A HMEF and HEPA filter should be inserted for each patient to avoid cross-contamination and to ensure maximal safety for the healthcare workers.

Add a HMEF filter close to the patient, and HEPA filter close to the one-way valve on each expiratory circuit. 

HMEF filters become moist over time, and their effectiveness deteriorates. To make sure the healthcare workers are protected at all times, an extra HEPA filter is needed.

Example image of HMEF filter inserted proximally to test lung (center, blue). Image by Dr. Mergeay.

The International Workgroup on Differential Multiventilation


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