Closed-loop stimulation of hypoglossal nerve in a dog model of upper airway obstruction

Electrical stimulation of upper airway (UAW) muscles has been under investi gation as a treatment method for obstructive sleep apnea (OSA), Particular attention has been given to the electrical activation of the genioglossal m uscle, either directly or via the stimulation of the hypoglossal nerve (NG) , since the genioglossus is the main tongue protrusor muscle. Regardless of the stimulation site or method, an implantable electrical stimulation devi ce for OSA patients will require a reliable method for detection of obstruc tive breaths to apply the stimulation when needed. In this paper, we test t he hypothesis that the activity of the HG nerve can be used as a feedback s ignal for closed-loop stimulation of the HG nerve in an animal model of UAW obstruction where a force is applied on the submental region to physically narrow the airways. As an advantage, the method uses a single electrode fo r both recording and stimulation of the HG nerve. Simple linear filtering t echniques were found to be adequate for producing the trigger signal for th e electrical stimulation from the HG recordings, Esophageal pressure, which was used to estimate the size of the UAW passage, returned to the preloadi ng values during closed-loop stimulation of the HG nerve. The data demonstr ate the feasibility of the closed-loop stimulation of the HG nerve using it s activity as the feedback signal.