Published ahead of print on March 4, 2005, doi:10.1164/rccm.200411-1597OC
© 2005 American Thoracic Society doi: 10.1164/rccm.200411-1597OC
Changes in Upper Airway Size during Tidal Breathing in Children with Obstructive Sleep Apnea SyndromeDivisions of Pulmonary Medicine, Critical Care, the Children's Hospital of Philadelphia; Siemens Medical Solutions USA, Inc.; Department of Mechanical Engineering and Mechanics, Drexel University; and Division of Sleep Medicine, Hospital of the University of Pennsylvania, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania Correspondence and requests for reprints should be addressed to Raanan Arens, M.D., Division of Pulmonary Medicine, The Children's Hospital of Philadelphia, 34th Street and Civic Center Boulevard, Philadelphia, PA 19104-4399. E-mail: arens{at}email.chop.edu We performed respiratory-gated magnetic resonance imaging to evaluate airway dynamics during tidal breathing in 10 children with obstructive sleep apnea syndrome (OSAS; age, 4.3 ± 2.3 years) and 10 matched control subjects (age, 5.0 ± 2.0 years). We hypothesized that respiratory cycle fluctuations in upper airway cross-sectional area would be larger in children with OSAS. Methods: Studies were performed under sedation. Respiratory gating was performed automatically at 10, 30, 50, 70, and 90% of inspiratory and expiratory volume. Airway cross-sectional area was measured at four ascending oropharyngeal levels at each increment of the respiratory cycle. Results: We noted the following in subjects with OSAS compared with control subjects: (1) a smaller upper airway cross-sectional area, particularly during inspiration; (2) airway narrowing occurred during inspiration without evidence of complete airway collapse; (3) airway dilatation occurred during expiration, particularly early in the phase; and (4) magnitude of cross-sectional areas fluctuations during tidal breathing noted in OSAS at levels 1 through 4 were 317, 422, 785, and 922%, compared with 19, 15 17, and 24% in control subjects (p < 0.001, p < 0.005, p < 0.001, and p < 0.001, respectively). Conclusions: Fluctuations in airway area during tidal breathing are significantly greater in subjects with OSAS compared with control subjects. Resistive pressure loading is a probable explanation, although increased airway compliance may be a contributing factor.
Key Words: magnetic resonance imaging (MRI) • respiratory-gated MRI • upper airway This article has been cited by other articles:
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