Arterio Venous A ' V' ACCESS

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Arterio Venous (A . V.) ACCESS

• Case Presentation

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A . V. ACCESS

• A 26 year old male weights 36 kg with height 155
  cm ,has CRF from age 15 due to stones and began
  H.D. from 18.
• He is a very malnurished and uncooperative
  patient,is a smoker and addict .He underwent
  several operations for AV fistula.and had many
  traumas to his AVF.
• From 1373 79 (7 yrs) AVF
• Temporary catheter 4 months
• AVF 4 months
• AV graft 2 months
• Perm cath 11 months
• 2nd permcath 5 months
• In the last few months ago he had chills and
  fever specially on HD ,eventually Rt. Side
  bacterial endocarditis was detected, and the
  permcath should be removed.

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A . V. ACCESS

• Receiving of AVF depends on
• 1- Time of referral for H.D. and Vas. Access.
• 2- Type of fistula placed.
• 3- Patient demographic.
• 4- Preference of nephrologist.
• 5- // // surgeon.
• 6- // // dialysis nurse.
• 7- Vascular anatomy of the
  patient.

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A . V. ACCESS

• Usable of fistula for dialysis
• Adequacy of vessels
• Surgeons experience
• Patient demographics
• Nursing skills
• Minimal acceptance dialysis blood flow
• Attempts to revise immature fistulas

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A . V. ACCESS

• Optimal outcme depends on
• A mltidisciplinary team approach to V.Access.
• Consensus about the goals among all interested
  parties.
• Early referral for placement of V Access.
• Restriction of V Access procedures to surgeon
  with interest and experience.
• Routin preoperative mapping of the arteries and
  veins.
• Close ,ongoing communication among the involved
  parties.
• Prospective tracking of outcome with continuous
  quality assessment.

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A . V. ACCESS

• A.V. Access procedures and complications accounts
  for 20 of hospitalizations of dialysis
  patients in the U.S.A. and it costs 1 billion
  annually.
• In U.S.A. at 1990 s 20 dialyzed with fistula.
• Now 40 are dialyzing with
  fistula.
• I n Al Zahra 86 // // .

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A . V. ACCESS

• Factors affects prevalence of A V fistula
• 1- geographic variation in USA 224
• 
  in Europe 80
• 
  in Al-Zahra 86
• 2- femalelt male
• 3- age
• 4-diabetes
• 5-peripheral vascular disease
• 6-obesity
• 7-lower socioeconomic states

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A . V. ACCESS

• Factors affects fistula placement
• Timing of fistula placement
• Type of fistula
• Patients demographic

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A . V. ACCESS

• Factors affects fistula placement
• Timing of fistula placement
• The mean maturation time of a new AV
  fistula is about 2-4 months .
• Placement of a fistula , if the patients is
  on dialysis ,leads to prolonged hemodialysis with
  a temporary catheter, with complications
  including poor blood flow, frequent thrombosis
  or malfunction and life-threatening bacteremia.

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A . V. ACCESS

• At initiation of dialysis
• 66 of US patients use a catheter,
• 22 use a graft ,and only12 use a fistula
• In Al Zahra ,50 use AV Fistula and 50 use a
  catheter

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A . V. ACCESS

• Type of fistula (in order of preference)
• Radio-cephalic AVF
• Brachio-cephalic AVF
• Brachio-basilic Transposition AVF or
  Arteriovenous Graft (PTFE)
• Cuffed Tunneled Central Vein Catheter

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A . V. ACCESS

• 3- Patient Demographic
• Lower likelihood of fistula placement and
  initially more likely in the upper arm
• Women
• Diabetes

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A . V. ACCESS

• Patient evaluation prior to access placement
• History physical examination
• Diagnostic evaluation
• Venography ,indications
• Edema in the extremity
• Collateral vein development
• Differential extremity size
• Current or previous subclavian catheter
• transvenous
  pacemaker
• Previous arm , neck or chest trauma or suegury
  in vein
• Multiple previous access
  

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A . V. ACCESS

• Patient evaluation prior to access placement
• 2-Diagnostic evaluation
• a) Venography
• b) Doppler Ultrasound
• c) M R I
• d) Arteriography

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A . V. ACCESS

• Wrist Fistula
• Advantages
• Simple to create
• Preserve more proximal vesseles
• Has few complications(vascular steal,thrombosis,in
  fection)
• Disadvantages
• lower blood flow rate

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A . V. ACCESS

• Elbow fistula (brachial-cephalic)
• Advantages
• Higher blood flow.
• Cephalic vein is easy to cannulate and
  cosmetic benefit.
• Disadvantages
• More difficult to create.
• More arm swelling .
• Increased incidence of steal.

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A . V. ACCESS

• Brachial-basilic (transposed) fistula
• Disadvantages
• Transposition produces significant arm edema and
  pain
• Higher incidence of steal

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A . V. ACCESS

• A V synthetic Graft
• Type straight, looped or curved
• Advantages
• Larger surface area for cannulation
• Easy to cannulate
• Short lag time from insertion to maturation
  (gt14days)
• Multiple insertion sites
• Variety of shape and configuration
• Easy for surgeon to handle,implant and construct
  the vascular anastomosis
• Easy to repair surgically
• Disadvantages
• 1. A V graft is expected to last 3-5 years

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A . V. ACCESS

• Tunneled Cuffed Catheter
• Temporary access of longer than 3 weeks
• Exhausted all other options
• Preferred site R I J V,R EJV, LIJV, LEJV, SC,
  Fe, Translumbar to IVC.
• Should not placed on the same side of
  maturation of AV access.
• Guided by U.S. and fluoroscopy.

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A . V. ACCESS

• Tunneled Cuffed Catheter Advantages
• Immediate HD (maturation time not required
• Universally applicable
• Ability to insert into multiple sites
• Venipuncture not required
• No hemodynamic consequences
• Ease and cost of catheter placement
  replacemant
• Ability to use over a few months
• Ease of correcting thrombotic complication

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A . V. ACCESS

• Tunneled Cuffed Catheter disadvantages
• High morbidity due to thrombosis ,infection.
• Risk of permanent Central venous stenosis or
  occlusion
• Discomfort and cosmetic dis of external
  appearance
• Shorter life
• Lower B. L. F. R ,requires longer H D time

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A . V. ACCESS

• Acute Hemodialysis V A noncuffed Catheter
• Less than 3 weeks duration
• For immediate use
• At the bedside in the femoral,Int.Jug,or S C.
• CXR after SC and Int Jug. Insertion prior to Cath
  use to confirm1) Cath tip at the Caval atrial
  junction or the SVC. 2) Exclusion complication
  prior to starting HD.
• Where available US should be used.

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A . V. ACCESS

• Acute Hemodialysis V A noncuffed Catheter
• Femoral Cath should be at least 19 cm length to
  minimize recirculation. Should not be in place
  longer than 5 days .
• Can be exchanged over a guide wire or treated
  with urokinase (if not infected)
• Infection (exite site ,tunnel, systemic ) should
  prompt the removal of noncuffed catheter.

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A . V. ACCESS

• Preservation of Vein for Access
• Arm veins should be preserved regardless of
  dominance. Cephal. V of nondominant arm should
  not be used in ch. Kidney dise., dorsum of the
  hand should be used.
• Instruct all pts. with Cr gt3 mg/dl and protect
  arm from venipuncture,IV catheter.a bracelet
  should be worn.
• S.C.vein, should be avoided for temporary access
  in all patients with kidney failure.

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A . V. ACCESS

• Timing of Access Placement
• Creatinine clearance lt 25 ml/min or ser.Crgt4
  mg/dl or whithin 1 year need for dialysis (refere
  to nephrologist before need for access.
• Primary AVF allow to mature(1 month or ideally
  3-4 months).
• A.V. graft placed at least 3-6 weeks.
• H. D. catheter should not be inserted until H.D.
  is needed.

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A . V. ACCESS

• Factors Affect Fistula Maturation
• Adequacy of vessels
• Patient demographics
• Women
• Old age
• Diabetes

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A . V. ACCESS

• Factors Affect Fistula Maturation
• Adequacy of vessels
• type of fistula
• Hand maneuver
• Antiplatelet agents before and up to 3-6 weeks
  after surgery .
• Experience of surgeon ( unexperienced surgeon
  lt12 access procedures surgery trainee performed
  or assisted in the procedure.

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A . V. ACCESS

• Factors Affect Fistula Maturation
• Adequacy of vessels
• Changes for successful maturation
• Dilation
• Blood flow rate( to avoid vein collapse and
  recirculation, the access B. F. should exceed
  the HD B. F. at least 100 ml/min.
• Mean HD B.F. in USA 400 ml/min
• 
  Europe 300
• Japan
  200

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A . V. ACCESS

• Factors Affect Fistula Maturation
• Adequacy of vessels
• The wall of the draining vein must hypertrophy
  to seal after withdrawal of dialysis needle.
• The fistula must be superficial enough for the
  landmarks to be appreciated and permit safe
  cannulation without infiltration.

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A . V. ACCESS

• Pre operative vascular information
• Venography
• Digital subtraction venography
• Sonography (method of choice )

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A . V. ACCESS

• Preoperative Vascular Mapping
• Minimum diameter criteria 2mm for the artery
• 2.5
  mm for the vein
• diameter lt 1.5 mm always failed .
• Lack of thrombosis or stenosis in draining
  central veins .
• Minimum diameter for graft placement
• vein 4 mm artery
  2 mm

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A . V. ACCESS

• Assessment of Fistula Maturation
• Expertise of dialysis nurse experienced nurse
  predicts 80 of the time , it is extremely when
  a potentially functioning fistula is compromised
  by laceration,infiltration and serious hematoma
  at the time of initial use .Formal certification
  of nurses for initial use.
• Minimum vein diameter by sono gt0.4 cm or blood
  flow of fistula gt500 ml/min .
• one criteria 70 maturation , both
  90 maturation , neither 33
  maturation,female 30 lower maturation

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A . V. ACCESS

• Successful fistula
• Presence of thrill or bruit or ,
• Ability to use the fistula for at least one
  dialysis session or ,
• Ability to use the fistula for H.D. for at least
  one month with a dialysis blood flow gt 350
  ml/min.

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