Abstract: In some examples, a ventilator includes a pneumatic connection configured to receive supply gas; an inspiratory path configured to deliver conditioned gas to lungs of a patient; a valve pneumatically connected to the pneumatic connection and configured to allow flow of the supply gas to the inspiratory path when the valve is open and block flow of the supply gas to the inspiratory path when the valve is closed; a pressure sensor configured to measure a pressure of the supply gas at the pneumatic connection; and electronic control circuitry configured to control an opening and closing of the valve based on the measured pressure to produce a desired volume of conditioned gas in the inspiratory path.