Alcohol Alters Sensory Processing to Respiratory Stimuli in Healthy Men and Women During Wakefulness

Study Objectives: Alcohol can cause sleep-disordered breathing in healthy men, increase O-2 desaturation in men who snore, and worsen obstructive sleep apnea (OSA) severity in men with OSA. These findings are less consistent among women, and the underlying mechanisms are incompletely understood. Respiratory-load sensory processing, which underpins upper-airway and respiratory responses to increased breathing load, is potentially impaired by alcohol. Using respiratory-related evoked potentials (RREPs) during wakefulness, this study aimed to test the hypothesis that alcohol impairs respiratory-load sensory processing and to explore potential sex differences. Design: Within-subjects cross-over design in men versus women. Setting: Sleep physiology laboratory. Participants: Twenty healthy individuals (9 women) aged 18 to 38 years. Interventions: Within each subject, RREP waveform components were generated by similar to 60 brief early-inspiratory negative-pressure pulses (-13 cm H2O mask pressure, 200 ms) before and after acute alcohol administration (1.5 mL/kg body weight). Choanal and epiglottic pressures were recorded to monitor stimulus magnitude and upper-airway resistance. Measurements and Results: The latency of several RREP waveform components increased after the administration of alcohol (Delta N1 = 11 +/- 5 ms, Delta N2 = 6 +/- 3 ms, Delta P3 = 26 +/- 10 ms), and P2 amplitude decreased (3.4 +/- 1.5 mu V vs 1.2 +/- 0.8 mu V). There were no changes in P1 latency or amplitude. During relaxed breathing, nasal resistance increased after alcohol ingestion (1.38 +/- 0.16 vs 1.86 +/- 0.18 cm H2O center dot I-1.s(-1)), but pharyngeal and supraglottic resistances remained unchanged. RREP waveform components and upper-airway resistance measures were not different in men versus women before or after alcohol ingestion. Conclusions: These data demonstrate that alcohol alters sensory processing of respiratory neural information, but not early neural transmission (P1), to a similar extent in healthy men and women. Altered sensory processing to respiratory stimuli, as well as nasal congestion, may be important mechanisms contributing to alcohol-related sleep disordered breathing.