Abstract
The relative impact of mechanical factors on pharyngeal patency in patients with obstructive sleep apnea is poorly understood. The present study was designed to evaluate parameters of the "tube law" on pharyngeal pressure-flow relationships and ollapsibility in patients with obstructive sleep apnea. We developed a mathematical model that considered the collapsible segment of the pharynx to represent an orifice of varying diameter. The model enabled us to assess the effects of pharyngeal compliance (C), neutral cross-sectional area (Ao), external peripharyngeal pressure (P ex), and the resistance proximal to the site of collapse on flow mechanics and pharyngeal collapsibility [critical pressure (Pcrit)]. All parameters were measured in 15 patients with obstructive sleep apnea under propofol anesthesia, both at rest and during mandibular advancement and electrical stimulation of the genioglossus. The data was used both to confirm the validity of the model and to compare expected and actual relationships between the tube-law parameters and the pharyngeal pressure-flow relationship and collapsibility. We found a close correlation between predicted and measured Pcrit (R = 0.98), including changes observed during pharyngeal manipulations. C and Ao were closely and directly interrelated (R = 0.93) and did not correlate with Pcrit. A significant correlation was found between P ex and Pcrit (R = 0.77; P <0.01). We conclude that the pharynx of patients with obstructive sleep apnea can be modeled as an orifice with varying diameter. Pharyngeal compliance and Ao are closely interrelated. Pharyngeal collapsibility depends primarily on the surrounding pressure.
Original language | English (US) |
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Pages (from-to) | 1037-1044 |
Number of pages | 8 |
Journal | Journal of applied physiology |
Volume | 109 |
Issue number | 4 |
DOIs | |
State | Published - Oct 2010 |
Externally published | Yes |
Keywords
- Pharyngeal compliance
ASJC Scopus subject areas
- Physiology
- Physiology (medical)