Defining of the Relationship Between Lung Volumes, Airway Resistance and the Apnea-Hypopnea Index

Objective: Obstructive Sleep Apnea syndrome (OSAS) is characterized by recurrent complete or partial narrowing of the upper respiratory tract during sleep and frequently a decrease in blood oxygen saturation. Upper respiratory tract gap is determined by the balance between collapsing effect of negative intraluminal pressure during inspiration and upper airway dilator muscle activity. In this study, we aimed to describe the relationship among the lung volumes and airway resistance, which are not thought to be directly taken a part in OSAS pathogenesis, and OSAS cases at different severity. Materials and Methods: Our study has been conducted on 105 cases 26 (24.8%) of which are female and 79 (75.2%) male who were applied polisomnography in the Ministry of Health İstanbul Süreyyapaşa Chest Diseases and Chest Surgery Training and Research Hospital, Chest Disease Clinic between January 2008 and May 2008. Whole body plethysmography was performed to cases which filled patient information form containing identity informations, body mass index (BMI), neck circumference, additional disease situation, smoking anamnesis and Epworth sleepiness scale (ESS). Pulmonary function tests, lung volumes and airway resistances were recorded by looking at the expected % values for age, color and weight. Results: Patients were divided into 4 groups according to apnea-hypopnea index; 25.7% of them were diagnosed with simple snoring, 21.9% mild OSAS, 22.9% moderate OSAS, and 29.5% severe OSAS. The expiratory reserve volume (ERV) in severe OSAS was found lower than the other OSAS groups. No difference was determined in terms of respiratory function tests, airway resistance and lung volumes. While the BMI and neck circumference were high in the severe OSAS group, there was no difference among the groups in the ESS according to the severity of the disease. Conclusion: In conclusion, in our study OSAS severity is not affected by other lung volumes except airway resistance and ERV