CHBT Vascular Access and Cannulation Basics 1 — Questions and Answers
Question 1: Which type of vascular access is considered the 'gold standard' for long-term hemodialysis due to its superior patency and lower infection risk?
- Arteriovenous fistula (AVF) (Correct answer)
- Arteriovenous graft (AVG)
- Tunneled central venous catheter (CVC)
- Non-tunneled temporary catheter
Correct answer: Arteriovenous fistula (AVF)
The AVF is the preferred access because it uses the patient's own vessels, resulting in lower rates of infection, thrombosis, and hospitalization compared to grafts or catheters. It also has the longest functional lifespan.
The AVF is the preferred access because it uses the patient's own vessels, resulting in lower rates of infection, thrombosis, and hospitalization compared to grafts or catheters. It also has the longest functional lifespan.
Question 2: What is the 'rope ladder' cannulation technique?
- Rotating needle insertion sites along the entire length of the access, distributing puncture trauma evenly (Correct answer)
- Inserting two needles at the same site every session to maximize flow
- Using a guidewire to thread the needle into the access vessel
- Placing needles perpendicular to the vessel wall to reduce aneurysm risk
Correct answer: Rotating needle insertion sites along the entire length of the access, distributing puncture trauma evenly
The rope ladder technique rotates insertion sites systematically along the graft or fistula, preventing aneurysm formation at any single point by distributing puncture trauma over the full access length.
The rope ladder technique rotates insertion sites systematically along the graft or fistula, preventing aneurysm formation at any single point by distributing puncture trauma over the full access length.
Question 3: Before cannulating an arteriovenous fistula, which assessment is essential?
- Auscultating for a bruit and palpating for a thrill to confirm access patency (Correct answer)
- Taking the patient's blood pressure in the fistula arm
- Applying a tourniquet above the fistula for 5 minutes
- Comparing the fistula arm temperature to the opposite arm
Correct answer: Auscultating for a bruit and palpating for a thrill to confirm access patency
A bruit (audible flow sound by stethoscope) and thrill (palpable vibration) confirm the fistula is patent and functioning. Absence of either may indicate thrombosis or stenosis and must be reported before cannulation.
A bruit (audible flow sound by stethoscope) and thrill (palpable vibration) confirm the fistula is patent and functioning. Absence of either may indicate thrombosis or stenosis and must be reported before cannulation.
Question 4: What is the minimum maturation time typically required for an AVF before it can be used for hemodialysis?
- At least 4–6 weeks (ideally 3–4 months) (Correct answer)
- 7–10 days post-creation
- Immediately after surgical creation
- 6–12 months without exception
Correct answer: At least 4–6 weeks (ideally 3–4 months)
An AVF requires a minimum of 4–6 weeks to mature (arterialization of the vein wall), but 3–4 months is preferred to allow adequate vessel dilation and wall strengthening for reliable cannulation.
An AVF requires a minimum of 4–6 weeks to mature (arterialization of the vein wall), but 3–4 months is preferred to allow adequate vessel dilation and wall strengthening for reliable cannulation.
Question 5: What is 'infiltration' in the context of vascular access cannulation?
- Leakage of blood into surrounding tissue when a needle punctures through or outside the vessel wall (Correct answer)
- Introduction of air into the blood circuit through a loose needle connection
- Backflow of dialyzed blood into the arterial needle
- Contamination of the access site with skin bacteria during insertion
Correct answer: Leakage of blood into surrounding tissue when a needle punctures through or outside the vessel wall
Infiltration (also called hematoma) occurs when the needle is misplaced outside the vessel, causing blood to leak into surrounding tissue. The needle must be removed, firm pressure applied, and the treatment may need to be postponed.
Infiltration (also called hematoma) occurs when the needle is misplaced outside the vessel, causing blood to leak into surrounding tissue. The needle must be removed, firm pressure applied, and the treatment may need to be postponed.
Question 6: Why should blood pressure never be measured in the arm containing an arteriovenous fistula?
- Cuff compression can restrict fistula blood flow and potentially cause thrombosis (Correct answer)
- The bruit creates noise that interferes with Korotkoff sounds, giving inaccurate readings
- The fistula creates artificially elevated pressures due to high flow
- Blood pressure measurement is prohibited in any arm with a chronic wound
Correct answer: Cuff compression can restrict fistula blood flow and potentially cause thrombosis
BP cuff inflation compresses the fistula, interrupting high-volume flow and risking thrombosis. Additionally, venipuncture, IV lines, and tight clothing are also contraindicated in the fistula arm.
BP cuff inflation compresses the fistula, interrupting high-volume flow and risking thrombosis. Additionally, venipuncture, IV lines, and tight clothing are also contraindicated in the fistula arm.
CHBT Vascular Access and Cannulation Basics 1
Which type of vascular access is considered the 'gold standard' for long-term hemodialysis due to its superior patency and lower infection risk?