Acute alcohol intake may be of potential hazard in anaesthesia emergency procedures because of consciousness alterations. Alcohol ingestion alters indeed the functions of upper airway muscles and increases the risk of obstructive sleep apnea. However, no data are available on the effects of alcohol on the swallowing reflex (SR), which is a major protective mechanism against pulmonary inhalation and on upper airway resistances (UAR) following external inspiratory load application. This study was designed to investigate the effects of acute alcohol intake on SR and UAR in healthy volunteers. After informed consent, 8 male volunteers (29 +/- 3 years) were studied in the supine position. The tip of a catheter was placed through the naris at the epipharynx level for injection of 3 series of 2 volumes of distilled water (0.25 and 1 ml respectively). Swallows were identified by a submental electromyogram. SR efficiency was assessed by recording 1) the latency (L) between injection and the first swallow, and 2) the number of swallows (N) elicited by each bolus. The subjects were breathing through a facial mask connected to a pneumotachograph. Supraglottic airway pressures (UAP) were recorded using a small balloon catheter placed at the tip of the epiglottis. UAR were calculated as the ration of UAP (cmH2O) on air-flow (l.s-1) at the airflow's peak. After a control set of measurements (TC), including SR assessment and UAR at rest (UARo) and during application of an external inspiratory resistive load (12 cmH2O.l-1 x s-1) (UARr) to sensitize the experiment, the subjects ingested 1 ml.kg-1 of alcohol as 40 degrees vodka.(ABSTRACT TRUNCATED AT 250 WORDS)