Petersen J, Kang MS, Yeh I
The site of injection affects erythropoietin levels during
dialysis
ASAIO J
(Jul) 42:263-265 1996

EPO, when given intravenously, is usually given as a bolus into the
venous line at the end of dialysis. The venous injection can be via a
sampling port which is between the dialyzer and drip chamber (Cobe
Centry 3) or between the venous drip chamber and patient (Fresenius
lines). An alternative site of injection is into the venous drip
chamber itself. The authors compared blood EPO levels after
injecting their patients with EPO one week via the sampling port, and
one week via the drip chamber. Both Cobe and Fresenius lines were
used.
When the EPO was given via the Cobe lines, it made no
difference if it was injected into the sampling port or into the drip
chamber itself. Both methods resulted in a prompt increase in plasma
EPO levels. However, with the Fresenius lines, a good plasma EPO
increase was seen after injection into the sampling port, but only a
minimal increase was seen when EPO was injected directly into the drip
chamber. The authors suggest that the lack of rise in plasma EPO
after injection into the drip chamber directly is due to trapping of
the injected EPO at the top of the blood/air interface, which
apparently occurs to a lesser extent with the cartridge type of drip
chamber found with the Cobe lines. They suggest that injection of EPO
into the drip chamber via Fresenius lines might be a covert cause for
EPO "resistance".
Comment: With the high costs of EPO, this article has
an extremely high clinical and cost relevance. (John T.
Daugirdas, M.D., University of Illinois at Chicago)