Influence of nasal obstruction on obstructive sleep apnea.

Nasal obstruction, either partial or complete, may cause snoring and/or obstructive sleep apnea (OSA). However, there is no clear answer to the question, in how many cases nasal airway is a main or combined site of obstruction. Fifty-four OSA cases (47 men and 7 women) were examined by measuring the upper airway pressure gradient while they were asleep, using a multi-sensor pressure transducer. Their average apnea + hypopnea index was 35.6/h and body mass index was 26.5 kg/m2. Our hypothesis was that elevation of the inspiratory negative airway pressure at the epipharynx could indicate the influence of nasal obstruction. Seven cases out of 54 proved to have inspiratory negative pressure more than -3 cmH2O at the epipharynx during sleep. Four cases indicated elevated negative pressure in the lateral position, and 3 cases out of 19 CPAP candidates showed the same elevation in the supine position. In all 7 cases, the main obstructive site was either at the soft palate or the base of the tongue. Although nasal airway is the preferred route of respiration during sleep, nasal obstruction itself cannot be a main factor causing OSA, but a co-factor of OSA during sleep.