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VASC 335 > Hemodialysis & Fistulas > Flashcards

Hemodialysis & Fistulas Flashcards

1
Q

What is hemodialysis?

A

The removal of certain elements from the blood through a semi-permeable membrane while being circulated outside the body.

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2
Q

When is hemodialysis needed?

A

End stage renal disease (ESRD)

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3
Q

What does hemodialysis require? (2)

A
  1. High flow

2. Easily accessed vessel that can tolerate multiple punctures with catheters

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4
Q

How is the high flow situation created for dialysis? (2)

A
  1. AV fistula surgically created by connecting an artery to a vein (high pressure flow from artery to vein)
  2. AVG (graft) surgically inserted to connect artery and vein
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5
Q

What are the two methods of AVG?

A
  1. Prosthetic graft

2. Using a vein as a conduit

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6
Q

What has a high prevalence with dialysis graft patients?

A

Subclavian vein thrombus

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7
Q

What are the different types of grafts?

A
  1. Loop

2. Straight

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8
Q

What are the methods for hemodialysis with fistula evaluation and what is the preferred method?

A
  1. Duplex ultrasound (preferred)
  2. Arteriography (x-ray)
  3. Fistulography (x-ray)
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9
Q

What are the indications for a hemodialysis/fistula exam? (13)

A
  • Abnormal measurements during dialysis session
  • Extremity symptoms
  • UE swelling
  • Decrease in bruit/thrill in conduit
  • Evaluation of AVF maturity
  • Pulsatile mass
  • Thromboses conduit/access
  • Peri-graft mass
  • Decreased thrill/pulse
  • Suspected steal
  • Infection
  • Bleeding
  • Post revision follow-up
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10
Q

What are AVG’s evaluated for on Duplex exams? (6)

A
  • Stenosis
  • Thrombosis
  • Aneurysms
  • Pseudoaneurysms
  • Hematomas
  • Arterial steal from hand
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11
Q

What is the most common cause of failure in the 1st month of AVG’s?

A

Thrombosis of graft

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12
Q

What transducer is preferred for graft analysis?

A

10-12 MHz

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13
Q

What is the patient position for AVG duplex exam?

A

Supine

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14
Q

What is the sample gate opened for in the duplex exam?

A

Volume flow calculation

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15
Q

What is the volume flow calculation?

A

Volume flow (Q) ml/min = TAV(time average velocity) x area x 60

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16
Q

Where should PSV be recorded in a AVG duplex exam? (5)

A
  • native artery prox
  • arterial anastomosis
  • graft
  • venous anastomosis
  • venous outflow
17
Q

What is important to sample with an AV fistula?

A

2-3 sites distal to the arterial anastomosis

18
Q

What does reversal in the ulnar or radial artery indicate?

A

That the graft is stealing blood from the hand due to a lower pressure upstream (stenosis) from the wrist

19
Q

Why may a steal from the hand arteries (ulnar or radial) be common in a graft?

A

Due to the pressure diff between the artery and vein and the narrowing (stenosis) of a graft, high flow is directed into the graft towards the low pressure vein from the distal arteries (reversal).

20
Q

What is more frequently used to determine the severity of stenosis than PSV’s?

A

Peak Systolic Velocity Ratio’s (V2/V1)

21
Q

What do normal hemodialysis waveforms display? (3)

A
  • High-flow states
  • Low resistance
  • Increased PSV and EDV
22
Q

What depth is required for successful access for dialysis?

A

Less than 5 mm from skins surface

23
Q

What PSV is considered normal for both fistulas and grafts?

A

PSV < 400 cm/s

24
Q

What is the normal PSV and EDV for dialysis grafts?

A

PSV: 100-400 cm/s

EDV: 60-200 cm/s

25
Q

What is the normal PSV in the outflow vein of a dialysis graft?

A

30-100 cm/s

26
Q

What is the normal PSV ratio in a dialysis graft?

A

<2.0

27
Q

What is a normal PSV ratio in a dialysis fistula?

A

PSV ratio < 2.0

28
Q

What is considered a normal PSV ratio in the distal anastomosis of a dialysis fistula?

A

<3.0

29
Q

What is the optimal dialysis graft performance (volume flow)?

A

> 800mL/min

30
Q

What is the optimal fistula performance (volume flow)?

A

> 500 mL/min

31
Q

What arterial resistance is expected above and below the anastomosis?

A

Above = low resistance

Below = High resistance

32
Q

What conditions indicate abnormal flow in a dialysis graft?

A
  • decreased lumen
  • evidence of stenosis
  • decreased pulsatility, phasicity, spontaneity
33
Q

What PSV and PSV ratio indicates a significant (>50%) stenosis at the venous anastomosis of a prosthetic graft?

A

PSV > 400 cm/s AND a PSV ratio of ≥ 1.9 together

34
Q

What PSV ratio indicates abnormal arterial inflow or venous outflow of an AV fistula?

A

> 2.0 indicates a significant stenosis

35
Q

What PSV ratio of a AVF anatomosis indicates a significant stenosis?

A

> 3.0

36
Q

What is considered suboptimal graft performance?

A

Volume flow < 800 mL/min

37
Q

What is considered suboptimal fistula performance?

A

Volume flow < 500 ml/min

38
Q

Review images

A

….

VASC 335 (9 decks)

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