A central venous catheter tube installed the neck. Permits large amounts of blood/fluid to be transferred. Used initially for dialysis until an arm or hand access can be surgically installed for Permanent dialysis.
As someone who spent three years on dialysis and then came off AND WITHOUT a transplant, I've had four different types of access.
-CVS -- Both neck and chest. CVS for chest was best for me while on hemodialysis.
-AV Fistula -- Not so good. Frequent interruptions during dialysis for blood flow issues.
-PD Catheter -- Good results and even better it is self treatment not requiring frequent visits to the dialysis clinic. While home treatment can also use hemodialysis, it is much more complicated and requires a willing helper.
The absolute best -- no dialysis from kidney function improvement that can work for some.