To evaluate the use of the activated partial thromboplastin time (APTT), as measured by the Coag‐A‐Mate semi‐automatic unit, in lowering the dosage of heparin in stable chronic hemodialysis patients, four protocols for anticoagulation were utilized. Ten patients were dialyzed five times with each protocol. In protocol I, clotting time was performed baseline, 2 and 4 hours and in protocol II, baseline and every 30 minutes, with heparin administered by bolus to keep the clotting time at 2–2% times normal. In protocols III and IV the APTT was performed every 30 minutes, with heparin given by bolus in protocol III and infusion in protocol IV, to keep the APTT 11/2‐‐2 times normal. Protocol I required 6000±543 U of heparin with the dose decreasing significantly to 3694 ± 158 U in protocol II, 2634 ± 139 U in protocol III and 2013±117 U in protocol IV (P<0.05 ‐<0.001). Three episodes of clotting occurred, one in protocol III and two in protocol IV. There was no bleeding, and clearances of urea, creatinine, phosphate and uric acid at 1 and 5 hours were similar in all protocols. APTT, as measured by the Coag‐A‐Mate unit, provides a simple means of lowering heparin requirements in routine dialysis patients. © 1979 International Center for Artificial Organs and Transplantation
