RESUMO
BACKGROUND: It is known that hypoxic pulmonary vasoconstriction increases as a result of intermittent regional hypoxic challenges. The aim of this study was to compare the effects of sevoflurane and propofol on oxygenation and shunt fraction during one-lung ventilation in a novel model of hypoxic preconditioning before one-lung ventilation. METHODS: Sixteen Wistar-albino rats were anesthetized intra-peritoneally before venous and arterial cannulations and tracheotomized. The animals were randomly allocated to receive either sevoflurane 2% or 10mg/kg/h propofol infusion and ventilated with 100% oxygen at an inspiratory rate of 80 breaths/min for 30min. Three cycles of one-lung ventilation and two-lung ventilation were performed and one-lung ventilation was continued for 15min. Arterial blood gas samples were obtained as follows: after cannulation and tracheotomy, following 30min of treatment with sevoflurane or propofol, and at the 5th and 15th min of one-lung ventilation. RESULTS: The PaO2 levels were higher and shunt fractions were lower in rats receiving propofol compared to rats treated with sevoflurane but the difference was not significant; the two groups were comparable in terms of PaCO2. CONCLUSIONS: The similar effects of sevoflurane and propofol on PaO2 during one-lung ventilation following hypoxic preconditioning may be due to other causes beside the inhibition of hypoxic pulmonary vasoconstriction. Gradual transition to one-lung ventilation is a novel technique for preconditioning experiments for one-lung ventilation.