by pressure alarms on the
machine, bleeding from needle entry site,
excessive pain, swelling and bruising
May be resolved by adjusting the needle or
by removing the needle and re-cannulation
58
Suckling up of needle against the
vessels wall
Reduced arterial pressure and mild
pain or vibration at the arterial needle
site
The needle will need to be rotated to
achieve a good flow.
59
Needles fall out during HD
Result from poorly secured needle sites
or excessive patient movement.
Pressure on needle hole, stop HD and the
extracorporeal re-circulated.
Once haemostasis is achieved the patient
may be re- cannulation and start HD.
60
Problems following dialysis ( on needle removal)
Delayed haemostasisMost common complication following HD
Not turning off the heparin infusion soon enough
Using too much heparin
Inadequate pressure being applied on site of cannulation
Pressure being taken off too soon following needle removal.
If over-heparinization is suspected protamine may be
administered.
61
Cannulation Techniques
Site-Rotation Buttonhole
Known as:1 .Rope ladder
2 .Rotating sites
Known as:1 .Constant-site
2 .Same-site
62
Rope ladder ( Site- Rotation technique):
Cannulation sites are rotated up and down the
AVF to use its entire length with equal
distribution of the puncture sites
This is the classic technique used in most
dialysis centers
Cannulation in straight line at least 1–2cm for
each cannulation site
63
No need to ‘straighten out’ by pulling on the
vessel to cannulates, the vessel will retract
into its original position when released and
lead to an infiltration
Each treatment requires 2 new sites
Disadvantage:
Small dilatations over the whole fistula.
Concerns of ‘ one-site-itis’
64
Advantage:
lower rate of infection
Help expand the lifespan of the fistula.
Changing cannulation site gives the previous
needle site time to heal and decrease the chance
of formation of aneurysms.
It is thought rope ladder needling reduces the
risk of stenosis.
65
66
67
68
“ONE-SITE–ITIS”
Occurs when cannulates the needle in the same
general area, session after session
Causes aneurysm and stenosis formation
69
Buttonhole TechniqueMethod in which an individual cannulates the AV
fistula in the exact same spot, at the same angle and
depth of penetration every time
After about 10 cannulations using sharp dialysis
needles, the buttonhole site will develop a scar tunnel
track.
This track is the same as a pierced ear that has scar
tissue formed and will cause less to no pain or bleeding
when cannulated.
70
After the buttonhole is created, a blunt dialysis needle
should be used, which eliminates the risks of cuts and
bleeding to the tract.
71
ADVANTAGES
May prolong AVF lifespan
Reduce needling attempts
Reduces pain
Reduces bleeding and hematoma
Reduces infiltration
Reduces aneurysms
Promotes self-care and self-dialysis
Use blunt needles, which require no safety device
72
DISADVANTAGES
Requires same cannulator, same angle, same
location
High rate of infection
Concerns of ‘one-site-its’
Difficult with fistula covered by:
1.Heavily scarred skin
2.Large amount of subcutaneous tissue
73
Indications of buttonhole technique:
Indication to use rope ladder technique
• AVF is short in length or has short usable segments
• AVF is relatively straight
• AVF with tortuous anatomy
• Patient has hand tremors.
• AVF with aneurysmal dilatation
• Poor vision or placement of needle on the BH lead to the creation of multiple tracts within the BH
74
Indications of buttonhole technique:
Indication to use rope ladder technique
• AVF is difficult to cannulates (self cannulation)
• Patient reports or demonstrates difficulty visualizing the BH site.
• AVF is mature • Multiple tracts within the BH
• Patient preference.• Needle phobia
75
Complications of fistula
76
1-Aneurysm , Pseudo aneurysmA consequence of an AV fistula creation is
thickening and enlargement of the vein walls due to
arterialization.
Over time, flow in the fistula increases and the
vein enlarges and may become tortuous.
An aneurysm is a weak spot in the wall of the
fistula which causes ballooning of the vessel wall.
77
This aneurysm is secondary to repetitive
cannulation in the same area (same=site itis)
which lead to weakness of vessels walls
Pseudo aneurysm collection of blood in the tissue
surrounding a vascular access can occur if
improper control of bleeding after the dialysis
needles is removed (pulsating extravascular
hematomas).
78
Aneurysm and pseudo aneurysm may also be
caused by a proximal stenosis.
Patients with aneurysms may present to the
emergency department reporting extremity pain,
neurologic dysfunction secondary to aneurysmal
impingement of surrounding nerves, significant
thinning of overlying fistula skin, or hemorrhage
secondary to this skin erosion
79
Diagnosis Both AV fistula aneurysm and pseudoaneurysms
can be identified with the use of Doppler US.
80
Management: Changing needle sites and vascular surgery
for operative repair.
Surgery is indicated when the aneurysmal
dilatation is >2cm, pulsatile pain is present in
the aneurysm, and the overlying skin appears
glossy and discoloured (risk of rupture,
perforation and ulceration)
81
2-Infection:AV fistulas have lowest risk of infection of any
vascular access type.
Pre- cannulation must checking signs of infection
over skin of AVF
1.Redness or raise temperature on exit site of fistula
2.Swelling or hardness.
3.Purulent discharge from needle sites.
4.Tenderness or pain.
82
Causes
Inadequate disinfection of the skin
Contamination of the needle
Manipulation of the needle during dialysis
Scratching of the puncture site
Poor personal hygiene
Contamination due to bathing.
83
84
Management:
Must be managed urgently as it can lead to
thrombosis or sepsis if left untreated.
Do not cannulates
Bloods cultures must be obtained and the access
site swabbed to confirm diagnosis.
Antibiotics mostly necessary.
Patient may need admission and temporary dialysis
access
85
Prevention:
1. Pre and post treatment washing of access
2. No scratch on the access site
3. Appropriate skin antisepsis
4. Sufficient antiseptic-skin contact time
5. Cannulation while antiseptic is dry
6. Maintain needle sterility
7. Do not cannulate through scabs or abraded
areas
86
3-Thrombosis (clotting)The most common complications of AVF.
Venous stenosis resulting in reduced blood flow,
infection, recirculation, damage to the vessel wall, and
eventually clotting of the fistula.
87
Causes
Surgical/technical problems
Preexisting anatomic lesions
Premature use
Poor blood flow or hypotension
Hypercoagulation
Fistula compression (Patient compressing
while sleeping)
88
Clinical
Absence of pulse/thrill on palpation ( feel firm)
Absence of bruit on auscultation
No blood or blood clots can be aspirated
89
Management ( Urgent treatment is required to
prevent the failure of the access)
Do not needle
Take blood sample to see if HD necessary
Inform the nephrology team immediately.
Interventional thrombolysis
Surgical thrombectomy
Prophylactic surveillance (warfarin)
May require new access
90
4-BleedingCauses
Bleeding after remove needle
Anticoagulation/not stopping prior to end of HD
Improper pressure with needle withdrawal
Bleeding during treatment (oozing around needle
or infiltration) = fragile vessel wall or back wall
penetration don’t flip the needles
91
Symptoms and signs
Needle sites bleed >10mins following HD
92
Management:
Stop anticoagulation 1hr prior to the end of HD
Apply directed pressure
Consider coagulants (Protamine sulfate)
Review needle-removal technique
Review clotting disorder
Review medications and BP
Educate patients about post-treatment hemostasis
and what to do at home ,if the needle site re-bleed
93
5-Infiltration = Hematoma
The pathological accumulations of substances in
tissue or cells which are normally are absent.
Causes: an improper needle flip or taping procedure
can cause an infiltration.
94
How to prevent the infiltration:
During cannulation
Don’t flip needle
Don’t lift needle in vein
Check for flashback and aspirate
Flush with NSS to ensure, that there are no signs
or symptoms of infiltration (Saline causes much
less damage and discomfort than blood if an
infiltration occurs)
95
Post hemodialysis
Apply gauze without pressure during
removal of needle
Remove needle at insertion angle
Apply pressure with 2 fingers
Hold pressure 10–12 minutes
96
Management of infiltration:
Elevate arm above heart
Ice 20 minutes on/20 minutes off for 24 hours
Warm compresses after 24 hours
Let fistula rest
Second infiltration: Notify vascular access team
97
Hematoma
If bruising or hematoma occurs after dialysis, the
surface skin site has sealed but the needle hole in
the vessel wall has not.
Use 2 fingers per site for hemostasis
It is crucial to apply pressure to both the skin and
access wall puncture sites
98
6-Poor arterial flow and increased venous
pressure
May be due to location or position of needle
May be there are thrombosis or stenosis or
significant recirculation.
This poor flow may lead to clotting of the AVF.
99
Management:
An angiogram or Doppler US should be performed to
detect stenosis or thrombosis.
Recirculation tests can also be used to determine the
significance of venous stenosis.
Recirculation >10–15% suggests access malfunction.
R = {(P – A) / (P – V)}x 100
P= BUN periphery, A= BUN arterial line,
V= BUN venous line and R =the percentage
recirculation
100
7-Stenosis:Most common complication
Hyperplasia in lumen (usually arterial side)
Frequent cause of fistula failure
Causes:
Surgery to create AVF
Turbulence-Pseudoaneurysm-aneurysms
Needle-stick injury
101
Type of stenosis:
1-Juxta-anastomotic (most common stenosis in AVF)
2-Mid-access stenosis
3-Outflow stenosis
4-Central vein stenosis
102
Clinical key that there is stenosis:
Clotting of the extracorporeal circuit 2 or more
times/month
Persistently swollen access extremity
Changes in bruit or thrill (ie, becomes pulse-like)
Difficult needle placement
Blood squirts out during cannulation
Elevated venous pressures
103
Inability to achieve optimum blood flow rate.
Changes in Kt/V and URR
Recirculation
Prolonged postdialysis bleeding
Presences of frequent episodes of access clotting
104
Diagnosis
Physical examination and/or flow measurement
should be performed as soon as possible.
Duplex scan/fistulagram.
MRA should be performed
Recirculation studies
R = ([P - A] / [P – V]) x 100
Where P= BUN periphery, A= BUN arterial line, V=
BUN venous line and R =the percentage
recirculation
105
Parameter Normal Stenosis
Thrill Only at the arterial anastamosis
At site of stenotic lesion
Pulse Soft, easily compressible
Water-hammer
Bruit Low pitch, ContinuousDiastolic & systolic
High pitch, DiscontinuousSystolic only
106
Management
Call surgical team for corrective treatment:
Percutaneous trans-luminal angioplasty is the first
treatment option for venous outflow stenosis.
Radiological intervention ( stent or balloon
dilatation)
Surgical revision.
Temporary access
107
Steal syndrome: Deprivation of blood distal to
AVF/AVG
Steal syndrome (ischemia of the hand)
Inadequate blood supply to the hand, caused by
the AVF “stealing” blood away from the
extremity, this causes hypoxia (lack of oxygen)
to the tissues of the hand resulting in severe pain
and neurologic damage to the hand can occur.
108
Risk factors
Brachial arterial origin
Diabetes mellitus
Peripheral vascular disease (PVD)
Female gender
109
Clinical picture: Most patients are asymptomatic
Cold sensation and pale colour of the fingers
Ischemic pain
Diminished or absent pulses
Capillary refill will decrease
Neurological and soft tissue damage to the hand can
occur, resulting in mobility limitations (eg, grip
strength, skill), loss of function, ulcerations, necrosis
110
111
Diagnosis of Steal Syndrome
Clinical investigation –Allen test.
Noninvasive imaging tests: measurement of
digital pressures and access flow
measurements.
Angiography
Pulses, BP, pulse oximetry, Doppler, duplex
US should be carried out.
112
Allen test.
A medical sign used in physical examination of
arterial blood flow to the hands.
The hand is normally supplied by blood from both
the ulnar artery on the little finger-side and the
radial artery on the thumb-side.
113
These two arteries connect to form an anastomosis,
so if one of the arteries becomes compressed or
occluded, the blood supply from other artery will
maintain the blood supply of hand
Compressing both the radial and ulnar arteries
simultaneously (30 second ) while patient open and
close his hand, allowing the blood to drain via the
venous system, causing the hand to blanch.
114
While the patient opens and closes his hand, release
one of the arteries, evaluating how fast refill occurs
to the hand.
Repeat the procedure again, this time releasing the
other artery while timing the refill.
Refilling of less than 3 seconds is considered a
negative test and indicates there is adequate blood
flow in the palmer
115
116
Management of Steal Syndrome
Early referral to the surgical for revision of access
the DRIL distal revascularization-interval ligation,
can successfully treat steal and ischemia
Pain control.
Encourage patient to wear a glove on affected
extremity.
Steal symptoms may improve due to the
development of collateral circulation.
117
Examination of the mature hemodialysis arteriovenous fistula
118
Routine physical examination of the fistula lead to
early detection and treatment of any problems
The 2006 National Kidney Foundation Kidney
Disease Outcomes Quality Initiative
(NKF-K/DOQI) guidelines and the 2008 Society
for Vascular Surgery practice guidelines
recommend that physical examination must be
performed on all mature arteriovenous fistulas
(AVFs)
119
Examination must be done every hemodialysis
treatment.
Must be known by all clinical staff who dealing
with fistula
It is easy
Inexpensive
To detect common problems associated with
hemodialysis access
120
Inspection
Position of the fistula
1. Radiocephallic
2. Brachiocephallic
3. Transposed cephallic
Presence of other vascular access
1. Central venous access
2. Peritoneal access
3. Graft
121
Expose the entire extremity with the AV access
Compare any change in the limb to the non-access
limb
Signs of infection (warmth, erythema, discharge ...)
Presence of bruising (hematoma) , swelling
(edema), and collateral veins (visualize entire arm
and upper chest)
Aneurysm and pseudoaneurysm
122
Outflow stenosis (Arm Elevation Test): When the
access arm is elevated to a level above the heart.
o The absence of a stenosis, the vein where the blood
flows out
(Should collapse , Become less prominent)
o If a stenosis is present, the portion of the fistula
distal to point of stenosis remains distended, while
the proximal portion collapses
123
124
Access-induced ischemia or steal syndrome (signs
of cyanosis of the finger tips and delayed capillary
refill of the nail beds, hand pallor and decreased
range of motion)
Location of anastomosis and evidence of healing
incision lines
Skin integrity (rash, blisters, scabs or eroded
cannulation sites)
125
Appropriateness of vessel size (depth and diameter)
for cannulation suitability
Location for previous cannulation sites (avoid thin,
white, shiny aneurysmic areas).
Central venous stenosis: (If generalized swelling of
the arm and/or collateral veins on the upper limb is
identified, the possibility of central venous stenosis
needs to be ruled out)
126
Palpation for AV fistula
Evaluate for possible cannulation sites =
superficial, straight vein section with adequate and
consistent vein diameter
Feeling of fistula
Use a two- or three-finger approach to roll fingers
across the AV fistula to determine width and depth
of access
Check for tenderness
127
Pulse
o Normal AVF is soft, compressible and non-
pulsatile
o A pulsatile fistula is suggestive of obstruction or
stenosis (venous side).
o The strength of the pulse is related to the severity
of this obstruction
128
129
Temperature Change
Feel the access skin temperature
o Warmth = possible infection
o Cold = decreased blood supply
Assess and compare temperatures in both the
access and non-access limb.
130
The thrill must be assessed by palpating the entire
length of the AV fistula to determine access patency
(The vein should be soft and easy to compress)
Normally a thrill has a systolic and a diastolic
component
A thrill is a buzzing or vibration felt (soft continuous
thrill)the blood flow created by the high pressure
arterial system merging with the low pressure venous
system}
131
A strong thrill should be palpable at the arterial
anastomosis diminishing distally, closer to the venous
end.
Change can be felt at the site of a stenosis; becomes
‘pulse-like’ at the site of a stenosis
A weak thrill may suggest a stenosis at or near the
anastamosis (arterial side)
132
Occasionally, a thrill can be palpated in the axillary
or subclavian region, particularly in thin chested
individuals and may suggest presence of central
venous stenosis.
133
Pulse augmentation test ( for inflow stenosis) The normal AV access is soft and compressible but
non-pulsatile.
If the access occluded several centimeters above the
anastomosis, there should be augmentation of the pulse
in the distal portion.
The degree of this “pulse augmentation” is
proportional to arterial inflow pressure, making this
maneuver, an excellent tool to diagnose inflow
problems.
134
If the pulse augmentation is poor ( weak or absent
pulse with obstruction ) poor arterial inflow
135
Auscultation Listen for Bruit
Begin at the AV anastomosis and continue along the
length of the access noting any changes in pitch and
amplitude of the bruit.
Bruit: A well-functioning fistula should have
continuous, machinery-like bruit on auscultation (low-
pitched whooshing of blood through the fistula heard
through a stethoscope) created by the turbulence at the
anastamosis.
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An obstructed (stenotic) fistula may have a
discontinuous and pulse-like bruit rather than a
continuous one and also may be louder and high-
pitched or ‘whistling’ Louder at stenosis than at
anastomosis
Absent bruit usually indicates that the access has
clotted or thrombosed.
NO bruit – NO cannulation
Portable ultrasound to make good report about AVF.
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