Pharmacokinetic Study Of The Intravenous Application Of Emulsified Isoflurane

Objective To determine the minimum alveolar concentration of emulsified isoflurane (8%, vol/vol) by intravenous administration (MACiv), and compared it with the minimum alveolar concentration of isoflurane by inhalation approach (MACinh)Methods Twelve healthy adult mongrel dogs were assigned randomly and equally to intravenous anesthesia group (Giv) with emulsified isoflurane and inhalation anesthesia group (Ginh) with isoflurane vapor. A method of up-and-down and stimulation of tail clamping were applied to determine MACiv in the Giv and MACinh in the Ginh, respectively. Isoflurane concentration and partial pressure in the end tidal gas, femoral arterial blood and jugular venous blood were measured simultaneously just before each tail clamping and during recovery.Results The induction time of Giv(105 ±24 sec.) was shorter than that of Ginh (378+102 sec). During induction, the consumed liquid isoflurane in the Giv (1.8ml) was less than that in the Ginh (9.8 ml, P<0.01). The MACiv (1.12% ±0.18%) was significantly smaller than the MACinh (1.38%±0.16%, P<0.05). The infused volume of lipid emulsion had a positive linear correlation with the isoflurane blood/gas partition coefficient (r2=0.883). No significant differences were found in the awaking end tidal isoflurane concentration and the awaking time between the two groups (P>0.05).Conclusion The MAC of intravenous emulsified isoflurane was smaller than that of inhaled isoflurane vapor in dogs. Emulsified isoflurane holds the characteristics of total intravenous anesthesia and total inhaled anesthesia.