A method of operating a ventilator assembly having inhalation and exhalation passages communicating with one another, and a respiration assembly that can perform repetitive respiratory cycles. The method includes (a) connecting the conduit with an open end of an endotracheal tube positioned within the trachea so that the open end leads into the airway below the vocal cords, (b) repetitively cycling the respiration assembly so that during the inhalation phase, gas in the inhalation passage flows through the endotracheal tube and into the airway, and during the exhalation phase, an exhalation valve is maintained relatively closed and the exhaled gases flow pass the vocal cords and out of the mouth thereby facilitating the patients ability to speak, and (c) monitoring ring the pressure within at least one of the passages during both phases for determining the pressure within the patient for use in operating the ventilator assembly.
