2 Weight-Based Heparin Protocols

While there is a paucity of clinical literature describing specific anticoagulation protocols used in hemodialysis, it is generally accepted that maintaining the integrity of the extracorporeal circuit during treatment is necessary for delivering dialysis. Clinical practice guidelines for chronic hemodialysis from Europe, the United Kingdom, the United States, Canada and Australia all recommend heparin anticoagulation for the majority of hemodialysis patients.

Heparin-free dialysis is usually reserved for patients with heparin-induced thrombocytopenia, heparin allergy or a high risk for bleeding. This practice is technically demanding; may lead to gross loss of the extracorporeal circuit; and negatively impacts hemodialysis adequacy, filter life, extracorporeal blood loss, nursing time and overall costs. Using citrate-based dialysate can reduce, but does not eliminate, the need for heparin anticoagulation.

For effective treatment in most chronic in-center hemodialysis patients, heparin anticoagulation should be included in the dialysis prescription. Oral anticoagulation alone, use of specific dialysates, dialyzers and/or blood lines, regional citrate or saline flushes have not been conclusively demonstrated to be an effective or practical means of anticoagulation in the in-center hemodialysis environment. In an effort to develop a standard protocol, DaVita carried out a pilot to assess two weight-based heparin protocols (standard-dose and low-dose), which are listed below. Outcomes were compared to those among patients receiving heparin-free dialysis. The protocols were designed to have a higher and lower dose to try to establish the most effective dosing signals and enhance physician choice and patient safety.

1. Standard-dose protocol

Start with a loading dose of 25 U/kg of heparin, followed by 600 units of heparin each hour. The total delivered dose is approximately 2,500 to 5,000 units, based on weight and treatment duration assumptions. For patients with an arteriovenous fistula or graft, stop the heparin 60 minutes before the end of the treatment. For patients with a central venous catheter, stop the heparin at the end of the treatment.

The clinical rationale for this protocol is provided by the findings of Cronin and Reilly at the University of Texas Southwestern and VA North Texas Healthcare Systems and Shen and Winkelmayer at Stanford University. This protocol is consistent with current European guidelines: The British Renal Association suggests administration of an unspecified loading dose of heparin followed by a continuous dose of 500 to 1,500 U/hr. The European Renal Association and European Dialysis and Transplant Association specifies a loading dose of 50 U/kg followed by 800-1500 U/hr. The National Kidney Foundation, the Canadian Society of Nephrology and the Australian CARI guidelines do not contain specific protocols or heparin dosages. However, they all state that anticoagulation should be prescribed during hemodialysis unless contraindicated.

2. Low-dose protocol

This protocol is for patients with a high risk of bleeding. Start with a loading dose of 10 U/kg of heparin, followed by 400 units of heparin each hour. The total delivered dose is approximately 1,800 to 2,800 units, based on weight and treatment duration assumptions. For patients with an arteriovenous fistula or graft, stop the heparin 60 minutes before the end of the treatment. For patients with a central venous catheter, stop the heparin at end of the treatment.

The clinical rationale for this protocol is based upon published experience with patients who are at higher risk of bleeding based on the work of Shen and Winkelmayer at Stanford University.

It should be noted that the low-dose heparin protocol should be used for select patients when there is concern about using higher doses of anticoagulants or a physician deems necessary. Examples of such situations include:

• Recent bleed or risk of bleeding (e.g., cerebral or gastrointestinal)
• Recent hospital discharge with a diagnosis dictating careful use of anticoagulation therapies (e.g., post-surgery)
• Use of oral anticoagulants
• Persistent bleeding from vascular access after dialysis
• Thrombocytopenia
• Familial or inherited bleeding disorders
• Recent fall or bruising
• Severe osteoporosis

Additionally, as evidenced in DaVita’s pilot, it appears that the low-dose protocol is equally successful at achieving equivalent clinical outcomes as the standard-dose protocol.

Note: The risks of anticoagulation in dialysis patients should not be understated or ignored. Indeed, effective chronic anticoagulation requires a balance between preventing extracorporeal circuit clotting and avoiding adverse events, such as excessive bleeding from the vascular access site, intracranial hemorrhage, interactions with oral anticoagulants, heparin-induced thrombocytopenia, osteoporosis and aldosterone inhibition.