▁hom olog ous ▁blood ▁trans f usion ▁is ▁necessary ▁to ▁maintain ▁H m , ▁even ▁if ▁AN H ▁is ▁used . ▁This ▁model ▁can ▁be ▁used ▁to ▁identify ▁when ▁AN H ▁may ▁be ▁used ▁for ▁a ▁given ▁patient ▁and ▁the ▁degree ▁of ▁AN H ▁necessary ▁to ▁maxim ize ▁that ▁benefit . ▁ ▁For ▁example , ▁if ▁Hi ▁is ▁ 0 . 3 0 ▁or ▁less ▁it ▁is ▁not ▁possible ▁to ▁save ▁a ▁red ▁cell ▁mass ▁equivalent ▁to ▁two ▁units ▁of ▁hom olog ous ▁PR BC ▁even ▁if ▁the ▁patient ▁is ▁hem od il uted ▁to ▁an ▁H m ▁of ▁ 0 . 1 5 . ▁That ▁is ▁because ▁from ▁the ▁R CM ▁equation ▁the ▁patient ▁R CM ▁falls ▁short ▁from ▁the ▁equation ▁giving ▁above . ▁If ▁Hi ▁is ▁ 0 . 4 0 ▁one ▁must ▁remove ▁at ▁least ▁ 7 . 5 ▁units ▁of ▁blood ▁during ▁AN H , ▁resulting ▁in ▁an ▁H m ▁of ▁ 0 . 2 0 ▁to ▁save ▁two ▁units ▁equivalence . ▁Clear ly , ▁the ▁greater ▁the ▁Hi ▁and ▁the ▁greater ▁the ▁number ▁of ▁units ▁removed ▁during ▁hem od il ution , ▁the ▁more ▁effective ▁AN H ▁is ▁for ▁prevent ing ▁hom olog ous ▁blood ▁trans f usion . ▁The ▁model ▁here ▁is ▁designed ▁to ▁allow ▁do ctors ▁to ▁determine ▁where ▁AN H ▁may ▁be ▁benef icial ▁for ▁a ▁patient ▁based ▁on ▁their ▁knowledge ▁of ▁the ▁Hi , ▁the ▁potential ▁for ▁S BL , ▁and ▁an ▁estimate ▁of ▁the ▁H m . ▁Though ▁the ▁model ▁used ▁a ▁