Sevoflurane has no inhibitory effect on hypoxic pulmonary vasoconstriction (HPV) in dogs

There is no general agreement on the effect of inhalation anesthetics on hypoxic pulmonary vasoconstriction (HPV). We have examined the effect of sevoflurane upon the pulmonary vascular response to a left lower lobe (LLL) hypoxia in dogs by continuously measuring the fractional distribution to the LLL of total pulmonary blood flow (Q(LLL)/Q(T)) employing an ultrasonic transit time rheometer with flow probes attached to the LLL artery and the main pulmonary artery. During regional hypoxia without sevoflurane, blood flow distribution to the LLL as a mean was 48.2% of that determined under hyperoxic conditions. When sevoflurane was administered at concentrations of 2% and 4%, the LLL blood flow distributions during hypoxia were as a mean 40.2% and 47.0%, respectively, of the values obtained during the first hyperoxic periods. No change occurred in the pulmonary vascular resistance of the LLL(PVR(LLL)) and the shunt ratio(Qs/Qt) between the concentrations used. Thus there was no significant effect of sevoflurane upon HPV whatever concentration used.