ution ▁must ▁begin ▁when ▁S BL ▁begins . ▁The ▁R CM ▁available ▁for ▁re trans f usion ▁after ▁AN H ▁( RC M m ) ▁can ▁be ▁calculated ▁from ▁the ▁patient ' s ▁Hi ▁and ▁the ▁final ▁h emat oc rit ▁after ▁hem od il ution ( H m ) ▁ ▁The ▁maximum ▁S BL ▁that ▁is ▁possible ▁when ▁AN H ▁is ▁used ▁without ▁falling ▁below ▁H m ( BL H ) ▁is ▁found ▁by ▁assuming ▁that ▁all ▁the ▁blood ▁removed ▁during ▁AN H ▁is ▁returned ▁to ▁the ▁patient ▁at ▁a ▁rate ▁sufficient ▁to ▁maintain ▁the ▁h emat oc rit ▁at ▁the ▁minimum ▁safe ▁level ▁ ▁If ▁AN H ▁is ▁used ▁as ▁long ▁as ▁S BL ▁does ▁not ▁exceed ▁B L H ▁there ▁will ▁not ▁be ▁any ▁need ▁for ▁blood ▁trans f usion . ▁We ▁can ▁conclude ▁from ▁the ▁for ego ing ▁that ▁H ▁should ▁therefore ▁not ▁exceed ▁s . ▁The ▁difference ▁between ▁the ▁B L H ▁and ▁the ▁B L s ▁therefore ▁is ▁the ▁increment al ▁surg ical ▁blood ▁loss ▁( BL i ) ▁possible ▁when ▁using ▁AN H . ▁ ▁When ▁expressed ▁in ▁terms ▁of ▁the ▁R CM ▁▁ ▁Where ▁R CM i ▁is ▁the ▁red ▁cell ▁mass ▁that ▁would ▁have ▁to ▁be ▁admin ister ed ▁using ▁hom olog ous ▁blood ▁to ▁maintain ▁the ▁H m ▁if ▁AN H ▁is ▁not ▁used ▁and ▁blood ▁loss ▁equals ▁B L H . ▁ ▁The ▁model ▁used ▁assumes ▁AN H ▁used ▁for ▁a ▁ 7 0   kg ▁patient ▁with ▁an ▁estimated ▁blood ▁volume