Material relevant to background questions was gathered by fellows or registrars under the supervision of CRG members. Sources included medical textbooks, grey literature, published scientific and review articles, series yearbooks and other relevant medical literature; however, systematic review processes were not applied. The questions researched are listed in Box 2.2.
Box 2.2 Background research questions
- Background question 1 – What is critical bleeding?
- Background question 2 – What is the definition of massive transfusion? What is an agreed (suitable) definition of massive transfusion?
- Background question 3 – In the management of critical bleeding, are (a) permissive hypotension, also called minimal volume hypotensive resuscitation, and (b) damage control surgery associated with improved patient outcomes?
- Background question 4 – Does the use of fresh (stored unrefrigerated for < 48 hours) or ultra-fresh (stored for < 4 hours) whole blood influence patients’ morbidity and mortality?
- Background question 5 – What effect does the age of red blood cells used in transfusions have on patients’ morbidity and mortality?