Room temperature bubble-through water chambers for patient oxygen supply are an infection hazard and do not provide significant humidification!

These commonly used devices are usually contaminated with environmental Gram negative bacteria that like moist environments – eg. Pseudomonas species, Alcaligenes, coliforms and other. These organisms may be multi-resistant.  The physics of humidification show that these room temperature devices do NOT significantly increase the humidity of the gas. Furthermore, patients on short-term low-flow oxygen therapy via mask or nasal prongs do NOT require humidification of oxygen – this is definitely not a practice followed in developed world situations. There are high flow oxygen circuits used, but these have heated humidification chambers with sterile water added, managed under strict asepsis.


Darin J et al. Respir Care. 1982 Jan;27(1):41-50. An evaluation of water-vapor output from four brands of unheated, prefilled bubble humidifiers.

Weber MW et al.  Pediatr Pulmonol. 1996 Aug;22(2):125-8. Humidification of oxygen with unheated humidifiers in tropical climates.

I’d be keen to hear of your views !  If you use the devices, then get your lab to culture the water to see what is there – you will be horrified!

About mdjkf

Microbiologist and Infectious Diseases Physician
This entry was posted in Cautionary tales, Infection prev & control, Med Micro topics-advanced and tagged , , , . Bookmark the permalink.

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