Filters reduce the risk of bacterial transmission from contaminated heated humidifiers used with CPAP for obstructive sleep apnea.
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.
Ortolano
Girolamo A
GA
Pall Corporation, East Hills, NY 11548, USA. Jerry_Ortolano@pall.com
Schaffer
Jeffrey
J
McAlister
Morven B
MB
Stanchfield
Ilia
I
Hill
Elizabeth
E
Vandenburgh
Liliana
L
Lewis
Michelle
M
John
Shirnett
S
Canonica
Francis P
FP
Cervia
Joseph S
JS
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
D000336:Aerosols