title: Splanchnic oxygen consumption is impaired during severe acute normovolemic anemia in anesthetized humans.
abstract: BACKGROUND
  In conscious humans, reduction in hemoglobin concentration to 5 g/dl did not produce inadequate systemic oxygenation. However, systemic measures of inadequate oxygenation may not be sufficiently sensitive to detect inadequate oxygenation in individual organs such as splanchnic organs. The authors tested the hypothesis that acute normovolemic anemia to hemoglobin less than 6.0 g/dl in anesthetized humans reduces splanchnic oxygen consumption because of diminished whole body oxygen delivery.
  
  
  METHODS
  Elective spine (n = 12) and abdominal (n = 7) surgery patients underwent acute normovolemic anemia to decrease the hemoglobin concentration close to 6.0 g/dl. The authors assessed the development of supply-dependent conditions in systemic and regional vascular beds by two primary measures before and after acute normovolemic anemia: oxygen consumption and surrogate biochemical markers of anaerobic metabolism, including plasma lactate, regional lactate kinetics, and ketone body ratio.
  
  
  RESULTS
  When hemoglobin was reduced from 13.6 +/- 1.2 to 5.9 +/- 0.3 g/dl, oxygen supply dependency occurred in the splanchnic and preportal tissues but not at the systemic level. Regional supply dependency was accompanied by biochemical markers of anaerobic metabolism.
  
  
  CONCLUSIONS
  In anesthetized humans, a reduction in hemoglobin to 5.9 g/dl by acute normovolemic anemia diminished splanchnic and preportal whole body oxygen delivery and impaired splanchnic and preportal oxygen consumption. This was accompanied by increased plasma levels of regional lactate and an increased beta-hydroxybutyrate-to-acetoacetate ratio. These findings suggest that the risk to the gastrointestinal tract during acute normovolemic anemia may be underestimated.
authors.affiliation: Department of Anesthesiology, Comprehensive Cancer Center, University of Alabama at Birmingham, 35249, USA.
authors.forename: Mali
authors.initials: M
authors.lastname: Mathru
authors.forename: Daneshvari R
authors.initials: DR
authors.lastname: Solanki
authors.forename: Lee C
authors.initials: LC
authors.lastname: Woodson
authors.forename: J Sean
authors.initials: JS
authors.lastname: Funston
authors.forename: Orthan
authors.initials: O
authors.lastname: Ozkan
authors.forename: Sheryl N
authors.initials: SN
authors.lastname: Henkel
authors.forename: Deli
authors.initials: D
authors.lastname: Wang
authors.forename: Dennis
authors.initials: D
authors.lastname: Gore
authors.forename: Donald S
authors.initials: DS
authors.lastname: Prough
mesh_terms: D000328:Adult; D000740:Anemia / Q000097:blood* / Q000139:chemically induced; D000768:Anesthesia, General / Q000379:methods*; D005260:Female; D006438:Hemodilution / Q000009:adverse effects* / Q000379:methods; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D013152:Splanchnic Circulation / Q000502:physiology*
chemical_list: D006454:Hemoglobins