Hypoglossal nerve stimulation for obstructive sleep apnoea; technique, indication and future prospects Continuous positive airway pressure (CPAP) is the treatment of first choice in patients with moderate to severe obstructive sleep apnoea (OSA); however, 1 in 3 patients does not tolerate CPAP. Upper airway stimulation (UAS) is an alternative for CPAP. This is a new treatment, intended for patients with CPAP intolerance or failure. The muscles responsible for protrusion of the tongue are activated by unilateral stimulation of the hypoglossal nerve, resulting in opening up of the pharynx. Since April 2017, UAS treatment has been reimbursed for a select group of patients by the National Healthcare Institute in the Netherlands, leading to an increase in demand for UAS.