[Electrical stimulation of the genioglossus to improve pharyngeal patency in obstructive sleep apnea: comparison of results obtained during sleep and anesthesia].

Contraction of the geniogtossus (GG) has been shown to improve upper airway patency in patients with sleep apnea during sleep and anesthesia. However, a large variability in response exists, requiring selection of adequate patients if GG stimulation should be used as a treatment modality. In the present study, we compared responses in upper airway pressure-flow relationships to electrical stimulation of the GG in patients with obstructive sleep apnea during sleep and mild anesthesia. Nine patients studied during sleep were matched with 9 patients evaluated during propofol anesthesia. Stimulation was performed with fine wire electrodes inserted near the mandibular insertion of the GG. Airflow was measured at muLtiple levels of CPAP, and upper airway collapsibility was defined by the pressure below which airflow ceased (the "critical" pressure, Pcrit). ELectrical stimulation shifted the pressure-flow reLationships toward higher flow Levels in all patients over the entire range of CPAP applied. Pcrit decreased significantly during stimulation-induced contraction of the GG, and similarly in the patients evaluated during sleep and during anesthesia (from 1.6 +/- 2.0 to -1.6 +/- 2.5, and from 1.8 +/- 1.8 to -0.2 +/- 1.8 cmH2O, during steep and anesthesia, respectively, p < 0.01, without a significant change in upstream resistance. Our findings imply that responses in Pcrit to electrical stimulation of the main tongue protrusor during propofoL anesthesia may reflect those observed during sleep, and evaluation of the response of sleep apnea patients to GG stimulation can be evaluated during short anesthesia.