Mj. Brennick et al., MRI STUDY OF REGIONAL VARIATIONS OF PHARYNGEAL WALL COMPLIANCE IN CATS, Journal of applied physiology (1985), 85(5), 1998, pp. 1884-1897
Upper airway compliance indicates the potential of the airway to colla
pse and is relevant to the pathogenesis of obstructive sleep apnea. We
hypothesized that compliance would vary over the rostral-to-caudal ex
tent of the pharyngeal airway. In a paralyzed isolated upper airway pr
eparation in cats, we controlled static upper airway pressure during m
agnetic resonance imaging (MRI, 0.391-mm resolution). We measured cros
s-sectional area and anteroposterior and lateral dimensions from three
-dimensional reconstructed MRIs in axial slices orthogonal to the airw
ay centerline. High-retropalatal (HRP), midretropalatal (MRP), and hyp
opharyngeal (HYP) regions were defined. Regional compliance was signif
icantly increased from rostral to caudal regions as follows: HRP < MRP
< HYP (P < 0.0001), and compliance differences among regions were dir
ectly related to collapsibility. Thus our findings in the isolated upp
er airway of the cat support the hypothesis that regional differences
in pharyngeal compliance exist and suggest that baseline regional vari
ations in compliance and collapsibility may be an important factor in
the pathogenesis and treatment of obstructive sleep apnea.