Cannulation Decision After Arterial Infiltration in a Mature AV Fistula
Mr. A is a 58-year-old man on thrice-weekly hemodialysis through a left brachiocephalic arteriovenous fistula created 9 months ago. Two days ago the arterial needle infiltrated during treatment; the area remains tender with a 3 × 4 cm ecchymosis over a 1.2 cm aneurysm. Today the fistula has a palpable thrill and pulse augmentation, and the skin is intact. Pre-dialysis BP is 148/86 mmHg, weight 72.4 kg, target 71.0 kg. His prior blood flow was 280 mL/min with venous pressure 170 mmHg, and the last single-pool Kt/V was 1.25. Only 15-gauge needles are stocked; chairside ultrasound is unavailable. The patient asks staff to use 'the same spot as always' because it is easier. The unit is busy and the nurse is considering a single-needle treatment to save time. His last two sessions were shortened by 20 minutes because of machine alarms.
1. What findings must the nurse confirm before cannulating this fistula today, and what would make you defer cannulation and arrange alternative access?
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Before cannulation, inspect and palpate the whole outflow tract: thrill, pulse augmentation, compression time, skin integrity, aneurysm size, ecchymosis borders, tenderness, distal radial pulse, hand color, edema, and any signs of infection such as warmth, erythema, or drainage. Compare with the previous session.
Defer today if there is an expanding hematoma, absent thrill, severe pain over the proposed segment, skin breakdown, purulent drainage, or no palpable straight segment away from the aneurysm. The ecchymosis is a contraindication to cannulating that segment, not necessarily to the whole fistula. If no safe site exists, arrange temporary catheter placement or medical review rather than forcing a needle. Single-needle dialysis is not a safe time-saving substitute; it often reduces clearance and does not solve the access problem.
2. If the fistula is used, specify a safe cannulation plan: needle selection, sites, machine settings, and intra-treatment stopping rules.
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If using the fistula, choose 15-gauge needles and rope-ladder rotation. Place the arterial needle at least 2–3 cm from the anastomosis and well away from the 3 × 4 cm ecchymosis and aneurysm; place the venous needle downstream and separate from the arterial site. Avoid blind deep cannulation.
Start blood flow at 250 mL/min and increase to 300 mL/min only if arterial and venous pressures remain stable; set narrow pressure alarms. Program the prescribed ultrafiltration and monitor the access every 15 minutes for pain, swelling, blood leak, or pressure change. Stop immediately if a hematoma develops; apply pressure without occluding the fistula, use the other needle for return if possible, and do not use the infiltrated site. Do not exceed 300 mL/min merely to finish early.
3. How would you document and communicate this decision?
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Document the pre-cannulation assessment, exact sites considered and avoided, needle gauge, blood flows, pressures, and patient statements. Record the prior infiltration and today's plan in the dialysis record and handover. Tell the patient plainly why 'the same spot' is unsafe: risk of aneurysm, stenosis, and access loss.
Notify the nephrologist and access coordinator, and request access surveillance such as ultrasound or fistulogram if the usable segment is limited. Complete an incident report for the previous infiltration. Reassess at the next session; if bruising persists or the thrill changes, escalate before cannulation.