Sterile water is unnecessary in a continuous positive airway pressure convection-type humidifier in the treatment of obstructive sleep apnea syndrome.
OBJECTIVE
We investigated the necessity of using sterile water in humidifiers for avoiding respiratory tract infections during nasal continuous positive airway pressure (nCPAP) therapy.


METHODS
Water in a convection-type humidifier (Sirius; Heinen and Löwenstein GmbH; Bad Ems, Germany) was labeled with (99m)Tc-diethylenetriamine penta-acetic acid. Low-flow (2 L/min, 4 L/min, or 6 L/min) and high-flow (31 to 46 L/min) rates were applied, rates typical for nCPAP. Heat and moisture exchange filters were placed behind the start of the tube to measure any radioactive aerosol.


RESULTS
We demonstrated that no radioactive aerosols were produced, either with low or high flows.


CONCLUSIONS
The convection-type humidifier produces water vapor but does not aerosolize the water. We conclude that bacteria, other microorganisms, or even solutes that may be contained in the water cannot be transported into the air and thus will not be deposited in the lung. In order to avoid respiratory tract infections, sterile water is not required, at least in this particular humidifier. We suggest that nonsterile tap water is probably a safe alternative.
Wenzel
Markus
M
Annostr. 1, Krankenhaus Kloster Grafschaft, Zentrum für Pneumologie, Beatmungs- und Schlafmedizin, D-57392 Schmallenberg, Germany.
Klauke
Matthias
M
Gessenhardt
Frank
F
Dellweg
Dominic
D
Haidl
Peter
P
Schönhofer
Bernd
B
Köhler
Dieter
D
D000336:Aerosols; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D006801:Humans; D012891:Sleep Apnea Syndromes / Q000628:therapy*; D013242:Sterilization; D014867:Water / Q000592:standards*
D000336:Aerosols; D014867:Water