Associations of respiratory mechanic instability with respiratory parameters in pediatric patients with obstructive sleep apnea syndrome

Objectives: This study aimed to identify the effectiveness of respiratory mechanic instability (RMI) in the diagnosis of pediatric obstructive sleep apnea syndrome (OSAS). We sought to evaluate the correlations of RMI with sleep-related parameters and determine the effectiveness of using RMI for diagnosing OSAS in children. Methods: Children who underwent polysomnography (PSG) for various reasons were enrolled in this study. Patients' clinical and PSG data at two university hospitals were reviewed retrospectively. During PSG, RMI parameters were automatically calculated according to the phase relationship between thoracic and abdominal movement signals. Results: Among 263 children who underwent PSG, 183 (70.4%) were diagnosed with OSAS (apnea-hypopnea index [AHI] ≥ 1). RMI parameters were higher in the OSAS group than in the control group. They also tended to increase with disease severity. RMI scores were well correlated with respiratory parameters, showing a stronger correlation in those with moderate or severe OSAS without central apnea. Areas under the receiver operating characteristics curves (AUROCs) of RMI indicators were over 0.65. The percentage of RMI in stage duration showed the highest value of the AUROCs. Conclusion: Paradoxical thoraco-abdominal movement assessed by RMI provides additional information. It may be useful in diagnosing OSAS in children.