Supine-Dependent Changes in Upper Airway Size in Awake Obstructive Sleep Apnea Patients

ABSTRACT

The purpose of this study was to define the changes in upper airway size in response to a body position change from upright to supine. A total of 15 male Caucasian obstructive sleep apnea (OSA) patients with a mean apnea hypopnea index of 31.0 ± 13.9/hr were recruited for this study. A set of upright and supine cephalograms was traced and digitized for each patient. The most constricted site in the upright position was located in the velopharynx. When the body position was changed from upright to supine, a significant reduction in the anteroposterior dimension was observed only at the level of the velopharynx (p < 0.05). Sagittal cross-sectional areas of the velopharynx and the oropharynx significantly decreased (p < 0.05), but the soft palate area increased (p < 0.05). We conclude that the velopharynx is not only the narrowest site in both upright and supine body positions but also the most changeable site in response to an alteration in body position during wakefulness. Backward displacement of the soft palate with a change in shape may reflect less functional compensation in the velopharynx than that in the oropharynx and the hypopharynx and partly explain why upper airway occlusion occurs primarily in the velopharynx in OSA patients.

KEYWORDS

Obstructive sleep apnea - upper airway - body position - cephalometry

REFERENCES

• 1 Remmers J E, de Groot J W, Sauerland E K, Anch A M. Pathogenesis of upper airway obstruction during sleep.  J Appl Physiol . 1978;  44 931-938
• 2 Pae E K. A size and shape analysis in obstructive sleep apnea patients [dissertation]. Vancouver, BC: The University of British Columbia; 1993
• 3 Kokich V. What's new in dentistry.  Angle Orthod . 2000;  70 413-414
• 4 Kuna S T, Remmers J E. Anatomy and physiology of upper airway obstruction. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine 3rd ed. Philadelphia: WB Saunders 2000: 840-858
• 5 Lowe A A. Oral appliances for sleep breathing disorders. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine 3rd ed. Philadelphia: WB Saunders 2000: 929-939
• 6 Findley L J, Suratt P M. Serious motor vehicle crashes: the cost of untreated sleep apnoea.  Thorax . 2001;  56 505
• 7 Cartwright R D. Effects of sleep position on sleep apnea severity.  Sleep . 1984;  7 110-114
• 8 McEvoy R D, Sharp D J, Thornton A T. The effects of posture on obstructive sleep apnea.  Am Rev Respir Dis . 1986;  133 662-666
• 9 Elliot A R, Shea S A, Dijk D J. et al . Microgravity reduces sleep-disordered breathing in humans.  Am J Respir Crit Care Med . 2001;  164 478-485
• 10 Horner R L. Motor control of the pharyngeal musculature and implications for the pathogenesis of obstructive sleep apnea.  Sleep . 1996;  19 827-853
• 11 Miyamoto K, Özbek M M, Lowe A A, Fleetham J A. Effect of body positions on tongue posture in awake patients with obstructive sleep apnoea.  Thorax . 1997;  52 255-259
• 12 Mathur R, Mortimore I L, Jan M A, Douglas N J. Effect of breathing, pressure and posture on palatoglossal tone.  Clin Sci (Colch) . 1995;  89 441-445
• 13 Solow B, Tallgren A. Head posture and craniofacial morphology.  Am J Phys Anthropol . 1976;  44 417-436
• 14 Tsuiki S, Hiyama S, Ono T. et al . Effects of a titratable oral appliance on supine airway size in awake non-apneic individuals.  Sleep . 2001;  24 554-560
• 15 Hiyama S, Ono T, Ishiwata Y, Kuroda T. Supine cephalometric study on sleep-related changes in upper-airway structures in normal subjects.  Sleep . 2000;  23 783-790
• 16 Hair J F, Anderson R E, Tatham R L, Black W C. Preparing for a multivariate analysis. In: Hair JF, Anderson RE, Tatham RL, Black WC, eds. Multivariate Data Analysis 5th ed. Englewood Cliffs, NJ: Prentice-Hall 1988: 33-86
• 17 Jan M A, Marshall I, Douglas N J. Effect of posture on upper-airway dimensions in normal human.  Am J Respir Crit Care Med . 1994;  149 145-148
• 18 Pracharktam N, Hans M G, Strohl K P, Redline S. Upright and supine cephalometric evaluation of obstructive sleep apnea syndrome and snoring subjects.  Angle Orthod . 1994;  64 63-74
• 19 Martin S E, Mathur R, Marshall I, Douglas N J. The effect of age, sex, obesity and posture on upper airway size.  Eur Respir J . 1997;  10 2087-2090
• 20 Tsuiki S, Ono T, Kuroda T. Mandibular advancement modulates respiratory-related genioglossus electromyographic activity.  Sleep Breathing . 2000;  4 53-57
• 21 Tsuiki S, Ono T, Ishiwata Y, Kuroda T. Functional divergence of genioglossus motor unit with respiratory-related activity.  Eur Respir J . 2000;  15 906-910
• 22 Malhotra A, Pillar G, Fogel R B. et al . Genioglossal but not palatal muscle activity relates closely to pharyngeal pressure.  Am J Respir Crit Care Med . 2000;  162 1058-1062
• 23 Morrison D L, Launois S H, Isono S. et al . Pharyngeal narrowing and closing pressures in patients with obstructive sleep apnea.  Am Rev Respir Dis . 1993;  148 606-611
• 24 Van de Graaff B W, Gotteried S B, Mitra J, Van Lunteren E, Cherniack N S, Strohl K P. Respiratory function of hyoid muscles and hyoid arch.  J Appl Physiol . 1984;  57 197-204
• 25 Lowe A A, Gionhaku N, Takeuchi K, Fleetham J A. Three-dimensional CT reconstructions of tongue and airway in adult subjects with obstructive sleep apnea.  Am J Orthod Dentofacial Orthop . 1986;  90 364-374
• 26 Lowe A A, Fleetham J A. Two- and three-dimensional analyses of tongue, airway and soft palate size. In: Norton ML, Brown ACD, eds. Atlas of the Difficult Airway St. Louis, MO: Mosby 1991: 74-82
• 27 Pae E K. Cephalometry needs innovation, not renovation.  Angle Orthod . 1997;  67 395-396
• 28 Cakirer B, Hans M G, Graham G, Aylor J, Tishler P V, Redline S. The relationship between craniofacial morphology and obstructive sleep apnea in Whites and in African-Americans.  Am J Respir Crit Care Med . 2001;  163 947-950
• 29 Liu Y, Lowe A A, Zeng X, Fu M, Fleetham J A. Cephalometric comparisons between Chinese and Caucasian patients with obstructive sleep apnea.  Am J Orthod Dentofacial Orthop . 2000;  117 479-485
• 30 Schmidt-Nowara W. Recent developments in oral appliance therapy of sleep disordered breathing.  Sleep Breathing . 1999;  3 103-106
• 31 de Almeida R F, Bittencourt L R, de Almeida I C, Tsuiki S, Lowe A A, Tufik S. Effects of mandibular posture on obstructive sleep apnea severity and the temporomandibular joint in patients fitted with an oral appliance.  Sleep . 2002;  25 507-513
• 32 Liu Y, Lowe A A, Fleetham J A, Park Y. Cephalometric and physiological predictors of the efficacy of an adjustable oral appliance for the treatment of obstructive sleep apnea.  Am J Orthod Dentofacial Orthop . 2001;  120 639-647