Influence of upper airway pressure oscillations on soft palate
muscle electromyographic activity.
Brancatisano, A., T. Van Der Touw, N. O'neill, and T. C. Amis.
Department of Respiratory Medicine, Westmead Hospital, Westmead,
NSW, Australia, 2145
APStracts 3:0193A, 1996.
Snoring is characterised by high frequency (30-50Hz) pressure
oscillations (HFPO) in the upper airway (UA). The soft palate is a
major oscillating structure during snoring and soft palate muscle
(SPM) activity is an important determinant of velopharyngeal patency.
Consequently, we examined the effect of artificial HFPO applied to
the UA on the integrated electromyographic activity (EMG) of the SPMs
in 11 supine, mouth closed, anaesthetised (sodium
pentobarbitone/chloralose) dogs breathing spontaneously via a
tracheostomy. The EMGs of the palatinus (PAL, n=11), levator veli
palatini (LP, n=9), and tensor veli palatini (TP, n=8) were monitored
with intramuscular fine wire electrodes. Peak inspiratory (PI) and
peak expiratory (PE) EMG activity was measured in arbitrary units
(a.u.) as the mean of 5 consecutive breaths. HFPO (+/- 4.5+/-0.4
cmH2O, mean+/-SEM; 30Hz) applied at the laryngeal end of the isolated
UA increased PI EMG from 3.3+/-2.0 to 8.4+/-1.7 a.u. (P<0.05)
for PAL, and from 2.0+/-1.1 to 7.3+/-2.7 a.u. (P<0.05) for LP.
For the TP, increases were evident in 4 dogs but mean values for the
group did not change (5.8+/-2.4 to 11.0+/-4.1 a.u., P=0.5). The PE
EMG did not change for any SPM (all P>0.3). Thus, HFPO applied
to the UA augments inspiratory SPM activity. Reflex augmentation of
SPM activity by HFPO may serve to dilate the retropalatal airway
and/or stiffen the soft palate during inspiration in an attempt to
stabilise UA geometry during snoring.
Received 6 December 1995; accepted in final form 1 April 1996.
APS Manuscript Number A1265-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96