Caring for fistula health in hemodialysis​

Conventional single‑needle therapy performs hemodialysis through a single vascular access by alternating between blood withdrawal and blood return in separate phases. This results in an intermittent blood flow through the dialyzer, which may limit treatment efficiency.

Conventional single‑needle therapies are associated with several technical and clinical limitations:

• Blood flow: Difficult to achieve and maintain very high blood flow rates.
• Recirculation: Higher compared to double‑needle therapy³, mainly due to low blood flow, dead space in the Y‑connector, and compliance of the bloodlines.⁴
• Kt/V and clearance: Ensuring an adequate dialysis dose has traditionally been considered a challenge and was long regarded as the Achilles’ heel of single‑needle techniques.⁴
• Handling: Single‑needle systems are often perceived as more difficult to manage due to frequent pressure‑related alarms.

Single‑needle cross‑over therapy (SNCO) builds on the single‑needle principle but uses pressure‑controlled, cross‑regulated switching in combination with expansion chambers. This technology enables a more stable, quasi‑continuous blood flow through the dialyzer, resulting in reduced recirculation, smoother pressure conditions, and improved dialysis efficiency.

The Single‑Needle Cross-Over procedure enables a continuous blood flow through the dialyzer. During Single‑Needle crossover treatment, pressure and pulsation conditions within the dialyzer are comparable to those in double‑needle dialysis. The blood pumps transport blood at a constant rate from the arterial expansion chamber through the dialyzer to the venous expansion chamber. Pressure within the venous chamber is monitored via the venous pressure sensor, while pressure in the arterial chamber is monitored via the arterial pressure sensor.

Dialog iQ offers an auto mode for Single‑Needle dialysis. In this mode, only the phase volume needs to be set; blood flow is then regulated automatically. The advantages of this system include reduced standstill periods, an increased total treated blood volume, and—from the user’s perspective—automatic adjustment of the optimal blood flow without the need for manual interaction at the machine.⁴

Diacan Flex is a single-use flexible peripheral vascular access safety catheter for extracorporeal blood purification therapies. It is intended to provide access to arteriovenous fistulas, arteriovenous grafts and veins.

The catheter is inserted into the patient’s peripheral vascular system via an introducer needle. The needle is then removed while the soft, flexible plastic capillary remains in the vessel. The product is equipped with an incorporated safety shield which automatically covers the needle tip and an inbuilt blood control valve to prevent blood exposure after needle removal.

The plastic capillary with soft material and side holes is designed to increase patient comfort and to reduce the risk of vessel injury with appropriate flow rates.

The insertion of fistula needles for every hemodialysis (HD) treatment is attended by needle injury to the fistula and may cause deleterious effects. Measures to restore fistula patency are required that add significant therapeutic burden to this patient population, as well as cost burden to the health-care system.

The introduction of flexible plastic catheters, like Diacan Flex for dialysis treatments instead of steel needles can be seen as a milestone for the protection of fistula health and patency. Fistula trauma during insertion and fistula infiltrations during dialysis treatments due to involuntary movements of the patient could be markedly and resulted in less fistula interventions.⁵ Patients cannulated with plastic catheters, like Diacan Flex had 40% fewer fistula complications than those cannulated using metal needles. Even in the absence of complications, dialysis adequacy (Kt/V) is improved when flexible plastic catheters are used.⁸