Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PGY 4 > Access > Flashcards

Access Flashcards

1
Q

What is the minimum vein diameter for forearm access?

A

2-2.5 mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What creatinine clearance should ESRD be referred to vasc surgeons for access?

A

Cr clearance < 25 ml/min (2005 SVS guidelines)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How long before IHD should you create access?

A

6 months for autogenous

3-6 weeks for graft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Name 7 patient factors that can affect patency of access

A

1 - age

2 - smoking

3 - diabetes

4 - anemia

5 - parathyroid hormone

6 - certain medications

7 - atherosclerotic disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

In elderly patients (>50) - what would be your first choice for AV access?

A

Upper arm autogenous or prosthetic. Distal radial have poorer patency and given short life expectancy you want to have reliable access sooner.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In diabetics - why is it advantageous to have as distal access as possible?

A

Higher risk of steal in diabetic patients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Given calcification and atherosclerosis - should you offer proximal or graft as first line for diabetics?

A

No - increased risk of steal with proximal. No difference in abilty to create autogenous fistulas despite increased calcification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What medications can improve access patency?

A

Antiplatelet, ACE inhibitors for autogenous, Calcium channel blockers for grafts, ARBs but no consensus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the minimum arterial requirements for AV access?

A

2 mm, patent palmar arch, no pressure gradient between bilateral upper extremities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What access flow rate should prompt further investigation?

A

< 600 mL/min or < 1000 mL/min with 25% reduction over 4 months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are 7 access complications recognized by the 2006 KDOQI guidelines?

A

1 - infection

2- neuropathy

3 - seroma

4 - pseudoaneurysm/aneurysm

5-access related hand ischemia

6 - venous hypertension

7 - bleeding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does anemia contribute to increased bleeding in ESRD patients?

A

Low hematocrit causes an increase in NO activity which causes vasodilation and platelet inhibition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does uremia affect platelets (3 ways)?

A

1) Reduced expresion of GPIb which impairs platelet adhesion to subendothelium
2) Conformational change of GP2a3b which inhibits fibrinogen binding and platelet aggregation
3) Decrease in dense granules reduces storage of platelet ADP and serotonin and creases endothelial production of prostacyclin which inhibits plately activation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Name 3 reasons ESRD are prone to bleeding

A

1) Uremia platelet dysfunction
2) Medications - 20% have afib and on anticoag, betalactams can cause platelet dysfunction at high levels
3) thrombocytopenia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do antibiotics increase risk of ESRD patients bleeding?

A

Betalactams (penicillins/cephalosporins) have long half lives and only partially cleared by dialysis. At high concentrations they can cause platelet dysfunction. At very high concentrations it can alter antithrombin III and act like heparin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name 4 ways of managing bleeding post access surgery

A

1 - DDAVP

2 - Platelet transfusion (only lasts 4 -5 h because platelets become dysfunctional in a uremic environment)

3 - Cryoprecipitate - rich in fibrinogen, vWF, factor 8. Works within minutes, effect max at 4-12 h and lasts up to 24 h

4 - Protamine if on heparin during surgery or after dialysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does DDAVP help with access related bleeding (3 ways)?

A

DDAVP is a human made form of ADH.

1) It induces rapid release of autologous vWF and 2) factor 8 and 3) transiently decreases activity of protein C.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Name 4 ways of optimizing patients bleeding risk for elective access surgery

A

1) Check hemoglobin - <100 in 20% of ESRD patients. May require EPO to induce erythrpoesis and correct anemia but takes several weeks to show effect.
2) Schedule surgery 24 after dialysis
3) DC antiplatelets 1 week prior
4) Consider conjugated estrogens (increase vWF synthesis, reduce protein S and NO and correct bleeding time)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How does EPO help with bleeding in ESRD patients (2 ways)?

A

1) induces erythropoieses thus correcting anemia
2) increases platelet expression of GP2b3a and enhances platelet aggregation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does estrogen help with bleeding in ESRD patients?

A

1) Increase vWF synthesis
2) Reduces protein S
3) Reduces NO

Requires IV treatment for 5 consecutive days or transdermal 2 weeks prior

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the 3 recommended SVS reporting standards for classifying access infections?

A

1) early < 30 d vs late
2) culture positive or neg
3) site (anastomotic, mid AV access, outflow veins)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What organism is most often responsible for access related infections?

A

Staph aureus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the probability of developing an access related infection in 1 year for autogenous AV fistulas versus prosthetic grafts?

A

5% vs 20%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a risk of the buttonhole technique?

A

Increased risk of infection compared with rope ladder or area techniques

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How should you treat access related infections?

A

Broad spec antibiotics - vanco and gent chosen because of ease of dosing and spectrum. In centres with low MRSA, can use ancef.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the specific anatomic requirements for an autogenous femoral vein transposition (eg GSV) for access?

A

1) Patent femoral vein > 3-6 mm (both written?)
2) Patent, noncalcified superficial femoral artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Who is autologous femoral vein transposition accesses ideally suited for (3 groups)?

A

1 - Pediatric/young healthy patients

2 - Hypercoagulable patients with no other access options

3 - Patients at high risk for infection (poor hygiene, immunosuppressed, previous access infections)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are 4 contraindications to autogenous femoral vein transposition for dialysis access?

A

1 - obese thigh

2 - “medically fragile”/elderly

3 - Temporary catheter sites not readily available

4 - Pts at high risk of access-related ischemia of the lower extremity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What 2 anatomic requirements are there for prosthetic midthigh loop femoral-femoral access

A

1 - patent femoral vein or common femoral vein

2 - patent SFA or CFA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Who are ideally suited for prosthetic midthigh loop femoral femoral AV access?

A

elderly with significant comorbidities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are contraindications to prosthetic midthigh loop femoral-femoral access (2 types)?

A

1 - high risk of infection (immunosuppressed, prev infection, hygiene)

2 - morbid obese

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What are the anatomic requirements for prosthetic chest wall access for dialysis (2)?

A

1 - Patent axillosubclavian artery and vein

2 - Patent central vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Who is prosthetic chest wall access for dialysis ideally suited for?

A

1 - Morbid obese

2-Pts at high risk of access related limb ischemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are the anatomic requirements for tunneled dialysis catheter?

A

Patent central vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Who are tunneled catheters ideally suited for (2)?

A

1 - “Medically fragile” patients with life expectancy < 6 months

2 - Pts who failed all other access options

36
Q

What are the anatomic requirements for Hemoaccess Reliable Outflow vascular devices?

A

1 - Guidewire access to a patent central vein

2 - Brachial artery > 3mm

37
Q

What type of patients are ideally suited for a HeRO (2)?

A

1) Central venous stenosis/occlusion that precludes upper extremity autogenous or prosthetic access options
2) Patients otherwise relegated to tunneled line

38
Q

What are contraindications to HeRO graft?

A

Active infection

sBP < 100

EF < 20%

39
Q

What type of access is this?

A

Brachioaxillary with transposed autogenous femoral vein

40
Q

What are the 2 year patency rates of brachiobasilic transposition access?

A

~ 50% (1 year varies 40-92% depending on source)

41
Q

What time interval should you have between 1st and 2nd stages of a brachiobasilic transposition?

A

4-6 weeks

42
Q

When would you consider a single stage brachiobasilic transposition procedure?

A

If the basilic vein > 4mm

43
Q

When performing a 2nd stage brachiobasilic transposition, what nerves are at risk?

A

medial antebrachial cutaneous and median

44
Q

After the second stage of a brachiobasilic vein transposition, when can it be accessed?

A

When wounds have healed, usually in 3 weeks

45
Q

What is a necklace access?

A

axillary artery to contralat jugular vein

46
Q

What is an advantage and disadvantage of chestwall access compared with lower extremity?

A

Pro: Lower infection rates, better for obese patients

Con: if graft becomes infected and needs removal, proximal control of axillary artery is challenging.

47
Q

Where does access related neointimal hyperplasia occur in prosthetic and autogenous AV access?

A

1 - Prosthetic: outflow anastomosis

2 - Autogenous anywhere along the outflow vein

Also: central venous on the ipsilateral side.

48
Q

What is the most common measure of access function? What is an acceptable value?

A

Kt/V

K = rate of clearance of urea (calculated from the pre and post dialysis measurements)

t = duration of dialysis

V = urea distribution volume

KtV is generally monitored to ensure > 1.2

49
Q

What is dialysis “recirculation”

A

Retreatment of blood already filtered by dialysis machine. Can result when afferent needle pulls blood that has just been returned to the patient via efferent needle.

50
Q

Name 4 causes of recirculation problems with IHD

A
  1. Venous outflow stenosis - classic problem of prosthetic grafts
  2. Arterial inflow stenosis - both needles are distal to the stenosis - can result in complete collapse of the outflow vein. A problem seen with autogenous AV access
  3. Inadquate separation of cannulation needle
  4. Puncturing of psuedoaneurysms which are sufficiently large that they have stagnant flow within them.
51
Q

Name 3 ways of clinically determining access failure.

A
  1. Thrill not detectable or pulse present near the venous outflow
  2. Collateral veins in shoulder and anterior chest wall or upper extremtiy edema
  3. High venous pressures resulting in long access bleeding times
52
Q

Name 2 ways of determining failing access during dialysis

A
  1. Venous pressure > 50% of MAP
  2. Flow measurement. (Bolus isotonic saline dilutes blood and U/S velocity, sensors registers an indicator curve as saline passes through the blood lines to calculate the flow rate)
53
Q

What is the most preferred site for tunneled HD line placement and why?

A

Right IJ - best patency likely due to less kinking

54
Q

Name 5 causes for prolonged access site bleeding

A
  1. Uremia related platelet dysfunction
  2. Anemia related increased NO causing vasodilation/platelet inhibition
  3. Beta lactams at high doses cause platelet dysfunction and at very high doses affect ATIII
  4. 20% of patients have afib and on anticoag
  5. Venous outflow stenosis
55
Q

How does uremia cause prolonged bleeding? (3 mechanisms)

A
  1. Reduces expression of glycoprotein 1b which impairs platelet adhesion to subendothelium
  2. Conformational change in GP 2b3a which inhibits fibrinogen binding and platelet aggregation
  3. Decreased content of dense granules thus reduces storage of ADP and serotonin which in turn inhibits platelet activation
56
Q

How does DDAVP treat bleeding in uremic patients (3 ways)?

A
  1. Induces rapid release of autologous vWF
  2. Induces rapid release of autologous Factor 8
  3. Transiently decreases activity of protein C.
57
Q

What is a grade 3 access infection?

A

Loss of limb

58
Q

What is a grade 2 access infection?

A

Loss of AV access because of ligation, removal and bypass

59
Q

What is a grade 1 access infection?

A

Resolved with antibiotic treatment

60
Q

What is a grade 0 access infection?

A

No infection

61
Q

What is the most common access-related infection bacteria?

A

Staph aureus

62
Q

What is the risk of access infection at 1 year: autologous vs. graft?

A

4.5% vs 19.7%

63
Q

Why is the “button hole” access technique worse than the “rope ladder”?

A

Higher infection rate. This is due to inappropriate use of sharp needles after tract developed, inadequate use of disinfecting agents and incomplete scab removal.

64
Q

Which antibiotics are used for access related infections?

A

Typically vanco and gentamicin because its broad spec and easy to dose.

If there is a low prevalence of S. Aureus - ancef may be used.

65
Q

How do you treat a AV access graft infection?

A

Broad spec antibiotics + local resection if possible. Salvage is most frequently feasible when infection involves the midportion of the graft. A new graft can be tunneled through clean tissue planes.

(Anastomotic infection requires complete graft excision to prevent disruption/hemorrhage)

66
Q

Name 4 treatment options for AV pseudoaneurysms

A
  1. Interposition graft/bypass around lesion
  2. Autogenous can be converted to graft “graftula” where arterial anast is kept and venous anast new
  3. Fistula reduction with resection of portion of vein wall (10 mm rubber catheter used as a sizing dowel)
  4. Endovascular self expanding covered stent graft.
67
Q

What is the rate of steal with autogenous brachial access?

A

4-8%

68
Q

What is the rate of steal with autogenous wrist access?

A

1-2%

69
Q

What is a Grade 3 steal?

A

Severe - ischemic pain at rest, tissue loss

70
Q

What is a Grade 2 steal?

A

Moderate - intermittent ischmeia only during dialysis, claudication

71
Q

What is a Grade 1 steal?

A

Mild - cool extremity, few symptoms, flow augmentation with access occlusion

72
Q

What is a Grade 0 steal?

A

No symptoms

73
Q

When do you have to intervene for steal?

A

Grade 2 sometimes needed (claudication/ischemia during dialysis), Grade 3 (rest pain and tissue loss) mandatory to intervene.

74
Q

Name 2 other conditions on differential for steal

A
  1. Carpal tunnel syndrome
  2. Ischemic monomelic neuropathy
75
Q

How do you treat grade 1 mild steal (transient mild symptoms)

A
  1. Serial examinations
  2. Reduce antihypertensive medications
  3. Re-warm
76
Q

Name 6 treament options for severe steal.

A
  1. Banding/flow limiting procedures
  2. Proximalization of arterial inflow
  3. Revision using distal inflow (RUDI)
  4. Distal revascularization with interval ligation (DRIL)
  5. Angioplasty
  6. Ligation (last resort)
77
Q

What is the MILLER procedure? Why is it used?

A

Minimally invasive limited ligation endoluminal assisted revision

A 4 or 5 mm balloon placed percutaneously as a sizing dowel, cut down on anastomosis, secure a suture around the access with a balloon inflated.

Difficult to determine how much to stenose access to maintain patency but relieve ischemic steal symptoms and anesthesia can make intra-op flow measurements inaccurate.

78
Q

What are 3 risks of DRIL procedure

A
  1. High mortality - 6.8%
  2. Invasiveness/wound complication rates of 9-19%
  3. Hand perfusion is dependent on the bypass
79
Q

What is the best treatment option when steal is associated with low or normal flows (happens in 1/3 of steal patients)?

A

Likely inadequate collaterals due to atherosclerotic disease - best treated via revascularization - DRIL, proximalization, or angioplasty

80
Q

Which treatment options are well suited for high flow steal (autogenous > 800 mL, prosthetic > 1200 mL/min)

A

Banding and RUDI

81
Q

Which treatment options for steal require an autogenous conduit?

A

RUDI and DRIL. Proximalization typically uses prosthetic.

82
Q

What is the central vein stenosis rate for IJ catheters? What about subclavian vein? Any theories as to why?

A

IJ 10%

Subclavian 40-50%

Maybe due to endothelial repetitive trauma with cardiac and respiratory cycles

83
Q

What does KDOQI guidelines recommend for treating central vein stenoses/occlusions?

A

Asymptomatic - no treatment

Symptomatic - PTA

Ligation last resort.

84
Q

What is the 6 month and 1 year patency of central vein stenoses after angioplasty?

A

Poor - 20-50%, 12-40%

85
Q

What is the most common cause of neuropathy in dialysis patients?

A

Uremia

PGY 4 (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions