The document discusses alternatives to red blood cell transfusion called oxygen carriers (OCs), including hemoglobin-based oxygen carriers (HBOCs) derived from mammalian sources and modified chemically or recombinantly, and perfluorocarbons (PFCs) which are inert compounds that can absorb oxygen. An ideal OC would have characteristics like rapid availability, effective oxygen carrying capacity, universal compatibility and long shelf life. Potential uses include treatment of hemorrhagic shock, ischemia, and as perfusional protection during surgery. However, HBOCs may cause vasoactivity and interference with assays, while PFCs can cause flu-like symptoms and lower platelet counts.