ABSTRACT
A classification o f acute b lood loss is show n in Table 14.1. First, there is the im m ediate o r u rgen t need for red b lood cells and, in som e instances, o th er b lood products. Patients presenting w ith acute hem orrhage w ith loss o f less th an 40% o f the ir b lood volum e m ay tolerate fluid replacem ent w ith crystalloids, assum ing a n o rm al hem oglobin level before the acute event. A problem , however, m ay be estim ating the loss o f intravascular volum e and the po ten tial for fu rther red b lood cell loss. Ordinarily, for Class 1 and Class 2 acute trau m a patients (Table 14.1), red cell transfusions are n o t needed, particu larly in young patients w ho can adap t well to the acute b lood loss anem ia, assum ing th a t contro l o f hem orrhage has been, o r is likely to be, achieved. If in excess o f 40% blood volum e loss has oc cu rred in young patients, o r less in elderly people w ho m ay have pre-existing com prom ised critical organ function , the u rgen t need for red b lood cell transfusions m ay exist. Two difficulties arise in this setting. ( 1 ) The circum stances m ay n o t allow the collection o f a sam ple for routine com patibility testing (C hapter 7). Trans fusion o f b lood g roup O red cells to these individuals is an appropria te early m ea sure. Rhesus negative units should be used, if possible, and in all situations for females o f child bearing age, arb itra rily u n d er the age o f 50 years. (2) If m ore tim e allows, a b lood sam ple can be collected. U nfortunately the no rm al identification m echanism s for insuring sam ple in tegrity m ay n o t be followed appropriately b e cause o f pressures in dealing w ith p a tien t resuscitation. An inappropria tely la beled specim en o r a m isidentified specim en is then received in the b lood bank, resulting in frustra tion on the p a rt o f the em ergency room and b lood ban k p e r sonnel. For inappropria tely labeled specim ens, the con tinued release o f group O blood rem ains necessary. M islabeled specim ens are particu larly dangerous in this setting as the stage is set for an acute hem olytic reaction (C hapter 32). It is essen tial to collect and label the specim en correctly at the p o in t o f sam ple collection an d th e ph lebotom ist m u st sign (and date) the specim en. A specim en collected in to an unlabeled tube, w hich is rem oved from the p o in t o f collection and labeled elsewhere, is dangerous. In sum m ary, if tim e precludes adherence to correct label ing protocol, it is better to con tinue to transfuse g roup O (uncrossm atched) blood.
