Fig 2. Switch use during swallowing under NIV.

The patient withholds mechanical ventilation at the end of the inspiratory cycle by activating the switch and starts to swallow (plain arrow). The end of swallowing is followed by a reopening of the glottis which generates a positive pressure in the upper airways (shallow arrow) and by a spontaneous expiration of the patient as evidenced by the thoracic and abdominal movements. The patient then resumes his mechanical ventilation by deactivating the switch.