Premium
Evaluation of the role of lung volume and airway size and shape in supine‐predominant obstructive sleep apnoea patients
Author(s) -
Joosten Simon A.,
Sands Scott A.,
Edwards Bradley A.,
Hamza Kais,
Turton Anthony,
Lau Kenneth K.,
Crossett Marcus,
Berger Philip J.,
Hamilton Garun S.
Publication year - 2015
Publication title -
respirology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 85
eISSN - 1440-1843
pISSN - 1323-7799
DOI - 10.1111/resp.12549
Subject(s) - supine position , medicine , airway , functional residual capacity , anesthesia , lung volumes , cardiology , lung
Background and objective This study aimed to evaluate the involvement of airway cross‐sectional area and shape, and functional residual capacity ( FRC ), in the genesis of obstructive sleep apnoea ( OSA ) in patients with supine‐predominant OSA . Methods Three groups were recruited: (i) supine OSA , defined as a supine apnoea–hyponoea index ( AHI ) at least twice that of the non‐supine AHI ; (ii) rapid eye movement ( REM ) OSA , defined as REM AHI at least twice the non‐ REM AHI and also selected to have supine AHI less than twice that of the non‐supine AHI (i.e. to be non‐positional); and (iii) no OSA , defined as an AHI less than five events per hour. The groups were matched for age, gender and body mass index. Patients underwent four‐dimensional computed tomography scanning of the upper airway in the supine and lateral decubitus positions. FRC was measured in the seated, supine and lateral decubitus positions. Results Patients with supine OSA demonstrated a significant decrease in FRC of 340 mL ( P = 0.026) when moving from the lateral to supine position compared to controls with no OSA , and REM OSA patients. We found no differences between groups in upper airway size and shape. However, all groups showed a significant change in airway shape with the velopharyngeal airway adopting a more elliptoid shape (with the long axis laterally oriented), with reduced anteroposterior diameter in the supine position. Conclusions A fall in FRC when moving lateral to supine in supine OSA patients may be an important triggering factor in the generation of OSA in this patient group.