Humidification of patients breathing spontaneously in a teaching hospital

Abstract

The nose and upper airway act to heat and moisturise inspired air. The point at which inspired air reaches 37°C and 100% relative humidity is normally just below the carina. If the noise and upper airway are by-passed by a tracheal tube or tracheostomy then cold, dry gases are delivered to the lungs. As the bronchial tree is lined with mucus secreting, ciliated epithelium the effect of such cold, dry gases is to damage muco-ciliary function leading to impaired sputum clearance and ultimately pneumonia. Humidification may also be given to other patients, even if they do not have an artificial airway, in order to improve their comfort. In the past this has usually been provided with hot water humidification.1 This form of humidification heats water and the inspired gas allowing a greater amount of water to be contained in the inspired gas. Recently, there has been a move away from these devices to disposable equipment that bubble a high pressure mixture of oxygen and air through water. Some water will be va...