Influence of gas density on simulated snoring

According to a recent theoretical model, snoring is related to instability of the upper airway (UA). Factors promoting UA instability include increase d gas density. The aim of this study was to test the influence of gas densi ty on simulated snoring production and supraglottic resistance. Supraglottic pressure and flow rate (V ') were measured in 10 healthy seate d subjects during simulated snoring. Subjects breathed three different gas mixtures: Helium-oxygen, He 79%-O-2 21% (He-O-2); air; and sulphur hexafluo ride-oxygen, F6S 79%-02 21% (F6S-O-2) administered in a random order. Supra glottic resistance (Rsp) was measured on its linear range during quiet brea thing and V ' was measured at the onset and middle of snoring. Linear Rsg increased and V ' conversely decreased with gas density. These d ata are in agreement with predictions of a mathematical model of the upper airway showing that snoring occurs at lower flow rates when gas density is increased.