CoughAssist Disposable Filter Overview AG T70 Expiratory Bacteria Filter prevents foreign material from entering the device and transferring to the patient. AG Industries Inline Bacteria Filter is compatible with a number of different machines,including the Philips Respironics Trilogy Ventilator. This filter attaches to the Trilogy between the tubing and the device itself. It helps prevent bacteria and viruses from being inhaled by the user. This creates a sterile environment for airflow while also keeping users healthy. These filters can be replaced approximately every 30 days or until blocked by moisture or mucus. Do not attempt to wash these filters. They come one per pack. The filter can be left in place as long as it is not blocked by sputum or trapped moisture.