Effects of genioglossal response to negative airway pressure on upper airway collapsibility during sleep

Continuous negative airway pressure (CNAP) trials can be used to measure upper airway (UA) collapsibility. This procedure can be accompanied by an increase in UA muscle activity. The purpose of this study was to evaluate the influence of CNAP-induced increase in genioglossal (GG) activity on UA collapsibility in 10 healthy sleeping men. UA collapsibility was measured on two occasions; each recording was preceded by the administration of a placebo or diazepam (0.15 mg/kg) in a randomized double-blind crossover design. In seven subjects, the decrease in mask pressure (P-mask) was associated with an increase in mean GG electromyographic (EMG) activity during the placebo trial, with a significant negative relationship between these two variables. This relationship was still observed with diazepam. In six subjects, the slope of the relationship between mean EMG and P-mask was less negative with diazepam. This was associated with an increase in critical pressure (P-crit). With the placebo, a positive relationship was found between P-crit and the slope of the mean EMG/P-mask relationship. We conclude that P-crit is influenced by the GG response to the decrease in P-mask during CNAP.