Heat and Moisture Exchange Filters in Respiratory Support

Introduction to HME Filters

Heat and Moisture Exchange (HME) filters function by collecting heat and moisture from a patient's expired air and returning it to the inspired air, providing passive humidification while potentially filtering viral particles, making them preferable to heated humidification systems which can aerosolize pathogens 1, 2

HMEs are strongly preferred over heated humidification (HH) systems in patients with infectious respiratory conditions, as HH involves open flow of humidified air which can aerosolize viral particles 1, 2
A Cochrane review of 33 trials (n=2833) showed equivalence between HH and HMEs in adequacy of humidification and prevalence of occlusion 1
HMEs should be placed immediately when disconnecting from closed-circuit ventilation systems to minimize aerosolization of potentially infectious particles 1, 3

Not all HMEs can filter viral particles, and some lack oxygen ports 1, 2
HMEs can be difficult to breathe through and may require frequent changes due to accumulation of secretions 1

For patients with infectious respiratory conditions, use HMEs with viral filters that have filtration efficiency >99.9% and bidirectional design 1
In mechanically-ventilated patients, suspend positive-pressure ventilation before disconnecting ventilator circuits from tracheostomy tubes and place an HME device with viral filter on the tube in the interim 1, 2
Change HMEs when they malfunction mechanically or become visibly soiled, but not routinely more frequently than every 48 hours 4
If HME is unavailable and there is high risk of mucus plugging in a patient with a single cannula tube, consider instilling saline drops through the inline suction port with scheduled suctioning to reduce mucus buildup 1, 3
All discarded HMEs should be considered infectious and disposed of quickly and properly 1