Extent and practicalities of filter use in anaesthetic breathing circuits and attitudes towards their use: a postal survey of UK hospitals.

A postal survey of 120 UK hospitals was conducted to assess the current use of filters in anaesthetic breathing systems and consultant anaesthetists' opinion of their value; 76% of the questionnaires were returned complete. The survey showed that 77.2% of anaesthetic departments use a new filter for every case, a variety of different filter types being used. A connector distal to the filter was used in 78.3% of patients, providing a possible route for cross infection. Anaesthetists rated the prevention of bacterial infection and gross contamination as being higher priorities than the prevention of viral infection. Of those surveyed, 66.3% believed filters were worthwhile whereas only 35.9% thought they were cost effective. Only 34.8% of anaesthetists believed that the supposed extra efficiency of pleated hydrophobic membrane filters over electrostatic filters merited their extra cost.