# I:E relation

## Overview

The I:E relation is sometimes also described as the duty cycle or percent inspiration ([Tobin2013] p.150). A duty cycle describes the time spend in an active state as a fraction of the total time. In mechanical ventilation the active time corresponds to the inspiration time and the total time to the time of the respective respiratory cycle.The I:E relation is expressed as a percentage. The larger the relation, the longer is the inspiratory time in relation to the total respiratory cycle time.

In some ventilation modes the I:E relation is an input parameter, see [Rimensberger2015] p.1439 or it can be set indirectly via the inspiration time Ti, see [Tobin2013] p.87. Different ventilation modes employ characteristic I:E ratios.

## Details

The inspiration:expiration relation time is calculated in the RIP app for each respiratory cycle, based on the breath detections of the RC signal. For convenience the inspiration time is always set to 1, that results in a ration of 1:x, with x=expiration time (s)/ inspiration time (s). The expiration time is x times longer than the inspiration time.The inspiration time is the time between an inspiratory- and the following expiratory onset. Respectively the expiration time is the time between an expiratory- and an inspiratory onset.