To: Prospector who wrote (2499 ) 7/3/1998 10:09:00 PM From: chirodoc Read Replies (2) | Respond to of 5402
USE OF OXYGENT, A PERFLUOROCHEMICAL-BASED OXYGEN CARRIER, AS AN ALTERNATIVE TO INTRAOPERATIVE BLOOD TRANSFUSION. ......this gives some idea of why we beat this dead horse. .....these 2 paragraphs explains HOW PFC'S work. i don't think this has been explained well. the rest of the article is a bit dense, but might be food reading for doubters. ---------------------- Oxygen molecules are dissolved in PFC particles as they pass, in the blood, through the lungs. These oxygen-loaded PFC particles travel through the blood to the capillaries where tissue oxygen concentrations are low. At that point, oxygen is exchanged for carbon dioxide molecules. PFCs exchange gases more rapidly and more completely than do red cells because they load and unload gases by simple diffusion. When the particles return to the lungs, the carbon dioxide is expired and the PFC particles take on new oxygen molecules. Oxygen delivery to tissues by PFC emulsions differs fundamentally from that of Hb in red cells. Hb has a fixed capacity to bind 4 molecules of oxygen per tetramer; therefore, oxygen transport is directly related to the Hb concentration and requires dissociation of the oxygen from the heme prior to transfer to tissues. By contrast, oxygen physically dissolves in PFCs, which results in a more rapid loading and unloading versus Hb.22 More importantly, the oxygen-carrying capacity of a PFC emulsion is directly proportional to the partial pressure of oxygen (i.e., according to Henry's Law) and can be maximized simply by elevating the inspired oxygen. --------------------- Peter E. Keipert, Ph.D. Alliance Pharmaceutical Corp., 3040 Science Park Road, San Diego, CA, 92121