Effects of Acute Normovolemic Hemodilution on Intrapulmonary Shunt and Systemic Oxygen Delivery Balance during One Lung Ventilation in Dogs / 대한마취과학회지

ABSTRACT

BACKGROUND: The present study was done to elucidate the effects of acute normovolemic hemodilution (ANH) on intrapulmonary shunt (Qs/Qt) and systemic oxygen delivery balance during one lung ventilation (OLV). METHODS: To induce one lung ventilation, an atelectasis of the right lung was produced in anesthetized mongrel dogs. In 6 dogs with OLV, ANH was produced by sequential hemodilution with hydroxyethyl starch. ANH was divided into 3 stages (ANH0 no hemodilition, ANH1 first hemodilution, ANH2 second hemodilution). Qs/Qt was measured by using blood gas analysis. Various hemodynamic parameters, oxygen delivery, and consumption were measured or calculated indirectly. RESULTS: After hemodilution, hemoglobin levels at each stage were 9.9 +/- 1.3 g/dl (ANH0), 7.0 +/- 1.0 g/dl (ANH1), and 5.2 +/- 0.7 g/dl (ANH2). The Qs/Qt of ANH2 stage increased from 25.0 11.4% of ANH0 to 35.4 9.2% (P 0.05). Global oxygen delivery was markedly decreased by hemodilution in OLV (P < 0.05), whereas global oxygen consumption was maintained. CONCLUSIONS: We conclude that global oxygen delivery balance is preserved by ANH in this study. However, extreme ANH has a deleterious effect on pulmonary gas exchange, possibly through the attenuation of hypoxic pulmonary vasoconstriction during one-lung ventilation. On the basis of this study, increased cardiac output generated by ANH might be the cause of inhibition or blunting of hypoxic pulmonary vasoconstriction.