lung function capacities in obstructive sleep apnea syndrome

Background and objective: 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.materials and methods: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.results: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.conclusion: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.