Assessing Blood Pressure Variability in a Healthy Adult Population During Transcutaneous Hypoglossal Nerve Stimulation With the Zeus Sleep Device

During sleep the upper-airway muscles relax, in obstructive sleep apnoea (OSA) this causes repeated narrowing (hypopnoea) and obstruction (apnoea) (NICE, 2021). These periods of reduced breathing cause arousals fragmenting sleep. Symptoms include snoring, impaired performance, waking headaches, and excessive daytime sleepiness (Arnardottir et al., 2016, Spicuzza et al., 2015). OSA additionally impacts quality of life and cognition (Vaessen et al., 2015) and increases risks of hypertension and cardiovascular morbidity (Peppard et al., 2000, Nieto, 2000, Marin et al., 2012). Diagnosis of OSA uses sleep studies, requiring an apnoea hypopnoea index (AHI) of ≥5/hr (NICE, 2021). Peppard et al. (2013) estimate the prevalence of sleep disordered breathing, of which OSA is the most common, to be 26% of 30-70-year-olds and rising.

The gold standard treatment of OSA is continuous positive airway pressure (CPAP) (NICE, 2021), requiring >4hrs/night usage for effective treatment and risk reduction; however, CPAP is not always well tolerated. A review by Weaver et al. (2008) found CPAP nonadherence rates of 29-83%. Alternative treatments include positional modifiers, mandibular advancement devices, and surgery (NICE, 2021, Spicuzza et al., 2015) whose usage is limited by pathophysiology. Further CPAP alternatives are needed.

Hypoglossal nerve stimulation (HNS) is an emerging OSA therapy which uses electrical stimulation to contract the genioglossus muscle, preventing prolapse and maintaining airway patency (NICE, 2017). Strollo et al. (2014) conducted a prospective, single-group, cohort study where non-CPAP compliant OSA patients had a subcutaneous HNS device implanted. A clinically significant decrease in median AHI of 68% (29.3 to 7.4/hr, P<0.001) was seen 12 months post-implantation alongside improved sleepiness and quality of life. A separate study of 113 participants by Woodson et al. (2025) also showed significant improvements in mean AHI (-18.3 ± 11.8/hour, P<0.001) following HNS implantation. Whilst HNS has shown promising efficacy and acceptable safety profile (NICE, 2017, Strollo et al., 2014, Woodson et al. 2025, Friedman et al. 2016), HNS requires a general anaesthesia and carries all the associated risks and costs of an invasive procedure. Interest has therefore turned to transcutaneous HNS as a non-invasive, cost-efficient alternative.

According to Steier et al. (2011), transcutaneous electrical stimulation (TESLA) of the hypoglossal nerve via bilateral hydrogel patches located in the submental area causes contraction of the genioglossus muscle similarly to subcutaneous HNS. A recent randomised controlled trial in OSA patients by Ratneswaran et al., (2023) compared TESLA to usual care (CPAP). An adjusted reduction in AHI of 7/hr with TESLA was seen at 3 months, however this was not significant (P=0.12) potentially due to small sample size or absent additional interrogation. Indeed, Pengo et al. (2016) indicated that only some participants are responders to TESLA, in their randomised, sham-controlled crossover trial a significant reduction in AHI was only seen in responders (9.1/hr, p=0.004). Meta-analysis by Wang et al. (2025) and Young Jae Byun et al. (2020) both concluded that TESLA results in a meaningful AHI reduction. TESLA appears to be well tolerated by patients with minimal adverse events (Pengo et al., 2016, Ratneswaran et al., 2023, Reed et al., 2016).

Despite the promising research, it is possible that submental electrical stimulation could affect blood pressure due to its proximity to carotid sinus baroreceptors. A similar device to TESLA, TENS machines, are contraindicated for use in the neck region (NHS, 2017). However, a sham-controlled, randomized crossover trial of HNS in 60 participants by Dedhia et al., (2023) concluded there was not a significant difference in mean 24-systolic blood pressure between sham and active groups. Furthermore, a study by Alsharifi et al. (2023) found submental TESLA in 13 healthy participants caused a significant decrease in blood pressure (systolic: p=4.93E-06, diastolic: p=3.48E-09, mean: p=3.88E-08); supported by a meta-analysis that concluded electrical stimulation of the upper airways reduced both systolic and diastolic blood pressure (Khaled et al., 2025). Whilst current evidence indicates that TESLA is unlikely to elicit hypertension, in a patient cohort already at increased risk of hypertension and cardiovascular morbidity, it is vital risk is not compounded by treatment.

This study aims to evaluate the short-term impact of hypoglossal nerve TESLA on blood pressure. We hypothesise that submental TESLA will not increase blood pressure or short-term blood pressure variability and may lead to modest reductions, consistent with previous studies.