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Do in-line respiratory filters protect patients? Comparing bacterial removal efficiency of six filters

Anne-Marie Canakis1, Bernard Ho, Sharon Ho

  • 1Division of Respiratory Medicine, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.

Pediatric Pulmonology
|October 3, 2002
PubMed

Insights

Bacterial removal efficiency (BRE) varied significantly among six hospital filters tested. Some filters maintained 100% BRE, while others showed reduced performance, highlighting critical differences in infection control for respiratory equipment.

Area of Science:

  • Medical Microbiology
  • Biomedical Engineering
  • Infection Control

Background:

  • Cross-infection is a significant concern with respiratory equipment, particularly for cystic fibrosis patients undergoing pulmonary function tests.
  • Effective filtration is crucial for preventing microbial transmission in healthcare settings.

Purpose of the Study:

  • To evaluate and compare the bacterial removal efficiency (BRE) of six different filters used in pulmonary function diagnostics and ventilator circuits.
  • To identify the bacterial thresholds of these filters, indicating the concentration at which 100% BRE is compromised.

Main Methods:

  • Six hospital filters (Microgard, Spirobac, PALL, KOKO, Clear-Guard, Respigard) were tested for BRE using a Pseudomonas aeruginosa suspension.
  • Filters were challenged under saturated and non-saturated conditions, with and without peak flow application.
  • Bacterial colony-forming units (CFU) downstream from each filter were counted to determine BRE and bacterial thresholds.

Main Results:

  • Significant differences in BRE were observed among filters, especially in saturated states at a challenge of 1 x 10(4) CFU/mL.
  • Four filters (MG, KK, CG, RG) demonstrated 100% BRE, while Spirobac (98.8%) and PALL (42.7%) showed lower efficiency.
  • Filter bacterial thresholds varied widely, with KOKO having the highest (1 x 10(8) CFU/mL) and Spirobac/PALL the lowest (<1 x 10(4) CFU/mL).

Conclusions:

  • The study confirms significant variations in the bacterial removal capabilities of commonly used hospital respiratory filters.
  • Filter performance can be compromised under specific conditions, underscoring the need for careful selection based on intended use and potential microbial load.
  • These findings have implications for infection control strategies in pulmonary diagnostics and respiratory therapy.

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