Nasal resistance in snorers with or without sleep apnea: effect of posture and nasal ventilation with continuous positive airway pressure.

We investigated the effects of posture and nasal ventilation with continuous airway pressure (CPAP) on nasal resistance in snorers with or without obstructive sleep apnea (OSA). Posterior rhinomanometry was performed in 70 snorers referred for polysomnography and in 11 nonsnoring volunteers, (1) in the seated posture; (2) and (3) after 10 minutes in the supine position, before and after inhalation of oxymetazoline; and (4) 10 minutes after return to the seated position. The effect of CPAP on posterior rhinomanometry was also examined in the nonsnorers and in 12 of the snorers. Changing from the seated to the supine position resulted in an increase in resistance in snorers and nonsnorers (resistance supine 182 +/- 10.9% and 128 +/- 6.7% respectively of seated value, p < 0.05). After oxymetazoline instillation, resistance in the supine position decreased but remained higher in snorers than baseline value in the seated position. Effects of posture and oxymetazoline were similar in snorers with or without sleep apnea. During nasal ventilation with CPAP, resistance was 30 +/- 3.8 and 45 +/- 4.4% of value before CPAP in snorers and nonsnorers, respectively (p < 0.05). These effects of posture and CPAP were also observed when resistance was measured with anterior rhinomanometry. In conclusion, nasal resistance measured with posterior rhinomanometry in the supine position is not predictive for OSA. Nasal ventilation with CPAP resulted in an acute and marked decrease in nasal resistance.