[Artificial humidification of inspired gas--status of knowledge and technique]

Artificial humidification of inspired air serves to maintain or restore physiological heat and moisture conditions in the bronchial system in intubated or tracheotomized patients. The need to condition the respiratory gases in these patients is undisputed. The present paper reviews the pathophysiology and methods of the artificial active and passive humidifying of inspired gases. The various advantages and disadvantages of the individual methods and techniques of humidifying inspired gases are compared and discussed. Present-day medical knowledge indicates that passive artificial humidifying of respiratory gases (heat and moisture exchanger, HME) is adequate to meet most requirements for warming and moistening the inspiratory air in patients whose upper airways are devoid of natural conditioning of respiratory gases in consequence of intubation and tracheotomy. This applies to artificial ventilation in prehospital situations, artificial ventilation in anaesthesia and long-term artificial ventilation on the intensive care unit. With appropriate restrictions, the respiratory air of patients who breathe spontaneously via an artificial air vent (e.g. tracheal cannula) can also be conditioned by HME.