Restrepo RD, Walsh BK (2012) Humidification during invasive and noninvasive mechanical ventilation: 2012. Respiratory Care 57: 782-788.
When the upper airway is bypassed during invasive mechanical ventilation, humidification is necessary to prevent hypothermia, disruption of the airway epithelium, bronchospasm, atelectasis, and airway obstruction. In severe cases, inspissation of airway secretions may cause occlusion of the endotracheal tube. While there is not clear consensus on whether or not additional heat and humidity are always necessary when the upper airway is not bypassed, such as in noninvasive mechanical ventilation (NIV), active humidification is highly suggested to improve comfort.