Retention of airborne latex particles by a bacterial and viral filter used in anaesthesia apparatus.

We have developed a series of laboratory tests to evaluate the efficiency of a heat and moisture exchanger filter (Pall BB25) in retaining latex particles in order to protect allergic patients during anaesthesia. Latex particles were nebulised with cornstarch as a support and collected for assay in a flask, with or without the filter integrated into the experimental circuit. With the Pall BB25 filter in the circuit, no natural latex proteins were detected by measurement of either total protein or antigenic latex proteins. The Pall BB25 filter may represent a useful means of preventing inhalation of latex particles during anaesthesia in susceptible patients.