HUMIDIFIER

Typical Number in Hospital: 50

Cost Bands: 2

References: 2

During anaesthesia or artificial ventilation the body's natural humidification processes are often bypassed, with the result that there is a drying out of the trachea and larger bronchi. Humidifiers can be classified as follows:

1. Passive humidifiers such as the 'artificial nose'

2. True water vapour humidifiers, or nebulizers producing droplets of water

3. Hot or cold humidifiers

4. Those intended for humidifying the atmosphere or those intended for connection to an airway.

The mechanism of humidification may involve bubbling the gases through a bottle of water, or the use of a wick, atomizer, ultrasound, or hot water.

The temperature of the delivered gases and their handling on the way to the patient is most important since 100% relative humidity at room temperature may fall to 30% when the gases have been warmed in the lungs. With nebulizers the drop size is important since large drops will only serve to waterlog the lungs without the moisture reaching the alveoli.