Table 2.

Advantages and disadvantages of active and passive humidification systems

	Advantages	Disadvantages
Active humidifiers	They do not have contraindications. As they are placed in the inspiratory branch, they do not add instrumental dead space. If used correctly, they do not increase the resistance. They have alarm systems. They are more efficient and can deliver accurate temperatures.	Possibility of electrocution of the patient and the operator. They expose the airway lesion to excessive temperature. The presence of water in the circuit can limit the airflow. Condensation generates changes in the airway pressure and can lead to asynchronies. Colonization of the circuit. They require more monitoring to ensure correct performance.
	Advantages	Disadvantages
Passive humidifiers	Their use is simple. They do not have risks related to the treatment equipment. They are light in weight. They are cheaper. They are easily available in the intensive care unit.	They are contraindicated in some pathologies or clinical conditions. Because they are placed before the 'Y' in the circuit, they increase the instrumental dead space. They increase the resistance (negligible in most cases). They have lower performance or efficiency compared with an active humidifier. They should be retired to be able to apply aerosol therapy (except Gibeck Humid-Flo HME®).