There are several drawbacks to allogenic blood transfusions:

Incompatibility and allergic reactions: Traumatic hemorrhagic shock is a very time sensitive situation not allowing for a cross-match or even identification of type specific blood.  Only 6% of the population has the O blood type (also known as the “universal donor”) making it a precious commodity.  Even with mandatory cross-matching, ABO-incompatible hemolytic transfusion is the most common cause of acute fatalities from blood transfusion (due to clerical errors).

Disease transmission: There is rigorous screening for infectious diseases but blood cannot be efficiently screened for a blood-borne pathogen until a disease and its serologic markers are identified (usually after many people have become infected).

Blood storage limitations: The current maximum storage time for whole blood is 42 days.  The blood must be refrigerated.

Limited availability: There is an estimated shortage of almost 200 million units of blood worldwide each year.

There are many ways that we can avoid allogenic transfusions.  Some include drug therapy (erythropoetin, interleukin 11), autologous transfusion, and cell salvage.  Another option is artificial oxygen carriers. There are two main categories of oxygen carriers: perfluorocarbon (PFCs) and hemoglobin-based oxygen carries (HBOCs).  HBOCs can be further categorized by the hemoglobin source (bovine, expired human blood, and recombinant) or by modification techniques.