Ventilatory Control and Airway Anatomy in Obstructive Sleep Apnea

• Published in: American journal of respiratory and critical care medicine 2004-12, Vol.170 (11), p.1225-1232
• Main Authors: Wellman, Andrew, Jordan, Amy S, Malhotra, Atul, Fogel, Robert B, Katz, Eliot S, Schory, Karen, Edwards, Jill K, White, David P
• Format: Article
• Language: English
• Subjects: Adult; Airway management; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Apnea - physiopathology; Biological and medical sciences; Biomechanical Phenomena; Chronic obstructive pulmonary disease, asthma; Emergency and intensive respiratory care; Eye movements; Feedback; Female; Humans; Intensive care medicine; Male; Medical sciences; Middle Aged; Pharynx - anatomy & histology; Pharynx - physiopathology; Pneumology; Polysomnography; Pulmonary Ventilation - physiology; Regression analysis; Respiration; Sleep apnea; Sleep Apnea, Obstructive - physiopathology; Sleep Stages; Ventilators
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/rccm.200404-510OC

Ventilatory instability may play an important role in the pathogenesis of obstructive sleep apnea. We hypothesized that the influence of ventilatory instability in this disorder would vary depending on the underlying collapsibility of the upper airway. To test this hypothesis, we correlated loop gain with apnea-hypopnea index during supine, nonrapid eye movement sleep in three groups of patients with obstructive sleep apnea based on pharyngeal closing pressure: negative pressure group (pharyngeal closing pressure less than -1 cm H(2)O), atmospheric pressure group (between -1 and +1 cm H(2)O), and positive pressure group (greater than +1 cm H(2)O). Loop gain was measured by sequentially increasing proportional assist ventilation until periodic breathing developed, which occurred in 24 of 25 subjects. Mean loop gain for all three groups was 0.37 +/- 0.11. A significant correlation was found between loop gain and apnea-hypopnea index in the atmospheric group only (r = 0.88, p = 0.0016). We conclude that loop gain has a substantial impact on apnea severity in certain patients with sleep apnea, particularly those with a pharyngeal closing pressure near atmospheric.