Humidification devices

Abstract 

Because dry gases can damage respiratory mucosa, lung structure and function, gases need to be humidified for mechanically ventilated patients. Heat and moisture exchangers (HMEs) are the most commonly used humidification devices. They are inexpensive and simple, with additional bacterial and viral filtration properties. Although different brands of HMEs can seem to be similar, the humidification efficiency varies widely. The best performing, achieving absolute humidity of more than 30 mg/l, are often composite hygroscopic HMEs. These are appropriate devices for many patients on critical care units. The limited humidification efficiency of many HMEs makes them appropriate only for short-term use in anaesthesia. Hot water humidifiers (HWHs) are capable of delivering inspired gases at 37°C or higher, with humidity at saturation. The disadvantages of HWHs are that they are bulky, complex pieces of equipment with high maintenance costs. There is limited evidence of any significant difference in mortality, duration of mechanical ventilation, length of stay, incidence of ventilator-associated pneumonia or incidence of airway occlusion between the different categories of humidification device. In patients who have very viscous secretions, HWHs with a set temperature greater than 37.0°C should be given preference.

Keywords: heat and moisture exchanger, humidification device, humidifier, humidity, nebulizer