Notice the smooth upswing from zero during initial expiration's early phase and then the flow drops off. The part of the loop under the horizontal axis is the flow during inspiration.
5.2 flow volume loops
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This is a normal flow volume loop. Notice the smooth upswing from zero during initial expiration's early phase and then the flow drops off. The part of the loop under the horizontal axis is the flow during inspiration. |
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This shape of loop almost always tested on in EVERY exam
that it can be tested in. It is diagnostic of tracheal stenosis. It
is called a donut shaped flow loop. Notice how 1) expiration is delayed, 2) the peak flow is less and 3) the inspiratory loop (one under the horizontal axis) is almost identical to the expiratory flow loop (the one over the horizontal). |
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The Shape of this loop is also frequently asked on tests. This is for obstructive lung disease. It means that this loop could signify any one of the following 3 things: Chronic bronchitis, Asthma or emphysema.. If the dip in the second half (downsloping part) of the expiration is reversed by bronchodilators, it is likely asthma or reversible component of chronic bronchitis. If it is not, it is chronic obstructive lung disease. |