Domiciliary use of transcutaneous electrical stimulation for patients with obstructive sleep apnoea: a conceptual framework for the TESLA home programme

Abstract

Obstructive sleep apnoea (OSA) is a global health problem of increasing prevalence. Effective treatments are available with continuous positive airway pressure (CPAP) therapy and mandibular advancement devices (MAD). However, there is limited long-term adherence to therapy, as CPAP and MAD require permanent usage to avoid recurrence of the symptoms and adverse ill health. Alternative treatments would aid in the treatment cascade to manage OSA effectively whenever standard therapy has been trialled and failed. Hypoglossal nerve stimulation (HNS), an invasive approach to stimulate the pharyngeal dilator muscles of the upper airway during sleep, has been approved for the treatment of OSA by several healthcare systems in recent years. In parallel to the development of HNS, a non-invasive approach has been developed to deliver electrical stimulation. Transcutaneous electrical stimulation in obstructive sleep apnoea (TESLA) uses non-invasive electrical stimulation to increase neuromuscular tone of the upper airway dilator muscles of patients with OSA during sleep. Data from previous feasibility studies and randomised controlled trials have helped to identify a subgroup of patients who are "responders" to this treatment. However, further investigations are required to assess usability, functionality and task accomplishment of this novel treatment. Consideration of these factors in the study design of future clinical trials will strengthen research methodology and protocols, improve patient related outcome measures and assessments, to optimise this emerging therapeutical option. In this review, we will introduce a conceptual framework for the TESLA home programme highlighting qualitative aspects and outcomes.

Keywords: Hypoglossal nerve stimulation (HNS); compliance; continuous positive airway pressure (CPAP); neural stimulation; sleepiness.

Figure 1

Schematic proposal of a conceptual framework TESLA. A: refers to “usability” to reflect the interaction between patient and device; B: refers to “functionality” to describe the link between device and task; C: refers to “task accomplishment” to assess the link between patient and task.

Figure 2

Picture of one of the prototypes of the TESLA programme attached to the submental area.

Figure 3

Ultrasound images of the genioglossus muscle, (A) it shows the relaxed muscle (without stimulation) in a coronal view, (B) it shows the muscle during electrical stimulation and the resulting change in the diameter caused by contraction. As the muscle contracts, it shortens, pulling the pharyngeal wall towards the anterior direction. An increase in the radius by +10% results in an approximate increase in the cross-sectional area (CSA) of the muscle of +21%, assuming a round model (CSA= π × r²).

Figure 4

Endoscopic images of the upper airway. The left panels show the upper airway with the vocal cords and the epiglottis while electrical stimulation is turned “off”, the right panel shows the same area when stimulation is turned “on”. The anterior-posterior diameter increases with stimulation, the tonsilla lingualis becomes visible just underneath the epiglottis when electrical stimulation is turned on (right lower panel).