Transcutaneous electrical nerve stimulation (TENS) offers a potential novel therapeutic option for patients with obstructive sleep apnoea (OSA), according to results from a phase III study.
TENS machines are more usually used for pain relief, particularly for arthritis and during labour, and this is the first time the technology has been tested for people with OSA.
Researchers from King's College London (KCL) and Guy's & St Thomas' NHS Foundation Trust said TENS could provide cheaper, non-invasive treatment compared with continuous positive airway pressure (CPAP).
The authors of the study, published in eClinical Medicine noted that CPAP, which is recommended as a treatment option by the National Institute for Health and Care Excellence, had a 3-month adherence rate of 75%, which dropped to around 25% after 5 years. Corresponding author Joerg Steier, professor of respiratory and sleep medicine at KCL, and a consultant at Guy's & St Thomas', explained: "Not all patients with obstructive sleep apnoea are able to use CPAP therapy, often because the mask can be uncomfortable and in severe cases can lead to sleep deprivation."
Alternatives to CPAP include mandibular advancement devices, and sometimes surgical options like hypoglossal nerve stimulation (HNS). However, HNS requires a pre-assessment visit, surgical implantation, activation, and follow up appointments, Professor Steier noted.
Instead, the researchers hypothesised that TENS might offer a similar and more cost-effective treatment option, with minimal side effects.
Improved Nocturnal Breathing with Reduced Daytime Sleepiness
Results from the transcutaneous electrical stimulation in sleep apnoea (TESLA) trial showed that patients treated with domiciliary TENS to the submental area during sleep produced improvements in nocturnal breathing as well as significant reductions in daytime exhaustion.
The participants were 56 OSA patients from Guy's & St Thomas' who had documented lack of adherence to CPAP therapy. They were randomly assigned to TESLA (29 patients) or usual care with CPAP (27 patients) for at least 3 months. The TENS machine used was a small, battery-operated device with leads connected to electrodes and the electrical current titrated according to skin sensation.
On follow up, the TENS group had a mean apnoea-hypopnoea-index difference of -11.5 h−1 (95% CI −20.7 to −2.3, p 0.016) compared with the CPAP group. After adjustment for baseline values, the difference remained at -7.0 h−1 (−15.7 to 1.8, p = 0.12) in favour of the intervention.
The light and continuous electric stimulation of the TENS machine was enough to keep the airway open while asleep, allowing easy breathing to continue, and TENS also had favourable impacts on sleepiness and sleep fragmentation, described by the researchers as "clinically meaningful outcomes". Other than minor skin irritation and one participant who developed mild headaches, no side-effects were reported.
TENS Non-invasive, Cheaper, and With Fewer Side Effects
Investigators said their trial suggested that TENS treatment could be considered for patients who do not respond well to CPAP, providing a second line treatment that is cheaper and less time-consuming to roll out than current alternatives. In contrast to HNS, "a TENS machine is non-invasive, has few side effects, and is cheap", Prof Steier said, adding that it would be "interesting to see how the method can be used in clinical practice".
The team now plans a multi-centre trial to prove efficacy of TENS in OSA in different healthcare settings. The Sleep Apnoea Trust Association said in an emailed statement that it hoped to see positive results from these follow-up investigations.
Also commenting to Medscape News UK, Dr Erika Kennington, head of research and innovation for Asthma + Lung UK , which helped fund the investigation, said: "This is a brilliant example of an innovation that repurposes existing technology, and continuing to fund this kind of research into product innovation is vital. We look forward to the results of follow-up trials, with these findings potentially offering thousands of people with sleep apneoa and lung conditions new ways to safely and effectively manage their conditions and, vitally, to improve their quality of life."