The effect of electrical stimulation of the upper airway dilator muscles on blood pressure in healthy volunteers and patients with obstructive sleep apnoea: a systematic review and meta-analysis

Background Long-term adherence to continuous positive airway pressure (CPAP), the standard treatment for obstructive sleep apnoea (OSA), is often poor. Electrical stimulation of upper airway dilator muscles through hypoglossal nerve stimulation (HNS) has emerged as an effective non-CPAP alternative. However, evidence regarding its effect on the cardiovascular system remains limited. Methods A meta-analysis investigating the effect of HNS and transcutaneous electrical nerve stimulation (TENS) on blood pressure was conducted (PROSPERO: CRD42023429546). MEDLINE/PubMed and Web of Science Core Collection databases were searched up to 25th January 2024. Quality assessment was performed using the Cochrane risk-of-bias for randomised trials tool and Newcastle-Ottawa Scale for non-randomised studies. Results Of 6260 eligible studies identified, eight underwent full-text screening. Four did not measure change in blood pressure and were excluded. Data from the remaining four studies (n=304) were pooled (three HNS studies (n=291) and one TENS study (n=13)). Patients were middle-aged (59.3 (13.1) years), overweight (body mass index, 28.7 (3.8) kg×m −2 ), and had moderate-to-severe OSA (apnoea-hypopnoea index, 34.8 (7.1)×hour −1 ). Electrical stimulation was associated with a trend towards reduction in systolic (−3.44 (CI −7.98 to 1.10) mm Hg), diastolic (−3.41 (CI −8.10 to 1.27) mm Hg), and mean arterial blood pressure (−5.69 (CI −13.66 to 2.28) mm Hg). Conclusion A trend between electrical stimulation of upper airway dilator muscles and reduction in blood pressure was demonstrated. Further studies on normal subjects and patients with OSA are required to compare the effects on blood pressure to CPAP.