A new keyed vaporizer filler.

A new design of keyed filler with a dead space of 1.1 ml was used with 50 bottles of isoflurane to fill vaporizers. The volume of isoflurane remaining in the 'empty' bottle, the residual volume, was measured. The trial was repeated using the old style filler which has a dead space of 3.3 ml. The new filler reduced the mean residual volume by 73% but still did not completely empty the bottle.