title: Filters reduce the risk of bacterial transmission from contaminated heated humidifiers used with CPAP for obstructive sleep apnea.
abstract: BACKGROUND
  The treatment of choice for obstructive sleep apnea (OSA) is nasal continuous positive airway pressure (nCPAP) during sleep, but dryness of the upper airway compromises compliance. Heated humidifiers may mitigate such noncompliance; however, recent observations suggest that their use, particularly if not cleaned, increases the risk of respiratory infections. Humidifier water may be contaminated, but the long-held view that passive humidifiers cannot aerosolize water may obscure the perception of risk of infection.
  
  
  OBJECTIVE
  This study challenges the long-held view that "passover" humidifiers do not aerosolize water. With such evidence, this study characterizes the performance of filters to reduce the potential risk of contamination.
  
  
  METHODS
  Heated humidifier water contaminated with bacteria was studied under conditions simulating week-long use of nCPAP for OSA.
  
  
  RESULTS
  Bacteria were recovered in 9 of 11 tests from the breathing tubes of CPAP devices fitted with heated humidifiers with water contaminated with Brevundimonas diminuta or Serratia marcescens. Recoverable bacteria ranged from tens to thousands of colony forming units when tested at air flow rates of 60 liters per minute for 90 minutes. Neither organism was recovered from the circuit tubing when a hydrophobic breathing-circuit filter was positioned between the humidifier and face-mask tubing with a commercially available nCPAP machine tested under simulated-use conditions.
  
  
  CONCLUSIONS
  Data suggest that patients with OSA being treated with nCPAP fitted with humidifiers may be aerosolizing bacteria, putting them at risk for developing respiratory infections and that the use of a hydrophobic filter may attenuate the passage of microbes from contaminated humidifier water.
authors.affiliation: Pall Corporation, East Hills, NY 11548, USA. Jerry_Ortolano@pall.com
authors.forename: Girolamo A
authors.initials: GA
authors.lastname: Ortolano
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Schaffer
authors.forename: Morven B
authors.initials: MB
authors.lastname: McAlister
authors.forename: Ilia
authors.initials: I
authors.lastname: Stanchfield
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Hill
authors.forename: Liliana
authors.initials: L
authors.lastname: Vandenburgh
authors.forename: Michelle
authors.initials: M
authors.lastname: Lewis
authors.forename: Shirnett
authors.initials: S
authors.lastname: John
authors.forename: Francis P
authors.initials: FP
authors.lastname: Canonica
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Cervia
mesh_terms: D000336:Aerosols; D001424:Bacterial Infections / Q000382:microbiology / Q000517:prevention & control*; D001431:Bacteriological Techniques; D042063:Caulobacteraceae / Q000254:growth & development; D015169:Colony Count, Microbial; D003114:Colony-Forming Units Assay; D045422:Continuous Positive Airway Pressure / Q000295:instrumentation*; D004867:Equipment Design; D006361:Heating; D006801:Humans; D006813:Humidity; D008851:Micropore Filters; D012141:Respiratory Tract Infections / Q000382:microbiology / Q000517:prevention & control / Q000635:transmission*; D012706:Serratia marcescens / Q000254:growth & development; D014871:Water Microbiology
chemical_list: D000336:Aerosols