Breathing Circuit

An exercise non re-breathing valve allows air to be inhaled through the pneumotach and then vented through a mixing chamber where the expired gas is presented for analysis.

Recurring Gas Sampling Sequence

At the start of each minute room air is purged through the gas sampling circuit and analysed for ambient (ie. inspired) oxygen and carbon dioxide concentration (FiO2) and (FiCO2). This period can be set between 10 and 25 seconds. Note that during this phase Ve continues to be measured, expired gas continues to be mixed and the chamber ‘updated’, but measurements are not reported.

After the room air purge period, expired gas is drawn from the mixing chamber for analysis. VO2 is updated and displayed after each breath.

Predictive Sampling Option

When selected this option predicts minute VO2 after each breath. The prediction improves as the minute sampling interval progresses.