title: The acidosis-induced right shift of the HbO₂ dissociation curve is maintained during erythrocyte storage.
abstract: OBJECTIVE
  In fresh blood, tissue hypoxia increases microcirculatory acidosis, which enhances erythrocyte O(2) unloading and increases the amount of available O(2). Storage of erythrocytes increases the HbO(2) affinity and reduces O(2) unloading. We examined the development of the affinity change during a period of 5 weeks of storage by present blood bank standards, and investigated to what extent acidosis offsets the affinity change.
  
  
  METHODS
  Blood from volunteer donors was processed and stored as erythrocyte concentrates (EC). At 2-5 day intervals, EC were drawn from the bags and suspended in plasma and crystalloids to an Hb ≈ 10 g/dL. The suspensions were adjusted to give a pH of 7.40, 7.10, 6.80 or 6.30 and equilibrated with different gas mixtures to SO(2) 0, 25, 50, 75 and 100%. Measurements of the PO(2)/SO(2) pairs at each pH were used to calculate the position of the HbO(2) curve and its P(50) value.
  
  
  RESULTS
  A significant leftward shift in the HbO(2) curve was established after 1 week of storage; after 2.5 weeks only minor further changes were observed. Acidification right-shifted the HbO(2) curve, after 2.5 weeks of storage the curve at pH 7.10 was similar to that for fresh blood at pH 7.40. Calculations of extractable O(2) showed that the left-shifted HbO(2) curve of stored EC could be advantageous at a low arterial PO(2).
  
  
  CONCLUSIONS
  The rightward shift of the HbO(2) curve due to acidosis is well maintained in stored erythrocytes, a moderate pH decrease offsets the storage-induced increased HbO(2) affinity.
authors.affiliation: Department of Acute Medicine and the Norwegian National Center for NBC Medicine, Oslo University Hospital, Ullevål, Oslo, Norway. helge.opdahl@ulleval.no
authors.forename: Helge
authors.initials: H
authors.lastname: Opdahl
authors.forename: Tævje A
authors.initials: TA
authors.lastname: Strømme
authors.forename: Lise
authors.initials: L
authors.lastname: Jørgensen
authors.forename: Livia
authors.initials: L
authors.lastname: Bajelan
authors.forename: Hans E
authors.initials: HE
authors.lastname: Heier
mesh_terms: D000138:Acidosis; D001793:Blood Preservation; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000097:blood; D010108:Oxyhemoglobins / Q000378:metabolism*; D013997:Time Factors
chemical_list: D010108:Oxyhemoglobins; D010100:Oxygen