Sevoflurane output from the Oxford Miniature Vaporizer in drawover mode

The sevoflurane output from the Oxford Miniature Vaporizer (OMV) was measured in a series of bench tests in a drawover system. Using a range of settings on two OMVs in series, output ranged from 0.5 to 5.9% with a 600 ml tidal volume at a rate of 12 breaths/min produced by a Penlon Multivent. The OMVs' output was steady over 40 minutes. In tests with tidal volumes ranging from 300 ml to 1200 ml, the OMVs' output was lower at higher minute volumes. When continuous flow of carrier gas at 7.2 l/min was used, the output was lower than at the equivalent intermittent flow rate. Using two OMVs with a drawover system appears to be a feasible technique for the induction and maintenance of sevoflurane anaesthesia. Clinical tests of sevoflurane drawover anaesthesia are now required so that the advantages of sevoflurane can gain wider application in field and military anaesthesia.