Lung Function Capacities in Obstructive Sleep Apnea Syndrome

Previous studies have reported abnormal changes in spirometric parameters and flow-volume curves in patients with obstructive sleep apnea syndrome (OSAS) during sleep. This study aimed to evaluate the lung function capacities and flow-volume curves in these patients.
This was a cross-sectional study. A total of 120 adults aged 18-65 years with suspected OSAS were selected. A full record of demographic characteristics and history of chronic diseases, as well as the results of spirometry and polysomnography were obtained. Spirometric indices and flow-volume curves in OSAS patients and normal subjects were compared.
The mean body mass index was 30.85 ± 6.18 kg/m2. Average neck and abdominal circumferences were 41.68 ± 3.53 and 108.56 ± 14.34 (cm); respectively. The subjects were divided into three groups based on their AHI. The sawtooth signal was observed in a flow-volume curve in 20.2% and 2.8% of patients with and without OSAS; respectively. Significant differences were seen in sawtooth appearance signs and forced expiratory flow (FEF) 50/forced inspiratory flow (FIF) 50 (P > 0.001), but these parameters were not significantly different in AHI subgroups of sleep apnea.
Sawtooth sign and FEF50/FIF50 ≥ 1 could be useful in diagnosis of OSAS, although it cannot be used to predict the severity. Despite a significant difference in a sawtooth sign and FEF50/FIF50 between OSAS patients and nor-mal subjects, no significant differences in lung functions were observed between OSAS patients and normal subjects.