Assessment of three filters for respiratory function tests.

Several filters specific for respiratory function tests have been on the ma rket for several years. Recommended by the manufacturers to avoid contamina ting the equipment and thus improve patient safely, these filters require a considerable financial investment. We studied the passage of diluted blood into artificial saliva in a patient model simulating inspiration tests and rapid forced expiration to assess the retention capacity of three filters used for respiratory function tests: Multi SPIRO MI-90016 (MultiSPIRO), PF 30S (Pall Biomedical) and Spirobac (Dar.S.p.A). The mean percentage of pass age was 1.48% through the MI-90016 filter, 57.15% through the PF 30 S filte r and 70.45% through the Spirobac filter. These findings provide further el ements for choosing filters for respiratory function tests. Indeed, despite the manufacturers' commercial arguments, the technical documents provided do not give necessary information on the filtering capacity of the filters on the market. We have observed that two out of the three filters tested do no meet the standards expected by clinicians.