STUDY OBJECTIVES: Previous studies in both awake and sleeping humans have demonstrated that lung-volume changes substantially affect upper-airway size and pharyngeal resistance and, thus, may influence pharyngeal patency. We sought to systematically investigate the isolated effects of lung-volume changes on pharyngeal collapsibility and mechanics and genioglossus muscle activation during stable non-rapid eye movement sleep. We hypothesized that lower lung volumes would lead to increased pharyngeal collapsibility, airflow resistance, and, in compensation, augmented genioglossus muscle activation. DESIGN: Nineteen normal individuals (age, 30.4 +/- 0.5 years; body mass index: 24.5 +/- 0.4 kg/m2) were studied during stable non-rapid eye movement sleep in a rigid head-out shell equipped with a variable positive/negative pressure attachment for manipulations of extrathoracic pressure and, thus, lung volume. SETTING: Sleep physiology laboratory. PARTICIPANTS: Normal healthy volunteers. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: We measured change in end-expiratory lung volume (EELV) (magnetometers), genioglossus electromyogram (GGEMG) (intramuscular electrodes), pharyngeal pressure, and collapsibility of the pharynx in response to a brief pulse of negative pressure (-8 to -15 cm H2O) under the following conditions: (1) baseline, (2) increased EELV (+1 liter), and (3) decreased EELV (-0.6 liter). Reduced lung volumes led to increased inspiratory airflow resistance (7.54 +/- 2.80 cm H2O x L(-1) x s(-1) vs 4.53 +/- 1.05 cm H2O x L(-1) x s(-1), mean +/- SEM, P = 0.02) and increased genioglossus muscle activation (GGEMG peak 14.6% +/- 1.5% of maximum vs 8.6% +/- 1.5% of maximum, maximum P = 0.001) compared to baseline. The pharynx was also more collapsible at low lung volumes (4.3 +/- 0.5 cm H2O vs 5.4 +/- 0.6 cm H2O, P = 0.04). CONCLUSIONS: We conclude that upper-airway muscles respond to changes in lung volumes but not adequately to prevent increased collapsibility. These results suggest that lung volume has an important influence on pharyngeal patency during non-rapid eye movement sleep in normal individuals.
STUDY OBJECTIVES: Previous studies in both awake and sleeping humans have demonstrated that lung-volume changes substantially affect upper-airway size and pharyngeal resistance and, thus, may influence pharyngeal patency. We sought to systematically investigate the isolated effects of lung-volume changes on pharyngeal collapsibility and mechanics and genioglossus muscle activation during stable non-rapid eye movement sleep. We hypothesized that lower lung volumes would lead to increased pharyngeal collapsibility, airflow resistance, and, in compensation, augmented genioglossus muscle activation. DESIGN: Nineteen normal individuals (age, 30.4 +/- 0.5 years; body mass index: 24.5 +/- 0.4 kg/m2) were studied during stable non-rapid eye movement sleep in a rigid head-out shell equipped with a variable positive/negative pressure attachment for manipulations of extrathoracic pressure and, thus, lung volume. SETTING: Sleep physiology laboratory. PARTICIPANTS: Normal healthy volunteers. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: We measured change in end-expiratory lung volume (EELV) (magnetometers), genioglossus electromyogram (GGEMG) (intramuscular electrodes), pharyngeal pressure, and collapsibility of the pharynx in response to a brief pulse of negative pressure (-8 to -15 cm H2O) under the following conditions: (1) baseline, (2) increased EELV (+1 liter), and (3) decreased EELV (-0.6 liter). Reduced lung volumes led to increased inspiratory airflow resistance (7.54 +/- 2.80 cm H2O x L(-1) x s(-1) vs 4.53 +/- 1.05 cm H2O x L(-1) x s(-1), mean +/- SEM, P = 0.02) and increased genioglossus muscle activation (GGEMG peak 14.6% +/- 1.5% of maximum vs 8.6% +/- 1.5% of maximum, maximum P = 0.001) compared to baseline. The pharynx was also more collapsible at low lung volumes (4.3 +/- 0.5 cm H2O vs 5.4 +/- 0.6 cm H2O, P = 0.04). CONCLUSIONS: We conclude that upper-airway muscles respond to changes in lung volumes but not adequately to prevent increased collapsibility. These results suggest that lung volume has an important influence on pharyngeal patency during non-rapid eye movement sleep in normal individuals.
Authors: Amy S Jordan; David P White; Robert L Owens; Danny J Eckert; Shilpa Rahangdale; Susie Yim-Yeh; Atul Malhotra Journal: J Appl Physiol (1985) Date: 2010-05-27
Authors: Yu-Lun Lo; Amy S Jordan; Atul Malhotra; Andrew Wellman; Raphael A Heinzer; Matthias Eikermann; Karen Schory; Louise Dover; David P White Journal: Thorax Date: 2007-03-27 Impact factor: 9.139
Authors: Raphael C Heinzer; Michael L Stanchina; Atul Malhotra; Robert B Fogel; Sanjay R Patel; Amy S Jordan; Karen Schory; David P White Journal: Am J Respir Crit Care Med Date: 2005-04-07 Impact factor: 21.405
Authors: Simon A Joosten; Bradley A Edwards; Andrew Wellman; Anthony Turton; Elizabeth M Skuza; Philip J Berger; Garun S Hamilton Journal: Sleep Date: 2015-09-01 Impact factor: 5.849
Authors: Amy S Jordan; David P White; Yu-Lun Lo; Andrew Wellman; Danny J Eckert; Susie Yim-Yeh; Matthias Eikermann; Scott A Smith; Karen E Stevenson; Atul Malhotra Journal: Sleep Date: 2009-03 Impact factor: 5.849