50–100g puncture force, 0.5–1.0N-the "pain" of AVF needles isn't a single event, but the accumulation of 1,500 instances. The material states that AVF needles have a "penetration force due to larger size and thicker wall, typically around 50–100 grams (0.5–1.0 N)." For comparison: a 25G hypodermic needle is about 30–50 g, a 21G is approximately 40–70 g, while a 17G AVF needle ranges from 50–100 g-indeed significantly "stiffer." However, the pain experienced by dialysis patients isn't just about "how painful one single insertion is," but rather the cumulative effect of the same fistula being punctured three times weekly for ten years: fibrosis of the skin around the fistula, heightened sensitivity of nerve endings at the puncture site, and variations in nursing technique.

Four Manufacturing Variables Affecting Pain Perception

• Bevel angle: For 17G AVF needles, a common range is 15°–20° (Rochester). A sharper bevel reduces puncture force and pain, but if too sharp (<15°), it may penetrate the venous wall with a "pop," increasing hematoma risk. An angle of 18–20° offers a balanced compromise; Manners' standard products typically use 18–19°.
• Needle shaft surface roughness (Ra): The material undergoes electrolytic polishing and ultrasonic cleaning, reducing Ra from 0.4 to 0.1–0.15. When the needle remains in the fistula for four hours, higher Ra values can cause the endothelium to "catch" on the shaft, resulting in noticeable tearing upon removal-patients often report that "removal hurts more than insertion," which is frequently due to inadequate Ra control.
• Silicone coating: While the material does not mention silicone coating for AVF needles, high-end European and American brands (e.g., Terumo SV, JMS Soft Touch) apply silicone coatings to the needle shaft, further reducing insertion force by 15–20%. Currently, about 70% of domestic OEMs do not implement this, primarily due to challenges in detecting EO residue after silanization when connecting Luer lock fittings-silicone oil interferes with bonding between PVC dialysis tubing and Luer connectors, requiring low-molecular-weight silicone oil combined with plasma spraying instead of dip coating.

Transition radius at the needle wing: When nurses secure the needle and the patient moves slightly, the area where the needle shaft meets the skin can cause pressure or "pinching." A fillet radius of R0.5 or greater at the base of the needle wing can reduce complaints of "discomfort during dwell" by 20–30%.

"Fistula Memory" from Repeated Punctures

The buttonhole technique: patients fear "rough needle surface → skin debris carried in and out of the tunnel with each insertion → tunnel infection." Therefore, electropolished Ra 0.1 is not just a luxury for buttonhole users-it's a necessity. In European markets where the buttonhole technique is widely adopted (such as Nordic countries and the Netherlands), an AVF needle with Ra 0.15 is the minimum requirement; needles above Ra 0.25 are excluded.

?? For OEM: In the "patient experience" parameter table for AVF needles, in addition to gauge/length, please complete the four columns-needle tip bevel angle, needle shaft Ra, whether siliconized, and wing corner radius. The Japanese line and European eyelet method markets will verify each column individually.