Static mechanics of the velopharynx of patients with obstructive sleep apnea.
The static mechanics of the hypotonic pharynx were endoscopically evaluated in nine sleeping patients with obstructive sleep apnea, having a primary narrowing only at the velopharynx. The velopharynx closed completely at a mean pressure of 0.18 +/- 1.21 cmH2O, and the mean half-dilation pressure was 1.93 cmH2O above closing pressure. The dependence of area on pressure was distinctly curvilinear, being steep near closing pressure and asymptotically approaching maximum area (mean = 1.32 cm2). The data for each patient were satisfactorily fitted by an exponential function (mean R2 = 0.98), and a single exponential relationship usefully represented the dependence of relative area on pressure above closing pressure for the population (R2 = 0.85). During the test inspiration, flow limitation was consistently observed when mask pressure exceeded closing pressure by 0.5-3.0 cmH2O. In summary, the static mechanics of the hypotonic velopharynx of patients with obstructive sleep apnea can be described by an exponential pressure-area relationship, with a closing pressure near atmospheric pressure and a high compliance in the range of airway pressure 0-3 cmH2O above closing pressure.
Department of Medicine, Faculty of Medicine, University of Calgary, Alberta, Canada.
S
S
Isono
D L
DL
Morrison
S H
SH
Launois
T R
TR
Feroah
W A
WA
Whitelaw
J E
JE
Remmers
D000328:Adult; D000399:Air Pressure; D003975:Diazepam / Q000494:pharmacology; D004562:Electrocardiography / Q000187:drug effects; D004569:Electroencephalography / Q000187:drug effects; D004576:Electromyography; D004585:Electrooculography / Q000187:drug effects; D005260:Female; D006801:Humans; D008170:Lung Compliance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009960:Oropharynx / Q000503:physiopathology*; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D010160:Palate, Soft / Q000503:physiopathology*; D010609:Pharyngeal Muscles / Q000502:physiology; D011175:Positive-Pressure Respiration; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*
D003975:Diazepam