CCHT - Certified Clinical Hemodialysis Technician Vascular Access and Cannulation 1

Question 1

What is the recommended angle of needle insertion when cannulating a mature arteriovenous fistula?

Accepted Answer

25–35 degrees

Answer

A 25–35 degree insertion angle allows the needle to enter the vessel lumen cleanly without going through the back wall. Shallower angles risk staying subcutaneous, while steeper angles increase the risk of posterior wall puncture and infiltration.

Question 2

Which of the following is the earliest and most reliable sign of needle infiltration during a hemodialysis treatment?

Accepted Answer

Localized swelling and pain at the needle insertion site

Answer

Infiltration occurs when the needle tip exits the vessel lumen into surrounding tissue. The immediate result is extravasation of blood or dialysate, causing localized swelling, firmness, and pain at the site. Pressure alarms may change secondarily but are not as specific or early an indicator.

Question 3

What is the minimum recommended distance between the arterial and venous needles during AV fistula cannulation to minimize recirculation?

Accepted Answer

5 cm

Answer

Placing needles at least 5 cm (approximately 2 inches) apart prevents recirculation, which occurs when already-dialyzed blood is immediately re-drawn into the arterial needle. Recirculation reduces treatment adequacy and Kt/V.

Question 4

According to the 'Rule of 6s,' which set of criteria indicates that an AV fistula is mature and ready for cannulation?

Accepted Answer

Flow >600 mL/min, diameter ≥6 mm, depth ≤6 mm, maturation ≥6 weeks

Answer

The Rule of 6s states a fistula is mature when it has blood flow exceeding 600 mL/min, a vessel diameter of at least 6 mm, is no more than 6 mm below the skin surface, and has had at least 6 weeks to mature. These thresholds help ensure reliable cannulation and adequate dialysis delivery.

Question 5

Which type of hemodialysis vascular access carries the highest risk of bloodstream infection?

Accepted Answer

Tunneled cuffed central venous catheter

Answer

Tunneled cuffed central venous catheters (CVCs) have the highest infection risk among hemodialysis accesses because the catheter provides a direct conduit from the skin surface into the central venous system, bypassing natural skin and vascular barriers. Native AV fistulas have the lowest infection rates and are the preferred access.

CCHT - Certified Clinical Hemodialysis Technician Practice Test

CCHT - Certified Clinical Hemodialysis Technician Practice Test

CCHT - Certified Clinical Hemodialysis Technician Vascular Access and Cannulation 1