Increases in airflow adequate to eliminate inhibitory airflow limitation in most patients
THURSDAY, Dec. 1 (HealthDay News) -- For patients with obstructive sleep apnea (OSA), hypoglossal nerve simulation (HGNS) produces marked dose-related increases in airflow, without arousing patients from sleep, according to a study published online Nov. 25 in the American Journal of Respiratory and Critical Care Medicine.
Alan R. Schwartz, M.D., from Johns Hopkins School of Medicine in Baltimore, and colleagues investigated the effect of graded increases in HGNS on pharyngeal obstruction during sleep in 30 patients with OSA who were implanted with an HGNS system. During non-REM sleep, the current (mA) was increased in a stepwise manner at fixed frequency and pulse width. Stimulation was applied on alternate breaths at each current level, and responses in the maximal inhibitory airflow (V1max) and inhibitory airflow limitation (IFL) were measured. The current levels at which V1max first increased and peaked (flow capture and peak flow thresholds), or increased from flow capture to peak, were used to characterize the pharyngeal responses to HGNS.
The investigators found that with the current increasing from 1.05 ± 0.09 to 1.46 ± 0.11 mA, HGNS produced linear increases in V1max from unstimulated levels at flow capture to peak flow thresholds (215 ± 21 to 509 ± 37 mL/s). All patients showed an increase in V1max and in 57 percent of patients, IFL was eliminated (non-IFL subgroup). The non-IFL subgroup had a significantly greater flow response slope (1,241 ± 199 versus 674 ± 166 mL/s/mA), and a significantly lower stimulation amplitude at peak flow (1.23 ± 0.10 versus 1.80 ± 0.20 mA) than the IFL subgroup, with no differences in peak flow.
"HGNS produced marked dose-related increases in airflow without arousing patients from sleep," the authors write.
All of the study authors disclosed financial ties to Apnex Medical Inc., which funded the study and manufactures the HGNS system.
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