Effects of Ultrasound-Guided Stellate Ganglion Block and Transcutaneous Auricular Vagus Nerve Stimulation on Sleep Quality After Radical Mastectomy for Breast Cancer

Before the induction of anesthesia in the operating room, a skilled anesthesiologist performed a SGB under sterile conditions using real-time ultrasound in a blind grouping manner. The patient was positioned supine with the neck slightly rotated to the left. A linear probe (6-13 MHz) was placed on the neck to clearly visualize the carotid artery, internal jugular vein, vertebral artery, vagus nerve, thyroid gland, esophagus, scalene muscles, and the anterior scalene muscle at the C6 level. Subsequently, a 48mm, 20-gauge needle was inserted in a "plane" direction into the prevertebral fascia of the anterior scalene muscle. After the needle tip penetrated the prevertebral fascia and negative pressure aspiration was confirmed, 3ml of 0.5% ropivacaine was injected, and the diffusion of the local anesthetic was observed under ultrasound guidance.

Three stimulations of transcutaneous auricular vagus nerve stimulation (taVNS) were administered to the patients: ① According to the manufacturer's recommendations and previous studies [32], the initial adjustment required electrical stimulation to penetrate the skin barrier. The first intervention was conducted one day prior to the surgery, with an initial electrical stimulation frequency set at 30 Hz and a pulse width of 300 μs. The frequency and pulse width were adjusted based on the individual patient's sensations until the maximum tolerable current stimulation was reached without discomfort, lasting for 30 minutes; ② The second intervention occurred immediately after the patient was connected to the monitoring equipment in the operating room, once their vital signs were confirmed to be within normal ranges. The same stimulation frequency as the first intervention was applied for 30 minutes; ③ The third intervention was administered in the recovery room after the patient's surgery