Am. J. Respir. Crit. Care Med.,
Volume 165, Number 8, April 2002, 1055-1061
Mechanical Properties of the Lung and Upper Airways
in Patients with Sleep-disordered Breathing
Eve L.
Bijaoui,
Victoria
Champagne,
Pierre F.
Baconnier,
R. John
Kimoff,
and
Jason H. T.
Bates
Meakins-Christie Laboratories, McGill University; Respiratory Division, Royal Victoria Hospital-MUHC, Montreal, Canada; TIMC IMAG Laboratory,
UMR CNRS, Grenoble, France; and Vermont Lung Center, Department of Medicine, University of Vermont, Burlington, Vermont
We studied the changes in lung and upper airway mechanics in
adult human subjects with obstructive sleep apnea/hypopnea syndrome (OSAHS) during wakefulness, sleep, and at arousal from
sleep. We used two numerical methods that we have previously developed specifically for dealing with inspiratory flow limitation during sleep: the modified Mead-Whittenberger method, and information-weighted histograms obtained using recursive least squares.
Full polysomnography including esophageal pressure and airflow
measurements was performed in seven men with OSAHS (respiratory disturbance index: 55.8 ± 23.2 events/h). Pharyngeal pressure
was recorded in four of the subjects to partition lung mechanics
into its upper airway and lower lung components. Both techniques
showed that total lung resistance and elastance increased significantly (p < 0.05) during obstructed breathing and that this increase
was reversed at the end of the obstruction. The partitioning of mechanics showed that upper airway collapse was primarily responsible for the increase in lung resistance. Our results suggest that
OSAHS may lead to transient abnormalities in the recruitment of
lung units and the gas exchanging capacity of the lungs.
