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1 Circadian, Neuroendocrine, and Sleep
Disorders Section, Pulmonary and Critical Division, and
2 Endocrine-Hypertension Division, Department of
Medicine, Brigham and Women's Hospital, Harvard Medical School,
Boston, Massachusetts 02115
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.
upper airway dilator muscles; genioglossus muscle; pharyngeal
muscles; neuromuscular adaptation; electromyogram; obstructive sleep
apnea