ch 30 hemodialysis

reason for dialysis

chronic kidney disease and end stage renal disease

Goal of arteriovenous access is to

provide long term hemodialysis access

goal placement of fistula

as distally as possible in nondominant arm

having graft in distal nondominant arm this does what two things

• Preserves proximal vessels for potential future access

• Allows patient to carry out normal daily activities

why are upper extreities are preferred

lower infection rate and easier access

when is reintervention required

failure of AV fistula to mature and thrombose

what has a long term patency

autogenous fistulas

autogenous fistuals have blank and blank rate

lower maturation and higher early thrombosis

contradictions to procedure

• Central venous catheters

• Pacemakers

• Defibrillators

• Prior mastectomy

what is done to demonstrate intact palmar arch

allen teest

contradictions of preoperative eval

-intravenous line

-limited patient positioning

-open wounds

-dressing

which system should be evaluaated first

arterial

useable arterial measurement

greater than 2mm

why can’t calcified arteries be used

they will not be able to expand to allow for higher flow volume

what should be recoreded along entire length

diameter of veins

vein walls should be free from

thrombus, webbing, and calcium

when is fistual considered mature

dilated, easily palpable, flow rate of greater than 350 ml/min

suitable vein diamter

greater than 2.5mm

most common av access

cephalic to distal radial

Cephalic vein connected to distal radial artery at wrist

Brescia-Cimino fistula

other fistula aces

brachial to cephalic, basilic to artery

fistula maturity should take blank to blank weeks

8-12 weeks

indications for follow up

• Pseudoaneurysm

formation

• Mid-graft stenosis

• Hematoma formation

• Arterial stenosis

• Perifistula mass

• Decreased thrill

• Pulsatile flow

• Difficult cannulation

• Elevated recirculation time

(>12%)

• Elevated venous pressure

during dialysis (>200 mm

Hg)

• Low urea reduction rate

(<60%)

• Excessive bleeding

following dialysis

• Arm edema, infection

• Arterial steal syndrome

Risk factors that may preclude

maturation

• Central venous thrombosis, central

venous catheters

• Pacemakers or defibrillators

Physical exam

-assess for presence and quality of thrill

-edema and redness

-presence of collateral veins

-rotation of access sites

-focal dilations

doppler settings should be adjusted to blank setting

high-flow

B-mode abnormalities

• Perigraft masses

• Pseudoaneurysms

• Stenotic valves

• Intimal flaps

how to check for arterial steal syndrome

• Check for retrograde flow in distal native artery.

• Compress graft and reassess flow direction.

pitfalls of graft

-partial compression due to superficial location

-become anuerysmal, develop pseudo, become tortuous

Normal fistula characteristics

-no valves visible

-PSV 150-300

-EDV 60-200

-inflow should be low resistance and 30-100

-flow volume greater than 800 ml/min

Abnormal findings

-focal velocity increase 100% from adjacent segment

-calcification

-valve projeting into lumen

most common complication

anastomotic and vein stenosis

Mild-to-moderate stenosis will decrease volume flow to

500-800

severe stenosis will decrease volume flow to

<500 ml/min

Venous stenosis appears as

echogenic intraluminal lesion with flow

reduction on B-mode imaging.