Effects of Different Concentrations of Sevoflurane Anaesthesia on Blood Free Hexafluoroisopropanol Levels and Anaesthesia Awakening Period in Adult Rats

Abstract Background: Sevoflurane is metabolized in the body to Hexafluoro-isopropanol(HFIP). The aim of this study was to compare the levels of free HFIP in the blood of rats after inhalation of different concentrations of sevoflurane and the effects on the awakening period of rats, and to investigate the related mechanisms. Methods: Seventy-four healthy male rats of 8–10 weeks of age were selected. Six rats were used to determine the blood/gas partition coefficient of HFIP. Forty-eight rats were randomly divided into three groups: 0.5 minimum alveolar concentration (MAC) (group S1), 1.0 MAC (group S2), and 1.5 MAC (group S3), with 16 rats in each group. The free HFIP concentration in blood was measured by gas chromatography. Twenty rats were randomly divided into five groupsof four rats each, anesthetized by inhalation of 1.0 MAC sevoflurane for mine field tests, and immunohistochemistry was used to detect glial changes in cognition-related brain regions of rats. Results: The peak concentration of free HFIP in the blood of rats appeared at an inhalation concentration of 1 MAC (P<0.05), and the total mileage of the mine experiment was the longest in rats anesthetized for 1 h with 1.0 MAC sevoflurane (P<0.05).Expression of glial fibrillary acidic protein (GFAP) and IBA1 in cognitively related brain regions was significantly higher in rats anesthetized for 1 h with 1.0 MAC sevoflurane than the other time points (P<0.05). Conclusions: Free HFIP in the blood of rats reached its peak 1 hour after 1.0 MAC sevoflurane anesthesia was inhaled. Rats showed obvious arousal and excitement at this time, and glial cells and inflammatory factors in cognitively related brain regions were significantly activated.