Heat and Moisture Exchangers (HME) are devices used in mechanically ventilated patients intended to help prevent complications due to "drying of the respiratory mucosa, such as mucus plugging and endotracheal tube (ETT) occlusion. HMEs are one type of commercial humidification system, which also includes non-heated-wire humidifiers and heated-wire humidifiers. HMEs have been in clinical use for over 30 years. An HME cassette plays a central part in lung rehabilitation after a total laryngectomy.