System and method for preventing cross-contamination in flow generation systems

A ventilator system comprising:

• an airflow generator connected in-line to a humidifier, which is connected in line to a first check valve, which is connected in line to a patient interface connection by an inhalation flow circuit;
• a controller electrically coupled to the airflow generator;
• a second check valve connected in-line to a bacterial filter along an exhalation flow circuit, the exhalation flow circuit connected to the inhalation flow circuit between a first junction upstream of the humidifier and a second junction downstream of the first check valve, so as to prevent cross-contamination between the inhalation and exhalation flow circuits;
• and
• an exhalation valve electrically coupled to the controller and connected to the inhalation flow circuit downstream of the airflow generator and upstream of the humidifier.