The ventilation filters protect the patient, staff and equipment from microbial contamination, since both the expiratory and inspiratory air is filtered. The fields are in a position to effectively filter out any kind of particles and bacteria from the respiratory gas. The ventilation filters are deployed in anesthesia, intensive care and rescue services and have a filter efficiency of up to 99.99995%.

They also serve as heat and moisture exchangers, which is why they are also called HME filters (Heat and Moisture Exchangers). Over-humidification of respiratory gas is prevented, since the filter stores only the moisture from the expired air and releases it again during inhalation.