Discussion of albumin in Biotime patents.
I noticed that Biotime patent 5,747,071 "Plasma-like substance" ( patents.ibm.com ) describes the use of albumin in the invention. The invention covers a mixture of one or two oncontic agents (from hi or low weight HES, Dextran, Albumin), electrolytes, buffer, and sugar:
"It is particularly advantageous to use albumin in the solutions according to the invention. As a mammalian blood protein, albumin has several important physiological functions which are more completely preserved when the solution according to the invention comprise albumin. As a blood protein, ablumin is an important ion-binding protein which binds to essential divalent cations, particularly calcium ion. Thus, by using albumin as an oncotic agent in the solutions according to the invention, particularly the two oncotic agent solutions, the capacity of the subject to maintain normal circulating and tissue calcium ion concentrations is enhanced over solutions such as HetaStarch, Pentastarch, Rheomax and other similar commercial preparations. Approximately 50% of the Calcium ion in the mammalian circulation is bound to protein and albumin comprise approximately 60% of the circulating blood proteins."
These seem to be some reasons why albumin continues to be widely used. It also shows that the inventors did not assume that the adding Ca++ to hetastarch was going to solve all the coagulation problems.
I had previously posted an excerpt on hypocalcemia from a website on massive blood volume replacement ( trauma.org ):
Hypocalcaemia
Each unit of blood contains approximately 3g citrate, which binds ionized calcium. The healthy adult liver will metabolise 3g citrate every 5 minutes. Transfusion at rates higher than one unit every five minutes or impaired liver function may thus lead to citrate toxicity and hypocalcaemia. Hypocalcaemia does not have a clinically apparent effect on coagulation, but patients may exhibit transient tetany and hypotension. Calcium should only be given if there is biochemical, clinical or electrocardiographic evidence of hypocalcaemia.
Steve
btim.dyn.ml.org |
