Effect of negative expiratory pressure (nep) on respiratory system
flow resistance in awake snorers and non-snorers.
Tantucci, Claudio, Alexandre Duguet, Anna Ferretti, Selma Mehiri,
Isabelle Arnulf, Marc Zelter, Thomas Similowski, Jean-Philippe
Derenne, and Joseph Milic-Emili.
Clinica di Semeiotica Medica, University of Ancona, 60020 Ancona,
Italy; Laboratoire de Physio-Pathologie Respiratoire et Service de
Explorations Fonctionnelles, Groupe Hospitalier Piti[acute]e
-Salp[circumflex]etri[grave]ere, University of Paris VI, Paris, Cedex
13, France; Servizio di Pneumologia, Ospedale Sant'Orsola, 40100
Bologna, Italy; and Meakins-Christie Laboratories, McGill University,
Montreal, Qu[acute]ebec, Canada H2Z 2P2
APStracts 6:0255A, 1999.
In spontaneously breathing subjects intrathoracic expiratory flow
limitation can be detected by applying a negative pressure (NEP) at
the mouth during tidal expiration. To assess if NEP might increase
per se the upper airway resistance, expiratory airway resistance
(Rint,rs) was computed with and without NEP by using the interrupter
technique in 12 awake, healthy subjects, 6 non-snorers and 6 non
-apneic snorers. Expiratory flow (V) and Rint,rs were measured under
control conditions with V increased voluntarly and during random
application of brief (0.2 s) NEP pulses from -1 to -7 cmH2O, in both
seated and supine position. In non-snorers Rint,rs with spontaneous
increase in V and with NEP was similar. At spontaneous V of 1.0+0.01
L/s Rint,rs was 3.10+0.19 cmH2O/L/s, while at V of 1.1+0.07 L/s with
NEP (-5 cmH2O) Rint,rs amounted to 3.30+0.18 cmH2O/L/s. In snorers a
marked increase of Rint,rs was found at all levels of NEP (p<0.05).
At spontaneous V of 0.81+0.02 L/s Rint,rs was 3.50+0.44 cmH2O/L/s,
while at V of 0.80+0.17 L/s with NEP (-5 cmH2O) Rint,rs amounted to
8.97+3.16 cmH2O/L/s (p<0.05). With NEP Rint,rs was markedly higher
in snorers than in non-snorers both seated (F=8.77; p<0.01) and
supine (F=9.43; p<0.01). In snorers V increased much less with NEP
than in non-snorers and was sometimes lower than without NEP,
especially in the supine position. This study indicates that during
wakefulness non-apneic snorers have more collapsible upper airways
than non-snorers, as reflected by the marked increase of Rint,rs with
NEP. The latter leads occasionally to an actual decrease of V such as
to invalidate the NEP method for detection of intrathoracic
expiratory flow limitation.
Received 2 November 1998; accepted in final form 5 May 1999.
APS Manuscript Number A1000-8.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1999 The American Physiological Society.
Published in APStracts on 14 June 1999