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Epiglottis cross-sectional area and oropharyngeal airway length in male and female obstructive sleep apnea patients

Authors Ma MA, Kumar R, Macey PM, Yan-Go FL, Harper RM

Received 27 May 2016

Accepted for publication 30 July 2016

Published 3 October 2016 Volume 2016:8 Pages 297—304


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Professor Steven A Shea

Melinda A Ma,1 Rajesh Kumar,2–4 Paul M Macey,4,5 Frisca L Yan-Go,6 Ronald M Harper,1,4
1Department of Neurobiology, 2Department of Anesthesiology, 3Department of Radiological Sciences, David Geffen School of Medicine, 4Brain Research Institute, 5UCLA School of Nursing, 6Department of Neurology, David Geffen School of
Medicine, University of California at Los Angeles, Los Angeles, CA, USA
Introduction: Obstructive sleep apnea (OSA) is a male-predominant condition, characterized by repeated upper-airway collapse with continued diaphragmatic efforts during sleep, and is accompanied by severe physiological consequences. Multiple morphological aspects, including epiglottis cross-sectional area (CSA) and oropharyngeal airway length (OPAL), can contribute to airway collapsibility in the condition. This study focused on the effects of OSA severity, sex, and race on OPA dimensions.
Materials and methods: Two high-resolution T1-weighted image series were collected from 40 mild-to-severe OSA subjects (age 46.9±9 years, body mass index 30.4±5.4 kg/m2, Apnea–Hypopnea Index score 32.8±22.5, 28 males) and 54 control subjects (47±9 years, 24.7±3.8 kg/m2, 32 males) using a 3 T magnetic resonance-imaging scanner. Caucasian, Asian, African-American, and “other” subjects constituted the study pool. Both image series were realigned and averaged, and reoriented to a common space. CSA and OPAL were measured, normalized for subject height, and compared between sexes and disease-severity levels in OSA and control subjects.
Results: Significantly reduced epiglottis CSA appeared only in severe OSA vs controls (P=0.009). OPAL increased significantly with OSA severity vs controls (mild, P=0.027; moderate, P<0.001; severe, P<0.001). OSA males showed increased CSA and greater OPAL than OSA females, which may underlie the increased proportion of affected males with higher apnea–hypopnea index scores. However, no significant differences appeared between CSA and OPAL measures for male and female controls, suggesting that airway morphology may not be the sole contributor for airway collapse. No ethnic or racial differences appeared for CSA or OPAL measures.
Conclusion: Sex-based reductions in epiglottis CSA and increased OPAL in OSA subjects may enhance airway-collapse vulnerability, more so with greater disease severity, and partially underlie male vs female susceptibility to the sleep disorder.
Keywords: magnetic resonance imaging, apnea–hypopnea index, upper-airway length, gender, race 

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