Portex Thermovent T2 heat and moisture exchanger (HME) Sterile, single use heat and moisture exchanger. Provides effective humidification for spontaneously breathing patients whose upper airways are bypassed by a tracheostomy tube. Device can be used for a maximum period of 24 hours. Now there is a new oxygen accessory line available. The Thermovent T2 Oxygen Line is a specific designated oxygen tube for use with the Portex Thermovent T2.