What do flow volume loops represent?
) displays airflow (in L/second) as it relates to lung volume (in L) during maximal inspiration from complete exhalation (residual volume [RV]) and during maximum expiration from complete inhalation (TLC).
How do you think lung volume as seen on a flow volume loop would be affected by restrictive lung disorders?
Flow-volume loops in restrictive lung disease If the restrictive disease did nothing but reduce the volume of the lung, the curve would look rather normal, but diminished in size, as depicted below. However, usually the lung disease also causes a decrease in lung compliance.
What are flow loops?
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 maneuvers. Changes in the contour of the loop can aid in the diagnosis and localization of airway obstruction [1].
What is a respiratory flow volume loop?
What is peak expiratory flow rate used for?
Peak flow measurement is a quick test to measure air flowing out of the lungs. The measurement is also called the peak expiratory flow rate (PEFR) or the peak expiratory flow (PEF). Peak flow measurement is mostly done by people who have asthma.
Why does expiratory flow decrease with decreasing lung volume?
The equal pressure point moves peripherally (toward smaller airways) as lung volume decreases during a forced expiration; hence the resistance of small airways limits maximal expiratory flow more at low than at high lung volumes.
Why is it harder to exhale than inhale with asthma?
When things are working normally, the amount of air we breathe in is about the same as the amount of air we breathe out. But during an asthma attack, air gets trapped inside the lungs making it harder and harder to breathe.
What are the features of the flow-volume loop?
Characteristic features of restrictive lung disease in the flow-volume loop include the following: 1 Low tidal volume 2 Rapid decrease in inspiratory flow 3 Rapid expiratory flow, with a high peak expiratory flow rate (as the inelastic lung recoils) More
Why is the inspiratory flow part of the loop?
The inspiratory flow part of the loop is therefore more reflective of lung compliance: as the lung distends, the flow decreases. Then, the patient exhales passively; here airway resistance will be revealed as the determinant of expiratory flow rate.
How is the normal expiratory flow-volume curve characterized?
The normal expiratory portion of the flow-volume curve is characterized by a rapid rise to the peak flow rate, followed by a nearly linear fall in flow as the patient exhales toward RV (figure 2).
How does obstructive lung disease affect the flow volume loop?
Characteristic features of obstructive lung disease in the flow-volume loop include the following: If the restrictive disease did nothing but reduce the volume of the lung, the curve would look rather normal, but diminished in size, as depicted below. However, usually the lung disease also causes a decrease in lung compliance.