Splanchnic oxygen consumption is impaired during severe acute normovolemic anemia in anesthetized humans.
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.
Mathru
Mali
M
Department of Anesthesiology, Comprehensive Cancer Center, University of Alabama at Birmingham, 35249, USA.
Solanki
Daneshvari R
DR
Woodson
Lee C
LC
Funston
J Sean
JS
Ozkan
Orthan
O
Henkel
Sheryl N
SN
Wang
Deli
D
Gore
Dennis
D
Prough
Donald S
DS
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*
D006454:Hemoglobins