Upper airways resistance and snoring in anaesthetized dogs.

We have measured upper airways resistance from the trachea and from the pharynx to the atmosphere, EMG of genioglossus muscle, and the sound of snoring, in anaesthetized greyhounds breathing spontaneously through the upper airways. Using extra-corporeally produced continuous flow we determined flow/pressure curves for the upper airways in an expiratory direction and analysed them in terms of resistances from the trachea and from the pharynx. Resistances and other variables were determined with the nose open and the nostrils blocked. About one-third of the dogs snored spontaneously and most of the remainder did so when the nose was blocked. During snoring with nasal blockage the upper airways resistance increased considerably, and the sound of snoring and genioglossus EMG were also enhanced. The results show that the anaesthetized greyhound is a suitable model for studying snoring with simultaneous measurements of upper airways resistance and the activity of pharyngeal dilator muscles.