Influences of nasal continuous positive airway pressure on the upper airway in obstructive sleep apnea patients
Date Issued
2009
Date
2009
Author(s)
Yu, Chia-Ling
Abstract
ObjectivesThe narrowing of the upper airway caliber during sleep is believed to be essential to the pathogenesis of obstructive sleep apnea syndrome (OSAS). Nasal continuous positive airways pressure (nCPAP) is the therapy of choice especially for treating severe OSAS patients. We hypothesized that after continuous using of nCPAP, it could yield some persist changes of the upper airway. The aim of this study was to evaluate the changes of upper airway and its surrounding soft tissues of severe OSAS patients before and after nCPAP therapy.aterial and method 6 severe OSAS patients were randomly assigned into two groups. In experimental group the patients have received nCPAP treatment with optimal pressure, i.e. effective nCPAP; and nCPAP with sub-therapeutic pressure, i.e. sham nCPAP, in control group. Static and dynamic MRI were used to image the upper airways in awakening supine posture of all subjects at baseline and 3 months after nCPAP therapy. The volume of the upper airway and the lateral pharyngeal wall were measured by using the serial static MRI. The area changes of the upper airway caliber sectioned at retro-palatal and retro-glossal levels were obtained from dynamic MRI to represent the collapsibility of the upper airway. The possible persist effects of nCPAP therapy on the upper airway were then analyzed by using these measurements.esults5 subjects in the experimental group and 27 subjects in the control group have completed all the measurements. The total and retro-palatal upper airway volume were significantly increased after using effective nCPAP, but not occurred in controls. The retro-palatal upper airway volume was also correlated with the optimal pressure of the nCPAP (r=0.314, p<0.05). The volume of the lateral pharyngeal wall was significantly correlated with neck circumference (r=0.456) and BMI (0.590); and the lateral pharyngeal volume seemed not to be changed after both effective and sham nCPAP treatments. By comparing the maximal, minimal, and mean area of the upper airway caliber, effective nCPAP treatment didn’t yield collapsibility change in the retro-palatal level but in the retro-glossal level. The collapsibility of the airway both in the retro-palatal and retro-glossal levels were significantly correlated with the optimal pressure of the nCPAP. onclusionn severe OSAS patients, the upper airway volume but not the lateral pharyngeal volume was increased after 3 months of effective nCPAP treatments. It seemed to indicate that such improvement might be due to strengthening of the tissue tone. The collapsibility of the upper airway in the retro-glossal level seemed to be also improved, but our study is not able to provide explanations. The upper airway resistance seemed to be correlated with the ratio between minimal and mean upper airway caliber. Its clinical implication needs future studies.
Subjects
OSAS
MRI
nCPAP
upper airway volume
upper airway collapisibity
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