The upper respiratory tract is an effective system of conditioning inspired air, the water content is usually less than 25% which is warmed and humidified through the nose, by the time it reaches the nasopharynx it has been warmed to approx 37oC and is fully saturated.

The upper airway of a tracheostomy patient has been by – passed, this affects the warming and humidification of air and the defence mechanisms i.e. coughing and mucocillary transport are adversely affected therefore the lack of nasal warming and humidification will cause drying of tracheobronchial secretions and mucosa, the effect of this is that patients with a tracheostomy can become prone to:

• Atelectasis
• Pulmonary Infection
• Respiratory obstruction
  

(Line drawings of respiratory tract in normal breathing and tracheostomised patient)

The Methods of Humidification

1. Cold Water Devices
2. Hot Water Humidifiers
3. Heat & Moisture Exchanges [ HME ]
4. Moist Gauze / Tracheal Bib
5. Nebuliser.

(Photos around text demonstrating various humidification devices)

References
Griggs A 1998 Tracheostomy : Humidification Nursing standard.