Heated humidifiers compared to heat and moisture exchangers for ventilated adults and children

When mechanical ventilation is used to keep critically ill people breathing effectively, the upper airway must be humidified by artificial means. Heated humidification and heat and moisture exchangers are the most commonly used methods of artificial humidification. We undertook this review to determine whether either of these methods of humidification was more effective than the other in preventing complications in people who are being mechanically ventilated. When data from the 33 included trials, with 2833 participants, were analysed there was some evidence that the prevalence of pneumonia may be lowered by using heat and moisture exchangers that capture less moisture. A heat and moisture exchanger may however also increase blockage of the artificial airway. Findings of this review are limited by the considerable differences between studies and there was little information about these methods of humidification in children.