Abstract: A system for determining total flow output from a flow generator, and/or tidal volume of gas inhaled by a patient includes: a flow generator for connection to a patient interface; a patient pressure sensor to measure patient pressure at the patient interface and an oxygen input line with an oxygen input line sensor, both in communication with a controller. The oxygen input line conveys oxygen from an oxygen source to the flow generator, and has an oxygen flow valve for controlling the flow of oxygen from the oxygen source to the flow generator. The processor is programmed with one or more algorithms to determine the flow output for the flow generator based on a particular patient pressure and oxygen input line flow. Leak flow is subtracted from the flow generator output to determine patient flow, which is integrated to calculate patient tidal volume of gas inhaled.

Abstract: An adaptor for generating flow includes an adaptor housing body. The distal end of the body has an oxygen inlet that extends extending into an interior of a distal air intake portion. The oxygen inlet has a nozzle with at least two apertures for directing oxygen into an interior of a distal air intake portion. The distal air intake portion includes at least one air inlet port to allow air to be drawn into the interior of the distal air intake portion, and a flow-resisting media covering at least a portion of the at least one air inlet port.