Effect of Transcutaneous Auricular Vagus Nerve Stimulation on Perioperative Negative Emotions in Breast Cancer Surgery Patients

Patients undergoing breast cancer surgery frequently experience perioperative anxiety and depression, which can adversely affect recovery and quality of life. This study evaluates the efficacy of a single 30-minute intraoperative taVNS session in mitigating these negative emotions and improving postoperative outcomes. Patients will be randomized to receive either active taVNS or sham stimulation after anesthesia induction. The primary outcome is the incidence of depressive symptoms within 3 days postoperatively. Secondary outcomes include anxiety, pain, PONV, sleep quality, and recovery parameters.

• Active taVNS (Device): Stimulation parameters: Amplitude 20 (mA), Frequency 20Hz, Pulse width 200μs, asymmetric biphasic square wave. A single 30-minute stimulation session is applied to the left auricular concha after anesthesia induction.
• Sham taVNS (Device): The sham device is identical in appearance, weight, indicator lights, and operation sounds to the active device but delivers no effective electrical current. It is applied to the left auricular concha for 30 minutes after anesthesia induction.

Primary outcomes

• Incidence of Postoperative Depressive Symptoms [Within 3 days after surgery]: Assessed using the Patient Health Questionnaire-9 (PHQ-9), Hamilton Depression Rating Scale (HAMD-17), and the depression subscale of the Hospital Anxiety and Depression Scale (HADS-D). A score above the standard cut-off on any of these scales indicates the presence of depressive symptoms.

Secondary outcomes

• Incidence of Postoperative Anxiety Symptoms [Within 3 days, 7 days, and at 30 days after surgery]: Assessed using the anxiety subscale of the Hospital Anxiety and Depression Scale (HADS-A), the Generalized Anxiety Disorder-7 (GAD-7), and the Self-Rating Anxiety Scale (SAS).
• Incidence of Depressive Symptoms [Postoperative day 7 and 30]: Assessed using the Patient Health Questionnaire-9 (PHQ-9), Hamilton Depression Rating Scale (HAMD-17), and the depression subscale of the Hospital Anxiety and Depression Scale (HADS-D). A score above the standard cut-off on any of these scales indicates the presence of depressive symptoms.Higher scores indicate greater severity of depression.
• Postoperative Nausea and Vomiting (PONV) [Within 3 days after surgery]: Assessed using a Visual Analogue Scale (VAS, 0-10)
• Postoperative Pain Score [Postoperative day 3, 7, and 30]: Assessed using the Numerical Rating Scale (NRS, 0-10).
• Postoperative Sleep Quality [Postoperative day 3, 7, and 30]: Assessed using the Insomnia Severity Index (ISI, score 0-28).
• Time to First Postoperative Flatus and Defecation [From end of surgery until first occurrence, assessed up to 7 days]: Time to First Postoperative Flatus and Defecation
• Postoperative Recovery Quality [Postoperative day 3, 7, and 30]: Assessed using the Quality of Recovery-15 or QoR-40 scale.
• Postoperative Quality of Life [Postoperative day 3, 7, and 30]: Assessed using the EQ-5D-5L scale.

Other outcomes

• Length of Hospital Stay [From admission day (Day 0) to discharge day (the time range for calculating Length of Hospital Stay is from the admission day to the discharge day)]: Length of Hospital Stay
• Postoperative Complications [From surgery completion to hospital discharge or up to 30 days postoperatively]: Incidence of complications such as respiratory failure, stroke, acute kidney injury, etc.
• CRP [Preoperative day, end of surgery, postoperative day 1]: Perioperative Serum Biomarker: C-Reactive Protein (CRP) Levels
• IL-6 [Preoperative day, end of surgery, postoperative day 1]: Perioperative Serum Biomarker: Interleukin-6 (IL-6) Levels
• S100β [Preoperative day, end of surgery, postoperative day 1]: Perioperative Serum Biomarker: S100β Protein Levels
• BDNF [Preoperative day, end of surgery, postoperative day 1]: Perioperative Serum Biomarker: Brain-Derived Neurotrophic Factor (BDNF) Levels
• IL-10 [Preoperative day, end of surgery, postoperative day 1]: Perioperative Inflammatory Cytokine: Interleukin-10 (IL-10) Levels
• Adverse Events Related to taVNS [From stimulation start to postoperative day 3]: Adverse Events Related to taVNS
• Postoperative Mortality [7 days and 30 days after surgery]: Postoperative Mortality
• Arterial Blood Pressure [Perioperative period]: Perioperative Arterial Blood Pressure
• Perioperative Electroencephalogram (EEG) Data [Intraoperative period]: Including Ai (0-100), EMG index, BSR, SEF95, α/β/γ band power.
• Heart Rate [Perioperative period]: Perioperative Heart Rate

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Aged ≥18 years. Scheduled for elective breast cancer surgery. ASA physical status I-III. Willing and able to provide informed consent.

Exclusion Criteria:

* Preoperative MMSE score < 24; severe communication barriers. History of diagnosed dementia, Parkinson's disease, schizophrenia, bipolar disorder, major depressive disorder, or long-term use of psychotropic drugs.

Skin lesions, infection, or deformity of bilateral ears; history of ear surgery or nerve injury; allergy to electrode materials.

Severe arrhythmia; implanted electronic devices (e.g., pacemaker, ICD). Participation in another interventional trial within 3 months. Other conditions deemed unsuitable by investigators.