A ventilator or fluid
delivery system that provides a flow of gas to an
airway of a user. The ventilator includes a source of gas (30, 32), a conduit (63, 65, 42) that carries the flow of gas to the
airway of a patient, a first valve (38, 40) that controls a pressure, flow, or volume, of the flow of gas, a
pressure sensor (46) operatively coupled to the conduit between the valve and the patient and adapted to monitor a pressure of the gas in the conduit, and a controller (50) adapted to control the valve based on an output of the
pressure sensor The ventilator further includes a restrictor (62) provided in the conduit between the
pressure sensor and the patient. The restrictor, in essence, divides the fluid
delivery system such that a first volume is defined in the conduit between the valve and the restrictor and a second volume is defined in the conduit between the patient and the restrictor, wherein the first volume is less than the second volume. The
control system controls the pressure, flow, or volume relative to the first volume so that an accurate, fast, and stable control of the pressure, flow, or volume is achieved.