Skip to main content
OpenTrials
Not yet recruiting

NCT Number: NCT07827131

Transcutaneous Auricular Vagus Nerve Stimulation for Reducing Postoperative Hypoxemia

Hypoxemia is a common complication in the post-anesthesia care unit (PACU) and represents one of the most meaningful factors associated with poor patient prognosis. Obese patients have a relatively higher incidence of hypoxemia. This may be partly attributable to their unique physiological characteristics. In addition, surgical trauma triggers a systemic inflammatory response with the release of pro-inflammatory factors such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). These mediators increase pulmonary capillary permeability, induce pulmonary edema, and further impair gas exchange. Surgically-induced stress elevates sympathetic tone and reduces vagal activity, which alters bronchial tone and respiratory rhythm and consequently compromises pulmonary function.Postoperative hypoxemia not only prolongs recovery time and increases the likelihood of ICU admission, but severe episodes may also lead to arrhythmia, myocardial ischemia, long-term cognitive and psychiatric disorders, and even cardiac arrest and death. These outcomes impair postoperative recovery and long-term prognosis, prolong hospital stay, and raise healthcare costs.

Although strategies such as postoperative semi-recumbent positioning and intraoperative protective ventilation have been explored, there are currently no preferred interventions or clear clinical guidelines for the prevention of postoperative hypoxemia.

As a non-invasive technique, transcutaneous auricular vagus nerve stimulation (taVNS) activates the auricular branch of the vagus nerve by stimulating the cymba conchae. Vagal activation suppresses macrophage activity and reduces the release of pro-inflammatory cytokines including TNF-α, IL-1β, IL-6 and IL-18, thereby attenuating pulmonary inflammation and edema and improving oxygenation. Afferent vagal signals project to the nucleus tractus solitarius, modulating the medullary respiratory center, respiratory rate and ventilation efficiency. taVNS is easy to perform, safe, applicable in the perioperative period, and has shown promising effects in regulating inflammatory conditions.

This study aims to investigate whether perioperative taVNS reduces the incidence of hypoxemia in the PACU by attenuating excessive sympathetic activation and mitigating pulmonary and systemic inflammatory responses.

Not yet recruiting

Trial opening soon.

Get Notified

Key information

Conditions

Hypoxemia Hypoxia Pathological Conditions, Signs and Symptoms Signs and Symptoms Signs and Symptoms, Respiratory

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Age ≥18 years; Scheduled for elective bariatric surgery; Classified as American Society of Anesthesiologists (ASA) physical status I to III; Capable of understanding the study procedures and various assessment scales and able to effectively communicate with the researchers; Willing to participate in the study and provide written informed consent.

Exclusion criteria

Patients with severe underlying cardiopulmonary diseases (e.g., acute exacerbation of chronic obstructive pulmonary disease, acute myocardial infarction, NYHA class Ⅳ heart failure); Patients with resting SpO₂ <90% before surgery; Patients with a preoperative heart rate below 50 beats per minute or severe arrhythmia; Patients with lesions of the auricular concha (e.g., inflammation, ulcer, deformity, implant) or vagus nerve dysfunction (e.g., diabetic peripheral neuropathy, vagus nerve injury due to prior neck surgery); Patients with a history of implanted stimulators (e.g., pacemakers, implanted vagus nerve stimulators, deep brain stimulators, spinal cord stimulators), cochlear implants, or metallic implants (excluding dental work); Patients with cognitive dysfunction (MMSE score <20), psychiatric disorders, or unable to cooperate with study procedures; Patients who received vagus nerve stimulation or acupuncture within 1 month before the study; Patients with skin damage or dermatological conditions at the electrical stimulation site; Pregnant or lactating women; Patients requiring emergency surgery; Patients participating in other clinical trials.

Treatment and study plan

Transcutaneous Auricular Vagus Nerve Stimulator

Device

Intervention Timing of Transcutaneous Auricular Vagus Nerve Stimulator: The intervention will begin 30 minutes before anesthesia induction and continue until the end of the surgery, terminating after the removal of the endotracheal tube in the PACU. The stimulation parameters are set as follows: frequency 20 Hz, pulse width 200 μs, 30 seconds on / 30 seconds off, with the current intensity set to the maximum amplitude the patient can tolerate (just below the pain threshold).

Primary outcomes

  1. Incidence of Postoperative Hypoxemia in the PACU

    Time frame: Within 30 minutes in the PACU postoperatively

    Numerous clinical studies and consensus statements define hypoxemia as either peripheral oxygen saturation (SpO₂) less than 90% lasting for more than 10 seconds, or a partial pressure of arterial oxygen to fraction of inspired oxygen (PaO₂/FiO₂) ratio less than 300 mmHg during PACU stay.

Secondary outcomes

  1. Incidence and First Onset Time of Moderate Hypoxemia in the PACU

    Time frame: Within 30 minutes in the PACU postoperatively

    Moderate hypoxemia is defined as SpO₂ less than 85% lasting for more than 10 seconds during PACU stay.The first onset time was defined as the time interval from extubation to the first onset of severe hypoxemia.

  2. Incidence of Airway Rescue

    Time frame: Within 30 minutes in the PACU postoperatively

    Airway rescue was defined as the implementation of non-invasive mask ventilation or re-intubation for respiratory support.

  3. Time to Extubation and PACU Length of Stay

    Time frame: Within 30 minutes in the PACU postoperatively

    The time interval from the end of surgical procedure to tracheal extubation. The time interval from PACU admission to PACU discharge.

  4. Postoperative Respiratory Comfort Score

    Time frame: Within 30 minutes in the PACU postoperatively

    Respiratory comfort was evaluated using a 0-10 numerical rating scale, with higher scores indicating better respiratory comfort and lower scores indicating more severe respiratory discomfort.

  5. Incidence of Cough, Pulmonary Infection and Atelectasis within 24 hours after surgery

    Time frame: Within the first day post-surgery

  6. Postoperative Visual Analogue Scale (VAS) pain score

    Time frame: Within the first day post-surgery

    VAS scores were assessed at two states: resting state and coughing state, with scores ranging from 0 to 10 points.

  7. Total Length of Hospital Stay

    Time frame: Up to 5 weeks postoperatively

    The total length of hospital stay refers to the entire duration of the hospitalization from admission to diacharge

  8. Incidence and Severity of Related Adverse Reactions

    Time frame: Up to 5 weeks postoperatively

    Adverse reactions included ear skin erythema, local pain, dizziness, nausea, and bradycardia (heart rate < 50 beats per minute). The severity of adverse reactions was graded according to the following standards: Grade 1, mild discomfort without the need for clinical intervention; Grade 2, symptoms relieved after symptomatic treatment; Grade 3, severe adverse reactions requiring termination of study intervention and formal clinical treatment.

Sponsors and collaborators

Lead sponsor

Affiliated Hospital of Nantong University

Other

Registry information

Official study title

The Effect of Transcutaneous Auricular Vagus Nerve Stimulation on the Incidence of Postoperative Hypoxemia: A Randomized Controlled Trial

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Sep 18, 2026
Registry last updated
Sep 18, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.