Comment humidifier les voies aériennes chez les patients ventilés en réanimation ?

Humidification and warming of inspired gas are physiological functions of upper airways aiming to preserve the lower airway mucosa. Otherwise, the patient is exposed to the risk of airway obstruction, atelectasis and pneumonia. These functions are bypassed in patients ventilated with an endotracheal tube, and are potentially insufficient in patient treated with non invasive ventilation, and sometimes in non-mechanically ventilated patients treated by receiving oxygen high flow. Heated humidifiers are the most efficient humidification and warming devices but also the most expensive ones and the less easy to use, compared to heat and moisture exchangers (also called “filters” because of their frequent antimicrobial filter property). The two types of devices, that are now available, have been technically improved and there is no evidence to recommend or prohibit at the present time the use of one device or the other. There is especially no risk of nosocomial pneumonia associated with the use of an heated humidifier, contrarily to early devices. Use of a “filter” is determined firstly by its heat and moisture exchange capacity. Humidification function of some available “filters” may be insufficient or add a large dead space. “Filters” performances should be checked by independent assessment and known by physician before their purchase. If the routine use of “filters” has been chosen because of their cost and their simplicity of use, cost-effectiveness should be taken into account that they must been changed regularly and that they are insufficient in several clinical situations, which have to be well-known.