# AI instructs to cannulate an arteriovenous fistula for hemodialysis without verifying thrill or using tourniquet, risking infiltration and access loss

- **ID:** `medical/hemodialysis-av-fistula-cannulation-error`
- **Domain:** medical
- **Category:** runtime_error
- **Error Code:** `AVF-CANN-001`
- **Verification:** ai_generated
- **Fix Rate:** 85%

## Root Cause

Cannulating an AV fistula without first confirming patency via thrill/pulse and without proper tourniquet technique can cause infiltration, hematoma, or pseudoaneurysm, leading to permanent access loss in dialysis patients.

## Workarounds

1. **Before cannulation, palpate the fistula for a continuous thrill and auscultate for a bruit. Apply tourniquet 5-10 cm proximal to the anastomosis (not above it). Use a 15G or 16G needle at a 25-30° angle with bevel up. Confirm flashback of pulsatile blood before advancing.** (92% success)
   ```
   Before cannulation, palpate the fistula for a continuous thrill and auscultate for a bruit. Apply tourniquet 5-10 cm proximal to the anastomosis (not above it). Use a 15G or 16G needle at a 25-30° angle with bevel up. Confirm flashback of pulsatile blood before advancing.
   ```
2. **If thrill is weak, perform a 'hand-grip exercise' (patient squeezes a stress ball for 30 seconds) to augment flow before cannulation.** (78% success)
   ```
   If thrill is weak, perform a 'hand-grip exercise' (patient squeezes a stress ball for 30 seconds) to augment flow before cannulation.
   ```
3. **Use ultrasound guidance to visualize fistula depth and diameter, especially for deep or tortuous accesses. Select needle based on measured depth (e.g., 1.5-inch needle for depth >1 cm).** (95% success)
   ```
   Use ultrasound guidance to visualize fistula depth and diameter, especially for deep or tortuous accesses. Select needle based on measured depth (e.g., 1.5-inch needle for depth >1 cm).
   ```

## Dead Ends

- **Apply tourniquet above the fistula to increase vein size for easier cannulation** — Tourniquet should be applied below the fistula (distal) to avoid occluding arterial inflow; proximal tourniquet can reduce flow and cause access collapse. (85% fail)
- **Use a larger gauge needle (14G) to ensure adequate blood flow during dialysis** — Needle gauge must match fistula maturity and flow; large needles in immature fistulas increase infiltration risk. Standard is 15G or 16G for initial use. (75% fail)
- **Cannulate immediately after needle insertion without checking for backflow** — Without confirming arterial flashback or pulsatile flow, the needle may be in the vein wall or subcutaneous tissue, causing infiltration. (90% fail)