Humidifier, Respiratory Gas

This chapter discusses the purpose, principle of operation, specifications, and applications of respiratory gas humidifier. Respiratory gas humidifiers are used for artificially conditioning respiratory gas for the patient during mechanical ventilation therapy. Respiratory humidification can be achieved using either a heat and moisture exchanger or a heated humidifier. Heated humidifiers are active humidification systems that operate actively to increase the heat and water vapour content of the inspired gas. Heated humidifiers operate in invasive humidification mode and noninvasive humidification mode. Most of the modern humidifiers are servo-controlled in which the desired gas temperature is set by the operator. The temperature of the gas is maintained by the controller irrespective of the changes in gas flow or reservoir level. Respiratory humidifiers are used to provide optimum humidity to respiratory gases delivered to patients via endotracheal tubes or face masks. Respiratory humidifiers find applications in patients with newly formed tracheostomies.