Slow, continuous therapies for renal failure are used in critically ill patients and may involve hemodialysis or hemofiltration. Anticoagulation during the procedure needs to be carefully modulated to prevent both excessive bleeding and blood clotting in the therapeutic system.
Protocol for arteriovenous hemodialysis:
(1) Heparin in priming and rinsing solutions.
(2) Give a bolus of 2000 IU of heparin into the arterial line at the start of therapy.
(3) Begin a heparin infusion of 500 IU per hour.
Monitoring goals:
(1) maintain arterial PTT 40-45 seconds
(2) maintain venous PTT > 65 seconds
Adjusting anticoagulation:
(1) If the arterial PTT is < 40 seconds, then increase heparin infusion by 100 IU per hour.
(2) If the arterial PTT is > 45 seconds, then decrease the heparin infusion by 100 IU per hour.
(3) If the arterial PTT is 40-45 seconds, and if the venous PTT is < 60 seconds, then increase the heparin infusion by 100 IU per hour.
Limitations:
• Inadequate anticoagulation results in abnormal clotting, especially in the extracorporeal circuit, which can interfere with the effectiveness or terminate the procedure.
• Excessive anticoagulation can result in patient hemorrhage.
