The bacterial and viral filtration performance of breathing system filters*

Abstract

The bacterial and viral filtration performance of 12 breathing system filters was determined using test methods specified in the draft European standard for breathing system filters, BS EN 13328‐1. All the filters were of two types, either pleated hydrophobic or electrostatic, and these two types differed in their filtration performance. The filtration performance is expressed in terms of the microbial penetration value, defined as the number of microbes passing through the filter per 10 million microbes in the challenge. The geometric mean (95% confidence limits) microbial penetration value was 1.0 (0.5, 3.5) and 2390 (617, 10 000) for the pleated hydrophobic and electrostatic filters, respectively, for the bacterial challenge, and 87 (48, 212) and 32 600 (10 900, 84 900), respectively, for the viral challenge. In general, there was little change in the microbial penetration values following 24 h simulated use. It is concluded that results from the tests specified in the draft standard will allow comparisons to be made between different manufacturers’ products enabling an informed choice to be made.

Measuring the filtration performance of breathing system filters using sodium chloride particles*

“…A filter (the HMEF1000) that had a geometric mean filtration efficiency of 95% when challenged with sodium chloride particles in the present study (with some of the five filters tested having a filtration efficiency of less than 95%) had a filtration efficiency of 99.86% when challenged with an aerosol of Bacillus subtilis var niger using the same flow of air [8]. However, a filter (the Clear-Therm) with a filtration efficiency of 97% in the present study had a bacterial filtration efficiency of 99.997% when challenged with an aerosol of B. subtilis var niger [8]. Therefore, the CDC requirement that the filtration efficiency must be at least 95% appears to imply a bacterial filtration efficiency of at least 99.9% when challenging the filter with B. subtilis var niger.…”

“…Therefore, the CDC requirement that the filtration efficiency must be at least 95% appears to imply a bacterial filtration efficiency of at least 99.9% when challenging the filter with B. subtilis var niger. In contrast, the efficiency of pleated hydrophobic filters was generally at least 99.9999% when challenged with B. subtilis var niger [8]. As M. tuberculosis is larger than B. subtilis var niger, the filtration efficiency against M. tuberculosis should be even greater.…”

Evaluation of the Approaches of the Anaesthesiologists on Maintenance of Anaesthesia Machines

“…Vaporizatörlerin kalibrasyonu çok hassas bir iştir ve sadece üretici firma yetkilileri tarafından yapılmalıdır (23 (25). Bununla birlikte ventilatör ilişkili pnömoniyi önlemede etkili oldukları ispatlanamamıştır (26).…”

The reuse of anesthesia breathing systems: another difference of opinion and practice between the United States and Europe

“…Breathing filters that also prevent the inhalation of microorganisms are usually referred to as HME filters (HME-F). Laboratory studies show that breathing filters have a microbial penetration value, defined as the number of microbes passing through the filter per 10 million microbes, as low as 1.2 for bacteria and 89 for viruses, which corresponds to a filtration efficiency of 99.9999 and 99.9991%, respectively [11]. The filtration performance of pleated hydrophobic membrane filters is greater than that of electrostatic filters.…”