Randomised, Double-blinded, Sham-controlled Cross-over Trial of Continuous Transcutaneous Electrical Stimulation of the Pharyngeal Dilator Muscles in Obstructive Sleep Apnoea

Obstructive sleep apnoea is the most common problem of sleep-disordered breathing. It affects at least four percent of the male and two percent of the female adult population. It is associated with excessive daytime sleepiness, causing significant disturbance of daytime routines affecting work, social life and memory; untreated, it also causes a significant cardiovascular and metabolic risk. The best available treatment for obstructive sleep apnoea is continuous positive airway pressure (CPAP). However, not everyone eligible tolerates this treatment because it requires them to sleep with a nasal or full-face mask that is connected by a tube to a machine. Although CPAP is recommended by the National Institute for Health and Clinical Excellence (NICE) for moderate-severe sleep apnoea, approximately one third of sleep apnoea patients who should be on CPAP stop therapy within five years. Mild sleep apnoea is currently treated with mandibular advancement splints and generic sleep hygiene advice.

Continuous transcutaneous electrical stimulation (CTES) of the submental region activates the muscles that dilate the upper airway. This is where airway obstruction occurs in sleep apnoea. It has been shown that CTES at night for short periods (10minutes) effectively stimulates the genioglossus muscle, the strongest pharyngeal dilator and reduces upper airway obstruction, work of breathing and neural respiratory drive in patients with sleep apnoea. The London Respiratory Muscle Groups, based within King's Health Partners and the Royal Brompton Hospital, has developed a CTES stimulator device. This device senses apnoeas and snoring and delivers CTES until normal ventilation has been restored.

We propose to undertake a randomized, double-blinded, sham-controlled cross-over trial with sleep apnoea patients to evaluate the efficacy of this method. Patients will be randomly assigned to a night of CTES or sham-stimulation. The primary outcome measure is the number of oxygen desaturations per hour (ODI) caused by apnoeas and the secondary outcome measures are sleepiness, as measured by the Epworth sleepiness score, the apnoea-hypopnoea-index (AHI) and comfort, as assessed by a visual analogue score. The sample size Calculation using data from our own published pilot study revealed that this study would require 44 patients to be enroled. The mean study duration until all outcomes will be assessed for each patient will be four weeks. We plan to commence the study in winter 2012/13 for a period of two years, including analysis and publication, to be concluded in December 2014.