Reduced genioglossal activity with upper airway anesthesia in awake patients with OSA.

We examined whether topical upper airway anesthesia leads to a reduction in genioglossal (GG) electromyogram (EMG) in patients with obstructive sleep apnea (OSA). Airway mechanics were also evaluated. In 13 patients with OSA, we monitored GG EMG during tidal breathing and during the application of pulses of negative airway pressure (-10 to -12 cmH(2)O). Airflow resistance and airway collapsibility were determined. All measurements were performed with and without topical anesthesia (lidocaine). Anesthesia led to a significant fall in the peak GG EMG response to negative pressure from 36.1 +/- 4.7 to 24.8 +/- 5.3% (SE) of maximum (P < 0.01). This was associated with a fall in phasic and tonic EMG during tidal breathing (phasic from 24.4 +/- 4.1 to 16.4 +/- 3.4% of maximum and tonic from 10.9 +/- 1.6 to 8.0 +/- 1.3% of maximum, P < 0.01). A significant rise in pharyngeal airflow resistance was also observed. Our results demonstrate that topical receptor mechanisms in the nasopharynx importantly influence dilator muscle activity and are likely important in driving the augmented dilator muscle activity seen in the apnea patient.