Comparative ex vivo study on humidifying function of three speaking valves with integrated heat and moisture exchanger for tracheotomised patients

Objective Assessment of humidifying function of tracheotomy speaking valves with integrated heat and moisture exchanger. Design Ex vivo measurement of water exchange and storage capacity of three tracheotomy speaking valves: Humidiphon Plus, Spiro and ProTrach DualCare (with two different heat and moisture exchangers: XtraMoist and Regular). Setting Comprehensive Cancer Centre. Participant Healthy volunteer. Main outcome measures Difference between end-inspiratory and end-expiratory weight as measure for water exchange capacity, weight after 10 min breathing as measure for water storage capacity, weighing at 1-min intervals to assess residual water exchange potential in speaking mode and absolute humidity in mg/L as measure for environmental and respiratory humidity. Results None of the tracheotomy speaking valves provides humidification while in speaking mode. Only the ProTrach DualCare allows blocking the speaking valve and breathing through the heat and moisture exchanger during inhalation and exhalation (heat and moisture exchanger mode). This leads to an increase in inspiratory humidity of 2.5 mg (XtraMoist) and 1.6 mg (Regular). There was no measurable water storage in speaking mode in any of the three tracheotomy speaking valves. In breathing mode, water storage in the DualCare heat and moisture exchangers was 47 and 37 mg, respectively. The remaining humidifying potential in speaking mode after 10 min breathing in heat and moisture exchanger mode for XtraMoist was 38%, 15% and 10% at 1, 2 and 3 min, respectively. For Regular, this was 47%, 24% and 13%, respectively. Conclusions Tracheostoma valves with integrated heat and moisture exchanger have no humidification function in speaking mode. Only ProTrach DualCare, allowing blocking the speaking mode, in heat and moisture exchanger mode enables a significant increase in humidification. Regular switching between speaking and heat and moisture exchanger mode with this latter device prolongs the humidification in speaking mode