<unk>  refers to a rapid, direct method of introducing or removing devices or chemicals from the bloodstream. In hemodialysis,<unk>  is used to remove the patient's blood so that it can be filtered through the dialyzer. Three primary methods are used to gain<unk>  to the blood: an intravenous catheter, an arteriovenous fistula (AV) or a synthetic graft. In the latter two, needles are used to puncture the graft or fistula each time dialysis is performed. The type of<unk>  created for patients on hemodialysis is influenced by factors such as the expected time course of a patient's kidney failure and the condition of his or her<unk> sculature. Patients may have multiple<unk> es, usually because an AV fistula or graft is maturing and a catheter is still being used. The creation of all these three major types of<unk> es requires surgery.
Vascular access
Venous access
Blood transfusion
Blood donation
Electrocoagulation
Preoperative care
Dental anesthesia
Blood product