The Site of Injection Affects Erythropoietin Levels During Dialysis

Abstract

Serum concentrations of rHuEPO were measured after injection into different sites within the blood lines in patients undergoing hemodialysis. The authors compared the venous port to venous drip chamber injection using two separate delivery systems and their associated blood lines (Cobe Centry 3 [CGH, Lakewood, CO] and Fresenius A2008 [Fresenius USA, Concord, CA]). The former has a unique cartridge drip chamber and the latter a more conventional set-up. Patients were injected at both sites with their usual dose of rHuEPO at the beginning of dialysis and plasma levels were measured throughout dialysis. Significantly lower plasma levels occurred only after injection into the venous drip chamber using the Fresenius delivery system. Simultaneous samples were drawn from the venous and arterial ports and upper and lower drip chamber in a group of patients dialyzing on this system. Levels were 26 and 32 times higher in the upper and lower drip chamber compared to the venous sample, which exceeded the arterial sample. No significant rebound of rHuEPO was detected at the end of dialysis after saline rinse back in patients in whom the rHuEPO was injected into the drip chamber. The authors conclude that injection of erythropoietin into the venous drip chamber of the Fresenius delivery system should be avoided because substantial quantities are lost by "trapping," and not eluted at the end of dialysis.