Abstract: 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.