Association between positional changes in laboratory values and severity in subjects with obstructive sleep apnea syndrome

Introduction: The aim of the study was to investigate the association between the difference (defined as the remainder, Rm) in laboratory values determined in the upright and supine positions and the severity of obstructive sleep apnea syndrome (OSAS). Materials and Methods: Thirty-three Japanese male subjects with OSAS (apnea/hypopnea index (AHI: the number of apneas and hypopneas per hour) ≥ 5) underwent cephalometric analysis and measurements of nasal resistance in the upright and supine positions. Several parameters in a dental model and physical features were also analyzed. Results: Significant associations of the logarithmic AHI, with neck depth, Rm for the facial axis, and the minimum airway behind the tongue in the supine position were found in multiple linear regression analysis. Conclusion: Our results suggest that neck depth, Rm for the facial axis and the minimum airway behind the tongue in the supine position may be determinants of the severity of OSAS.