Discriminating the severity of pharyngeal collapsibility in men using anthropometric and polysomnographic indices

Abstract

Study objectives: Although obstructive sleep apnea results from the combination of different pathophysiologic mechanisms, the degree of anatomical compromise remains the main responsible factor. The passive pharyngeal critical closing pressure (Pcrit) is a technique used to assess the collapsibility of the upper airway and is often used as a surrogate measure of this anatomical compromise. Patients with a low Pcrit (ie, less collapsible airway) are potential candidates for non-continuous positive airway pressure therapies. However, Pcrit determination is a technically complex method not available in clinical practice. We hypothesized that the discrimination between low and high Pcrit can be estimated from simple anthropometric and polysomnographic indices.

Methods: Men with and without obstructive sleep apnea underwent Pcrit determination and full polysomnography. Receiver operating characteristics analysis was performed to select the best cutoff of each variable to predict a high Pcrit (Pcrit ≥ 2.5 cmH₂O). Multiple logistic regression analysis was performed to create a clinical score to predict a high Pcrit.

Results: We studied 81 men, 48 ± 13 years of age, with an apnea-hypopnea index of 32 [14-60], range 1-96 events/h), and Pcrit of -0.7 ± 3.1 (range, -9.1 to +7.2 cmH₂O). A high and low Pcrit could be accurately identified by polysomnographic and anthropometric indices. A score to discriminate Pcrit showed good performance (area under the curve = 0.96; 95% confidence interval, 0.91-1.00) and included waist circumference, non-rapid eye movement obstructive apnea index/apnea-hypopnea index, mean obstructive apnea duration, and rapid eye movement apnea-hypopnea index.

Conclusions: A low Pcrit (less collapsible) can be estimated from a simple clinical score. This approach may identify candidates more likely to respond to non-continuous positive airway pressure therapies for obstructive sleep apnea.

Keywords: anthropometry; obstructive sleep apnea; pharyngeal critical closing pressure; polysomnography.

Figure 1. Associations between Pcrit and polysomnographic and anthropometric indices.

AHI = apnea-hypopnea index, NREM = non–rapid eye movement sleep, OA = obstructive apnea, Pcrit = passive pharyngeal critical closing pressure, REM = rapid eye movement sleep.

Figure 2. Pcrit according to NREM-OAI/AHI quartiles. Individual data are shown as hollow circles and median values as solid markers.

AHI = apnea-hypopnea index, NREM = non–rapid eye movement sleep, OAI = obstructive apnea index, Pcrit = passive pharyngeal critical closing pressure.