In the field of medical devices, standardized products meet general needs, while customized designs aim to overcome specific clinical challenges or enhance specific performance. For AVF puncture needles, with the continuous improvement of hemodialysis technology and the increasing requirements for patient comfort, innovative customized design for their core function - establishing an efficient and stable extracorporeal blood flow channel - has become an important development direction in the industry. This article will focus on the customized design of AVF needles, particularly through structural innovation to optimize the hemodynamic performance, thereby improving the dialysis efficacy and patient safety.

I. Limitations of Traditional Design and Customization Requirements

The standard AVF needle usually has a single elliptical or circular opening at the tip of the needle's inclined surface. Ideally, this design functions properly. However, in clinical practice, especially in cases of high blood flow dialysis or when the patient's own vascular condition is poor, the single-hole design may exhibit limitations:

• Pinhole adhesion to the wall: Under the suction effect of the blood pump, the pinhole may be adhered to the inner wall of the fistula vessel, causing a sudden interruption or fluctuation in blood flow, which affects the adequacy of dialysis and may trigger an alarm from the hemodialysis machine.
• High shear force in blood flow: When blood is rapidly extracted from a larger vascular cavity through a single, relatively small pinhole, a high shear force area is formed near the pinhole, which may increase the risk of red blood cell destruction (hemolysis).
• Potential thrombosis risk: Turbulent or stagnant flow areas are formed in the blood flow near the pinhole, which may increase the risk of local platelet activation and fibrin deposition.

These clinical pain points have led to the demand for more optimized AVF needles, prompting manufacturers to shift from being "standard product suppliers" to "customized solution partners".

II. Core Innovation: Multiple Side Holes and Laser Slotting Technology

Currently, the core breakthrough in the customized design of AVF needles lies in changing the opening structure at the needle tip, from a "single entry point" to "multiple entry points or distributed entry points". This is mainly achieved through the advanced 5-axis laser cutting technology.

• Multi-hole design: On the side wall of the needle tube behind the needle tip's inclined surface, the laser precisely cuts out multiple (usually 2-4) additional side holes. The advantages of this design are:
• Anti-sticking to the vessel wall: Even if the main needle hole accidentally sticks to the vessel wall, the side holes can remain open and continuously draw blood, significantly improving the stability of blood flow and reducing treatment interruptions.
• Reduced flow rate and shear force: The total blood drawing area increases, and under the same blood flow volume, the average flow velocity of blood passing through each hole decreases, thereby reducing the damage to blood cells caused by high shear force.
• Diversified blood flow: Blood enters the needle tube from multiple directions, the flow field becomes smoother, reducing turbulence and stagnant areas, and theoretically can lower the risk of local thrombosis.
• Spiral grooves or long strip window design: This is a further optimization of fluid mechanics. Using a 5-axis laser to cut spiral-arranged grooves or long strip-shaped windows in the needle tip section. This design not only provides multiple entrances, but more importantly, creates a more fluid-dynamic guiding flow path. It can guide blood from the vessel into the needle tube in a gentler manner, further smoothing the blood flow, minimizing flow separation and vortex generation, and achieving the optimal hemodynamic performance.

III. Synergistic Benefits and Considerations of Customized Design

The customized hemodynamic optimization design has brought about various synergistic benefits:

• Enhance dialysis efficiency: Stable high blood flow is the key to ensuring adequate dialysis. The anti-adhesion design ensures the continuity of blood flow during treatment, which helps achieve the preset dialysis dose.
• Enhance patient safety: Reducing hemolysis means less destruction of hemoglobin, protecting the patient's blood resources; optimizing the flow field may reduce clot activation, which is also beneficial for maintaining the filtration function of the dialyzer.
• Improve patient experience: Reducing machine alarms, interventions, and prolonged treatment times caused by poor blood flow indirectly improves the treatment comfort of patients.
• Of course, customized design also requires comprehensive consideration. More complex structures impose higher requirements on manufacturing precision (such as tolerance control in laser cutting, deburring processes) and costs. Moreover, any new design needs to be verified for safety and effectiveness through rigorous fluid dynamics tests, in vitro simulation experiments, and final clinical trials.

Conclusion

The customized design of AVF needles, especially the innovative approach aimed at optimizing hemodynamic performance, represents the evolution of this field from "meeting functional requirements" to "seeking excellence". By applying advanced technologies such as 5-axis laser cutting, manufacturers can collaborate with clinical experts to develop the next generation of AVF needles with features like multiple side holes and spiral grooves. These designs aim to address the clinical limitations of traditional single-hole needles. By stabilizing blood flow, reducing shear forces, and improving the flow field, they ultimately achieve the comprehensive goals of enhancing dialysis efficacy, ensuring patient safety, and optimizing the treatment experience. This customized development driven by clinical needs and driven by technological innovation is a vivid manifestation of the continuous progress of the medical device industry and its better service to patients.