Staging of heavy snorers' disease. A proposal

The passage from trivial snoring to heavy snorer's disease or obstructive apnea syndrome is a subtle and gradual process. The suspect clinical signs of this process are primarily the onset of intermittent snoring and daytime sleepiness. We propose a diagnostic assessment based on objective monitoring of respiratory behaviour (noise of snoring, endothoracic pressure, SaO2) during sleep and the tendency to daytime drowsiness (by means of the so-called multiple sleep latency test, MSLT). These parameters establish not only the presence of a disease state, but also give a fairly accurate indication of the different stages of the disease. The nocturnal respiratory pattern emerging from this objective assessment can be divided into four stages: stage 0 (or preclinical), with sporadic obstructive apneas; stage I (or initial), with obstructive apneas persisting during light (st. 1-2) and REM sleep; stage II (or overt), with obstructive apneas persisting for the whole length of sleep; stage III (or complicated), with alveolar hypoventilation persisting during wakefulness. In stage 0, episodes of O2 desaturation are sporadically present and linked to obstructive apneas or hypopneas. In stages I-II, phasic desaturations are correlated with the apneas. In stage II and above all stage III, phasic desaturation is associated with persistent falls of Sao2.(ABSTRACT TRUNCATED AT 250 WORDS)