Simon A Joosten1,2,3, Shane A Landry4,5, Scott A Sands6,7, Philip I Terrill8, Dwayne Mann8, Christopher Andara3, Elizabeth Skuza1, Anthony Turton1, Philip Berger4, Garun S Hamilton1,2,3, Bradley A Edwards4,5. 1. Monash Lung and Sleep, Monash Medical Centre, Clayton, VIC, Australia. 2. School of Clinical Sciences, Monash University, Melbourne, VIC, Australia. 3. Monash Partners - Epworth Sleep Centre, Melbourne, VIC, Australia. 4. Sleep and Circadian Medicine Laboratory, Department of Physiology, Monash University, Melbourne, VIC, Australia. 5. School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Melbourne, VIC, Australia. 6. Department of Allergy, Immunology and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, VIC, Australia. 7. Division of Sleep and Circadian Disorders, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. 8. School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, Qld, Australia.
Abstract
BACKGROUND AND OBJECTIVE: Obstructive sleep apnoea (OSA) is typically worse in the supine versus lateral sleeping position. One potential factor driving this observation is a decrease in lung volume in the supine position which is expected by theory to increase a key OSA pathogenic factor: dynamic ventilatory control instability (i.e. loop gain). We aimed to quantify dynamic loop gain in OSA patients in the lateral and supine positions, and to explore the relationship between change in dynamic loop gain and change in lung volume with position. METHODS: Data from 20 patients enrolled in previous studies on the effect of body position on OSA pathogenesis were retrospectively analysed. Dynamic loop gain was calculated from routinely collected polysomnographic signals using a previously validated mathematical model. Lung volumes were measured in the awake state with a nitrogen washout technique. RESULTS: Dynamic loop gain was significantly higher in the supine than in the lateral position (0.77 ± 0.15 vs 0.68 ± 0.14, P = 0.012). Supine functional residual capacity (FRC) was significantly lower than lateral FRC (81.0 ± 15.4% vs 87.3 ± 18.4% of the seated FRC, P = 0.021). The reduced FRC we observed on moving to the supine position was predicted by theory to increase loop gain by 10.2 (0.6, 17.1)%, a value similar to the observed increase of 8.4 (-1.5, 31.0)%. CONCLUSION: Dynamic loop gain increased by a small but statistically significant amount when moving from the lateral to supine position and this may, in part, contribute to the worsening of OSA in the supine sleeping position.
BACKGROUND AND OBJECTIVE: Obstructive sleep apnoea (OSA) is typically worse in the supine versus lateral sleeping position. One potential factor driving this observation is a decrease in lung volume in the supine position which is expected by theory to increase a key OSA pathogenic factor: dynamic ventilatory control instability (i.e. loop gain). We aimed to quantify dynamic loop gain in OSA patients in the lateral and supine positions, and to explore the relationship between change in dynamic loop gain and change in lung volume with position. METHODS: Data from 20 patients enrolled in previous studies on the effect of body position on OSA pathogenesis were retrospectively analysed. Dynamic loop gain was calculated from routinely collected polysomnographic signals using a previously validated mathematical model. Lung volumes were measured in the awake state with a nitrogen washout technique. RESULTS: Dynamic loop gain was significantly higher in the supine than in the lateral position (0.77 ± 0.15 vs 0.68 ± 0.14, P = 0.012). Supine functional residual capacity (FRC) was significantly lower than lateral FRC (81.0 ± 15.4% vs 87.3 ± 18.4% of the seated FRC, P = 0.021). The reduced FRC we observed on moving to the supine position was predicted by theory to increase loop gain by 10.2 (0.6, 17.1)%, a value similar to the observed increase of 8.4 (-1.5, 31.0)%. CONCLUSION: Dynamic loop gain increased by a small but statistically significant amount when moving from the lateral to supine position and this may, in part, contribute to the worsening of OSA in the supine sleeping position.
Authors: Bradley A Edwards; Andrew Wellman; Scott A Sands; Robert L Owens; Danny J Eckert; David P White; Atul Malhotra Journal: Sleep Date: 2014-07-01 Impact factor: 5.849
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Authors: Simon A Joosten; Bradley A Edwards; Andrew Wellman; Anthony Turton; Elizabeth M Skuza; Philip J Berger; Garun S Hamilton Journal: Sleep Date: 2015-09-01 Impact factor: 5.849
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Authors: Simon A Joosten; Michael Tan; Ai-Ming Wong; Shane A Landry; Paul Leong; Scott A Sands; Caroline Beatty; Luke Thomson; Jeremy Stonehouse; Anthony Turton; Garun S Hamilton; Bradley A Edwards Journal: J Clin Sleep Med Date: 2021-03-01 Impact factor: 4.062