Transauricular Vagus Nerve Stimulation Frequencies for Postoperative Pain
TVNS-PAIN
Effects of Different Frequencies of Transauricular Vagus Nerve Stimulation on Postoperative Pain: A Randomized, Double-Blind, Sham-Controlled Trial With Preoperative and Postoperative Sessions
1 other identifier
interventional
174
1 country
1
Brief Summary
The goal of this clinical trial is to learn whether different frequencies of transauricular vagus nerve stimulation (tVNS) can reduce postoperative pain and opioid consumption in adults undergoing abdominal or urologic surgery. It will also evaluate the effects of tVNS on recovery quality, autonomic function, and treatment safety. The main questions it aims to answer are: Does transauricular vagus nerve stimulation reduce postoperative opioid consumption during the first 24 hours after surgery? Do different stimulation frequencies (high-frequency and low-frequency tVNS) produce different effects on postoperative pain and autonomic responses? Is transauricular vagus nerve stimulation safe and well tolerated in surgical patients? Researchers will compare high-frequency tVNS, low-frequency tVNS, and sham stimulation (inactive stimulation) to determine their effects on postoperative pain and opioid requirements. Participants will: Be randomly assigned to receive high-frequency tVNS, low-frequency tVNS, or sham stimulation. Receive two 30-minute stimulation sessions, one before anesthesia and one after surgery in the post-anesthesia care unit. Undergo assessments of postoperative pain, opioid consumption, need for rescue analgesics, postoperative nausea and vomiting, heart rate changes, and quality of recovery. Be monitored for adverse events related to the intervention during the study period. A total of 174 participants will be enrolled in this single-center, randomized, double-blind, sham-controlled clinical trial.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P75+ for not_applicable postoperative-pain
Started Jun 2026
Shorter than P25 for not_applicable postoperative-pain
1 active site
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
Study Start
First participant enrolled
June 1, 2026
CompletedFirst Submitted
Initial submission to the registry
June 2, 2026
CompletedFirst Posted
Study publicly available on registry
June 8, 2026
CompletedPrimary Completion
Last participant's last visit for primary outcome
November 30, 2026
ExpectedStudy Completion
Last participant's last visit for all outcomes
December 4, 2026
June 10, 2026
May 1, 2026
6 months
June 2, 2026
June 7, 2026
Conditions
Keywords
Outcome Measures
Primary Outcomes (1)
Total postoperative opioid consumption during the first 24 hours after surgery
Total opioid consumption during the first 24 postoperative hours, recorded according to the institutional postoperative analgesia protocol.
24 hours after surgery
Secondary Outcomes (6)
Postoperative pain intensity (VAS)
Before stimulation in the post-anesthesia care unit, immediately after stimulation, 2 hours after surgery, and 24 hours after surgery
Rescue analgesic use
Within 24 hours after surgery
Postoperative nausea and vomiting (PONV)
Within 24 hours after surgery
Heart rate changes
Immediately before and immediately after each stimulation session (preoperative and postoperative).
Quality of Recovery (QoR-15 Score)
Baseline (preoperative) and 24 hours after surgery.
- +1 more secondary outcomes
Study Arms (3)
High-Frequency tVNS
EXPERIMENTALParticipants will receive active transauricular vagus nerve stimulation (tVNS) at a frequency of 60-120 Hz. Stimulation will be applied bilaterally to the auricular branch of the vagus nerve for 30 minutes before anesthesia and for 30 minutes after surgery. Current intensity will be adjusted between 2 and 6 mA according to participant tolerance.
Low-Frequency tVNS
EXPERIMENTALParticipants will receive active transauricular vagus nerve stimulation (tVNS) at a frequency of 10-20 Hz. Stimulation will be applied bilaterally to the auricular branch of the vagus nerve for 30 minutes before anesthesia and for 30 minutes after surgery. Current intensity will be adjusted between 2 and 6 mA according to participant tolerance.
Sham tVNS
SHAM COMPARATORParticipants will receive sham transauricular vagus nerve stimulation. The device will be positioned and activated to mimic active treatment, but stimulation will be discontinued shortly after initiation. Participants will undergo two 30-minute sessions, one before anesthesia and one after surgery, while maintaining blinding to treatment allocation.
Interventions
Non-invasive electrical stimulation of the auricular branch of the vagus nerve applied bilaterally through ear electrodes. Stimulation is delivered before anesthesia and after surgery using predefined frequency settings.
Sham stimulation delivered using the same device and electrode placement as active stimulation. The device is activated to mimic treatment but does not deliver therapeutic electrical stimulation.
Eligibility Criteria
You may qualify if:
- Adults aged 18 to 59 years.
- Undergoing elective abdominal or urologic surgery.
- American Society of Anesthesiologists (ASA) physical status I-III.
- Able and willing to provide written informed consent.
You may not qualify if:
- History of neurological disorders.
- History of psychiatric disorders.
- Inability to understand study procedures.
- Pregnancy.
- Cognitive impairment.
- Communication difficulties that interfere with study assessments.
- Auricular dermatitis or skin lesions at the stimulation site.
- Pre-existing cardiac arrhythmia.
- Chronic opioid use.
- Implanted electronic medical devices, including pacemakers.
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (1)
Hospital Universitário Professor Edgard Santos, Federal University of Bahia (HUPES-UFBA)
Salvador, Estado de Bahia, 40170-110, Brazil
MeSH Terms
Conditions
Condition Hierarchy (Ancestors)
Study Officials
- PRINCIPAL INVESTIGATOR
Rodrigo M Vieira, MD
Botucatu Medical School, São Paulo State University (UNESP)
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- not applicable
- Allocation
- RANDOMIZED
- Masking
- TRIPLE
- Who Masked
- PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
- Masking Details
- Participants, outcome assessors, and data analysts will remain blinded to treatment allocation throughout the study. The researcher responsible for administering the stimulation will not be blinded because intervention assignment is required for device setup and delivery.
- Purpose
- TREATMENT
- Intervention Model
- PARALLEL
- Sponsor Type
- OTHER
- Responsible Party
- PRINCIPAL INVESTIGATOR
- PI Title
- Researcher, Department of Anesthesiology and Surgery
Study Record Dates
First Submitted
June 2, 2026
First Posted
June 8, 2026
Study Start
June 1, 2026
Primary Completion (Estimated)
November 30, 2026
Study Completion (Estimated)
December 4, 2026
Last Updated
June 10, 2026
Record last verified: 2026-05
Data Sharing
- IPD Sharing
- Will share
- Time Frame
- De-identified individual participant data and supporting study documents will be available beginning 3 months after publication of the primary study results and will remain available indefinitely, with no end date.
- Access Criteria
- De-identified data will be available to qualified researchers who provide a methodologically sound research proposal. Requests should be submitted to the principal investigator. Access will be granted following review and approval of the proposed use and execution of a data-sharing agreement.
De-identified individual participant data underlying the results reported in publications arising from this study will be made available, including demographic characteristics, intervention allocation, primary and secondary outcome measures, and adverse event data. Data will be shared only after removal of all direct identifiers to protect participant confidentiality.