Complex sentence: The service was formed in 1946 as the Blood Transfusion Service (still often referred to as this) the name change came about in 1991 to reflect the move away from a regionally based service to a nationally organised one.
Split into simpler sentences: The service was formed in 1946 as the Blood Transfusion Service and is still often referred to as this. The name change came about in 1991 to reflect the move away from a regionally based service to a nationally organised one.