Flow/volume and volume/time graphs

**The flow-volume loop** is a plot of inspiratory and expiratory flow (on the Y-axis) against volume (on the X-axis) during the performance of maximally forced inspiratory and expiratory manoeuvres.

**The volume/time graph** is a plot of volume on the vertical Y axis against time on the horizontal X axis.

These are the pictures of spirometry and useful in assessing the validity (acceptability and repeatability) of each and every blow as well as looking at the size and shape of each graph to assist in interpreting results.

*Figure 5.6: Examples flow / volume and volume / time graphs showing the key measurements graphically (www.sibelmed.com)*

Below the flow/volume and volume / time graphs show the workerâ€™s actual blow (solid green and blue lines) against the lower and upper levels of normal, LLN -1.64 and ULN in the grey dotted lines. The predicted PEFR and FVC (Z score 0) are shown on the flow / volume graph and the predicted FEV_{1}, FEV6 and FVC (Z score 0) on the volume / time graph (blue dots).

Looking at these graphs without even seeing the numerical values, It is clear to see that this worker has smaller volumes and flow rates than what is expected for his or her age, height, sex and race.

*Figure 5.7: Examples real life flow / volume and volume / time graphs*

Login

Accessing this course requires a login. Please enter your credentials below!