PMC5487400_01
Pictures from the videolaryngoscopy taken immediately after exercise showing the vocal cord adduction in inspiration (left) and abduction in expiration (right).
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F1
The paradoxical vocal cord adduction during inspiration and abduction during expiration are illustrated in Figure 1.
Baseline recording of tidal flow (V', dotted line):inspiration upward:and respiratory resistance (Rrs, bold line). The tracings are superimposed to emphasize the normal Rrs variation that follows the absolute value of flow in both inspiration and expiration.
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F2
The time course of Rrs at baseline showed the expected slight flow-dependent increase during both inspiration and expiration (Figure 2).
Recording of flow (V', dotted line) and respiratory resistance (Rrs, bold line) 5 min after exercise shows first a normal Rrs pattern for three breaths. The transient interruption of expiratory flow at fourth breath (arrow) is followed by a dramatic increase in Rrs during the following inspiration that also shows flow limitation. The pattern is continued for the next inspirations. Note transient interruptions of Rrs trace due to the filtering procedure.
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F3
A few minutes after exercise, while less labored and somewhat more regular breathing had resumed, Rrs showed first a normal pattern for a few breaths, but when airflow was briefly interrupted in expiration:probably with swallowing:a sudden, large increase in Rrs occurred in inspiration (Figure 3), a pattern that continued throughout the acquisition, especially not resolving with the deep breath. For instance, after alteration in the tidal expiratory flow suggestive of swallowing (Figure 3), the laryngeal obstruction was reinitiated.
Recording of flow (V', dotted line), tidal volume (V, light), and respiratory resistance (Rrs, bold line) 15 min after exercise. The normal Rrs pattern is dramatically altered after the deep breath. A large increase in Rrs in inspiration occurs during the next few breaths. Also note inspiratory flow limitation on first breath after deep inhalation.
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F4
The assessment 15 min after exercise also showed at first a normal pattern, but the deep inhalation was associated with major and irregular increase in Rrs in inspiration (Figure 4). Also, there were indications throughout the post-exercise period that deep inhalation would re-induce intermittent laryngeal closure in inspiration (Figure 4).