An evaluation of the microbial retention performance of three ventilator-circuit filters.

OBJECTIVES

to determine and compare the microbial retention efficiency of 3 types of heat and moisture exchange (HME) filters.

DESIGN

randomised prospective study.

SETTING

Intensive Care Unit at the Middlesex Hospital and the microbiology laboratory of the Department of Academic Microbiology, University College London Medical School.

MEASUREMENTS AND RESULTS

An aerosol challenge to each filter using a suspension containing. S. marcescens and the bacteriophage MS2. In total 45 filters of 3 types were tested, 15 previously unused and 30 that had been used in ventilator circuits of 30 patients. The 3 types of filter generally had microbial retention efficiencies of > 99.99% for both S. marcescens and the bacteriophage MS2.

CONCLUSION

The 3 types of HME filter were effective microbial filters and comparable in their microbial retention.