Background: There is more than one mechanism which contributes to the increases in upper airway resistance in obstructive sleep apnea and hypopnea syndrome. Impulse oscillation provides a convenient way of noninvasive monitoring and differentiating the contributions of airway resistance. Objective: To evaluate the effect of posture on airway resistance in obstructive sleep apnea-hypopnea syndrome (OSAHS) by means of impulse oscillation. Methods: Ten subjects without OSAHS proved by polysomnography served as controls, 14 patients with mild or moderate OSAHS and another 20 severe OSAHS patients were studied. All subjects underwent an overnight sleep study. Airway resistance was measured by impulse oscillometry, and spirometry was performed in the seated position and then in the supine position while awake. Results: Compared with controls, the severe and the mild-moderate OSAHS groups had significantly bigger changes in Zrs, Rrs5, R20 and R35 due to posture. There were also significant differences in R10, R15 and R25 between the severe OSAHS and the control groups. Besides, the group differences between the severe and the mild-moderate groups regarding the magnitude of this change were not significant. The correlation coefficients between apnea/hypopnea index and Zrs, R5 and R20 in supine position were 0.487, 0.486 and 0.485, respectively. Conclusion: The magnitude of change in airway resistance due to posture is bigger in OSAHS than in non-OSAHS. Zrs, R5 and R20 in supine position were associated moderately with apnea/hypopnea index.

Keywords:
Obstructive sleep apnea-hypopnea syndrome, Impulse oscillation, Airway resistance, Posture
1.
Strollo PJ Jr, Rogers RM: Obstructive sleep apnea. N Engl J Med 1996;334:99–104.
2.
Flemons WW: Obstructive sleep apnea. N Engl J Med 2002;347:498–504.
3.
Suratt PM, McTier RF, Wilhoit SC: Collapsibility of the nasopharyngeal airway in obstructive sleep apnea. Am Rev Respir Dis 1985;132:967–971.
4.
Hudgel DW: Mechanisms of obstructive sleep apnea. Chest 1992;101:541–549.
5.
Hora F, Nápolis LM, Daltro C, et al: Clinical, anthropometric and upper airway anatomic characteristics of obese patients with obstructive sleep apnea syndrome. Respiration 2007;74:517–524.
6.
Tvinnereim M, Mateika S, Cole P, Haight J, Hoffstein V: Diagnosis of obstructive sleep apnea using a portable transducer catheter. Am J Respir Crit Care Med 1995;152:775–779.
7.
Oostveen E, Macleod D, Lorino H, Farre R, Hantos Z, Desager K, Marchal F, ERS Task Force on Respiratory Impedance Measurements: The forced oscillation technique in clinical practice: methodology, recommendations and future developments. Eur Respir J 2003;22:1026–1041.
8.
Zhu L, Liu YN, Yu RJ: Clinical Lung Function. Beijing, People’s Medical Publishing House, 2004, pp 263–281.
9.
Cauberghs M, Van de Woestijne KP: Mechanical properties of the upper airway. J Appl Physiol 1983;55:335–342.
10.
Reisch S, Schneider M, Timmer J, Geiger K, Guttmann J: Evaluation of forced oscillation technique for early detection of airway obstruction in sleep apnea: a model study. Technol Health Care 1998;6:245–257.
11.
Navajas D, Farre R, Rotger M, Badia R, Puig-de-Morales M, Montserrat JM: Assessment of airflow obstruction during CPAP by means of forced oscillation in patients with sleep apnea. Am J Respir Crit Care Med 1998;157:1526–1530.
12.
Ficker JH, Wiest GH, Asshoff G, Fuchs FS, Schmelzer AH, Harsch IA, Hahn EG: Sensitivity of a simplified forced oscillation technique for detection of upper airway obstruction. Respir Physiol 2001;124:243–249.
13.
Lorino AM, Lofaso F, Dahan E, Harf A, Lorino H: Respiratory impedance response to continuous negative airway pressure in awake controls and OSAS. Eur Respir J 2001;17:71–78.
14.
Badia JR, Farre R, Montserrat JM, et al: Forced oscillation technique for the evaluation of the sleep apnea hypopnea syndrome: a pilot study. Eur Respir J 1998;11:1128–1134.
15.
Reisch S, Daniuk J, Steltner H, Ruhle KH, Timmer J, Guttmann J: Detection of sleep apnea with the forced oscillation technique compared to three standard polysomnographic signals. Respiration 2000;67:518–525.
16.
Michels A, Decoster K, Derde L, Vleurinck C, Van de Woestijne KP: Influence of posture on lung volumes and impedance of respiratory system in healthy smokers and nonsmokers. J Appl Physiol 1991;71:294–299.
17.
Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S: The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med 1993;328:1230–1235.
18.
Vilke GM, Chan TC, Neuman T, Clausen JL: Spirometry in normal subjects in sitting, prone, and supine positions. Respir Care 2000;45:407–410.
19.
Nahmias J, Karetzky MS: Upright and supine flow-volume curves in patients with OSA. N J Med 1989;86:115–119.
20.
Shepard JW Jr, Burger CD: Nasal and oral flow-volume loops in normal subjects and patients with obstructive sleep apnea. Am Rev Respir Dis 1990;142:1288–1293.
21.
Masumi S, Nishigawa K, Williams AJ, Yan-Go FL, Clark GT: Effect of jaw position and posture on forced inspiratory airflow in normal subjects and patients with obstructive sleep apnea. Chest 1996;109:1484–1489.
22.
Lin CC, Wu KM, Choua CS, Liawa CS: Oral airway resistance during wakefulness in eucapnic and hypercapnic sleep apnea syndrome. Respir Physiol Neurobiol 2004;139:215–224.
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2008
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