Regional blood flow during hyperoxic haemodilution.
BACKGROUND
Ventilation with pure oxygen (hyperoxic ventilation, HV) increases arterial oxygen content (CaO(2)). However HV induces arteriolar constriction and thus potentially affects O(2) supply. We therefore investigated the effects of HV on regional blood flow (RBF) and O(2) supply of different vital organs during moderate normovolaemic anaemia.


METHODS
Twenty-two anaesthetized dogs were haemodiluted under normoxia (i.e. FiO(2) = 0.21) to a target haemoglobin concentration (Hb) of 7 g dl(-1) and were subsequently ventilated with pure O(2). RBF was determined by use of the radioactive microspheres method in the myocardium, kidney, skeletal muscle, liver, intestine, stomach, and pancreas at Hb = 7 g dl(-1) and after subsequent initiation of HV. RBF in proportion to cardiac output (RBF(relative)), the variation coefficient of RBF (VC) and regional O(2) supply (rDO(2)) were calculated.


RESULTS
Initiation of HV at Hb = 7.0 +/- 0.3 g dl(-1) reduced cardiac index (-17%) as well as RBF within the myocardium (-21%), pancreas (-25%), and skeletal muscle (-25%), whereas renal, hepatic, and intestinal RBF remained unchanged. Consequently RBF(relative) of the latter organs increased. Heterogeneity of RBF was marginally affected by HV.


CONCLUSIONS
The initiation of HV during moderate normovolaemic anaemia (Hb =7 g dl(-1)) was accompanied by RBF redistribution with preference for renal, hepatic and intestinal O(2) supply. Cardiac, pancreatic and muscular O(2) supply decreased, however without any critical restriction of organ function.
Meier
Jens
J
Department of Anesthesiology, Johann Wolfgang Goethe-University, Frankfurt, Germany. meier@em.uni-frankfurt.de
Pape
Andreas
A
Kleen
Martin
M
Hutter
Jörg
J
Kemming
Gregor
G
Habler
Oliver
O
D000818:Animals; D016063:Blood Loss, Surgical; D001810:Blood Volume; D004285:Dogs; D006438:Hemodilution / Q000379:methods*; D006439:Hemodynamics; D008863:Microspheres; D010100:Oxygen / Q000008:administration & dosage / Q000378:metabolism*; D012039:Regional Blood Flow / Q000502:physiology*; D018709:Statistics, Nonparametric
D010100:Oxygen