Ventilation assistance

A method of using a ventilation assistance device for providing ventilation to a subject, the method comprising the steps of:

• using a duct of the ventilation assistance device for establishing fluid communication between a source of gas and an interface device for delivering gas to the subject's airway;
• using a flow sensor of the ventilation assistance device to calculate a volume of gas received by the subject based on determining a flow volume of gas in the duct;
• using an operator interface of the ventilation assistance device to represent the calculated volume of gas received by the subject by way of a plurality of indicators, each indicator being representative one of a plurality of reference subject groups having respective characteristics, wherein the operator interface is configured to determine, based on the calculated volume of gas received by the subject, for which one of the plurality of reference subject groups the calculated volume of gas received by the subject is suitable, and to display one of the plurality of indicators to represent to an operator the characteristic of the reference subject group for which the calculated volume of gas received by the subject has been determined to be suitable;
• and
• the operator maintaining a current operation mode of performing the ventilation assistance if the characteristic of the reference subject group for which the calculated volume of gas received by the subject is suitable matches the subject or adjusting the current operation mode of performing the ventilation assistance if otherwise.