The Effect of Non-Invasive Vagus Nerve Stimulation on Anxiety, Sleep Quality, Pain, Itching, and Autonomic Function in Burn Patients

This study is a randomized controlled experimental study designed to investigate the effects of non-invasive vagus nerve stimulation (nVNS) on anxiety, sleep quality, pain, itching, and autonomic nervous system function in adults with burn injuries.

The study population will consist of patients followed at the Burn Outpatient Clinic of Kartal Dr. Lütfi Kırdar City Hospital in Istanbul, Türkiye. Eligible participants will be adults aged 18 to 65 years who have completed the acute phase of burn injury, whose burn injury occurred between 1 month and 1 year before enrollment, and who have second- or third-degree burns involving 5% to 30% of total body surface area. Participants must also report at least one complaint related to anxiety, sleep quality, pain, or itching and provide written informed consent.

A total of 60 participants are planned to be included. Participants will be randomly assigned in equal numbers to an intervention group or a control group. The intervention group will receive conventional physiotherapy and nVNS. The control group will receive conventional physiotherapy only. Both groups will receive treatment 5 days per week for a total of 10 sessions. Conventional physiotherapy will be planned according to each participant's needs and may include strengthening exercises, stretching exercises, balance exercises, active and passive range-of-motion exercises, and interventions for edema. Each conventional physiotherapy session will last approximately 45 minutes.

In the intervention group, nVNS will be applied using electrodes positioned on the tragus and the anterior and posterior surfaces of the concha of the right and left external ear. Stimulation will be delivered continuously for 20 minutes with a biphasic asymmetric waveform, a pulse duration of 300 microseconds, and a frequency of 25 Hz. The stimulation intensity will be increased in 0.1 mA steps until the sensory threshold is reached. If a participant feels unwell during stimulation, the procedure will be stopped.

Outcome assessments will be performed before treatment and after completion of the 10th session. Anxiety will be assessed using the Beck Anxiety Inventory. Sleep quality will be assessed using the Pittsburgh Sleep Quality Index. Pain will be assessed using a visual analog scale. Itching severity will be assessed using the 12-Item Pruritus Severity Scale. Autonomic nervous system function will be evaluated using heart rate variability measurements recorded with a Polar H10 heart rate sensor and analyzed with Kubios HRV software.