The anesthetic and physiologic effects of an intravenous administration ofa halothane lipid emulsion (5% vol/vol)

The IV administration of less than or equal to 9 mL of nonvaporized liquid halothane causes significant pulmonary damage, cardiovascular decompensatio n, and death. To determine whether liquid halothane mixed in a lipid emulsi on would alter these toxic effects, six swine were evaluated in a randomize d cross-over study. The pulmonary, analgesic, hemodynamic, and histopatholo gic effects of liquid halothane (25 mL) mixed with a liquid carrier (475 mL , Liposyn III 20%) and administered by constant infusion were compared with halothane administered by a calibrated vaporizer. Three swine received the halothane lipid emulsion (HLE), followed by inhaled halothane. Three addit ional swine received inhaled halothane, followed by the HLE. There were no changes in pulmonary compliance or arterial blood gases during or after the administration of equivalent volumes of halothane (13.75 mL) either by inf usion of HLE or by inhalation of halothane. The end-tidal halothane concent ration for the minimum alveolar anesthetic concentration was 0.79% +/- 0.08 % during HLE administration and 1.13% +/- 0.12% for inhaled halothane (P < 0.001). Hemodynamic variables and blood halothane levels by gas chromatogra phy were measured at end-tidal concentrations of 0.6%, 1.2%, and 1.8%. Bloo d halothane levels (mg/mL) were significantly higher (P < 0.05) after the a dministration of HLE at end-tidal halothane concentrations of 1.2% (0.49 +/ - 0.19 vs 0.82 +/- 0.18) and 1.8% (0.79 +/- 0.17 vs 1.29 +/- 0.34). When co mpared at equivalent blood levels, HLE caused fewer changes in the left ven tricular end-diastolic pressure, mean arterial pressure, and dP/dt than inh aled halothane. There was no evidence of pulmonary histopathologic damage 4 -8 h after the infusion of 500-700 mt of HLE. This novel method of delivery of a volatile anesthetic seems to lack the toxicity of direct IV administr ation of liquid halothane. It may be a useful alternative to traditional ad ministration via a vaporizer. Implications: Halothane causes pulmonary dysf unction and death when given IV in liquid form. Six swine received a haloth ane lipid emulsion IV to evaluate the anesthetic and physiologic effects. N o pulmonary toxicity or deaths were associated with the halothane lipid emu lsion. The anesthetic profile was similar to delivery of halothane via a va porizer.