Known oxygen concentrator systems for delivering oxygen enriched gas to a user may fail to adequately account for erratic breathing patterns of the user. This may require artificial “blind periods” to be created when using known systems. The present invention comprises an oxygen concentrator apparatus configured to automatically measure the time between a plurality of successive breaths and determine an average breathing rate based on the time between each breath of the plurality of successive breaths, wherein the time between a penultimate breath and a last breath of the plurality of successive breaths is not used to determine the average breathing rate. In discarding information pertaining to the last measured breath from the determination of average breathing rate, the present invention provides a way to take into account a user’s erratic breathing patterns without the need to create artificial “blind periods”.
