normal flow volume loop has a rapid peak expiratory flow rate with a gradual decline in
flow back to zero. The inspiratory portion of the loop is a deep curve plotted on the
negative portion of the flow axis. Inspiratory data is often overlooked, but the flow
volume loop gives the opportunity of assessing this information as well.
The normal volume time curve has a rapid upslope and approaches a
plateau soon after exhalation. The maximum volume attained represents the forced vital
capacity (FVC), while the volume attained after one second represents the forced
expiratory volume (FEV1).