Postoperative PainTVNS-PAINNCT07633444
Transauricular Vagus Nerve Stimulation Frequencies for Postoperative Pain
A study testing Transauricular Vagus Nerve Stimulation (tVNS) in people with Postoperative Pain and Postoperative Nausea and Vomiting (PONV), run by Federal University of Bahia at 1 site in Brazil.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 59 years
- Conditions the study is for
- Postoperative Pain, Postoperative Nausea and Vomiting (PONV), Opioid Consumption, Postoperative
- What is being tested?
- Transauricular Vagus Nerve Stimulation (tVNS)
- Type of treatment
- Medical device
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 174 participants
- Where
- 1 siteBrazil
- Study dates
- 1 Jun 2026to 4 Dec 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 59 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- 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.
Who cannot join
- History of neurological disorders.
- History of psychiatric disorders.
- Inability to understand study procedures.
- Pregnancy.
- Cognitive impairment.
- Communication difficulties that interfere with study assessments.
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- Auricular dermatitis or skin lesions at the stimulation site.
- Pre-existing cardiac arrhythmia.
- Chronic opioid use.
- Implanted electronic medical devices, including pacemakers.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Brazil1 site, 1 recruiting
- Recruiting
Hospital Universitário Professor Edgard Santos, Federal University of Bahia (HUPES-UFBA)
Salvador, Estado de Bahia, 40170-110
João Paulo A Carvalho, 75982953834, joaoaureliano@ufba.br
About this study
Official title: Effects of Different Frequencies of Transauricular Vagus Nerve Stimulation on Postoperative Pain: A Randomized, Double-Blind, Sham-Controlled Trial With Preoperative and Postoperative Sessions
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?
Read more
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.
Read the detailed description
Postoperative pain remains a major challenge in perioperative care and is associated with delayed recovery, increased healthcare utilization, and greater opioid consumption. Despite advances in multimodal analgesia, opioid medications continue to play a central role in postoperative pain management and may be associated with adverse effects such as nausea, vomiting, respiratory depression, and prolonged recovery. Therefore, the development of effective non-pharmacological adjunctive strategies is of considerable clinical interest.
Transauricular vagus nerve stimulation (tVNS) is a non-invasive neuromodulation technique that stimulates the auricular branch of the vagus nerve through the external ear. Experimental and clinical studies suggest that vagal stimulation may modulate pain perception through activation of central autonomic pathways, enhancement of descending inhibitory pain mechanisms, and regulation of inflammatory responses. Previous clinical trials have demonstrated promising effects of tVNS on acute and chronic pain conditions, including reductions in postoperative pain scores.
However, the optimal stimulation parameters for perioperative analgesia remain uncertain. In particular, the influence of stimulation frequency on clinical outcomes and autonomic responses has not been adequately investigated. Different stimulation frequencies may activate distinct neural pathways and produce different effects on pain modulation and autonomic regulation.
This study is designed to evaluate the effects of different frequencies of transauricular vagus nerve stimulation applied before and after surgery in adult patients undergoing elective surgical procedures. In addition to assessing postoperative opioid requirements, the study will explore the relationship between autonomic responses and postoperative recovery. The findings may contribute to the optimization of non-pharmacological analgesic strategies and support the incorporation of transauricular vagus nerve stimulation into multimodal perioperative pain management protocols.
- Conditions
- Postoperative Pain, Postoperative Nausea and Vomiting (PONV), Opioid Consumption, Postoperative
- Being tested
- Transauricular Vagus Nerve Stimulation (tVNS), Sham Transauricular Vagus Nerve Stimulation (sham tVNS)
- Keywords
- Postoperative Pain, Transauricular Vagus Nerve Stimulation, tVNS, Neuromodulation, Opioid Consumption, Pain Management, Randomized Controlled Trial
- Medical subject headings
- Pain, Postoperative, Postoperative Nausea and Vomiting, Agnosia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Transauricular Vagus Nerve Stimulation (tVNS)Device
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 Transauricular Vagus Nerve Stimulation (sham tVNS)Device
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.
| Study group | Role | What they receive |
|---|---|---|
| High-Frequency tVNS | Experimental | Participants 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. Receives: Device: Transauricular Vagus Nerve Stimulation (tVNS) |
| Low-Frequency tVNS | Experimental | Participants 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. Receives: Device: Transauricular Vagus Nerve Stimulation (tVNS) |
| Sham tVNS | Sham comparator | Participants 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. Receives: Device: Sham Transauricular Vagus Nerve Stimulation (sham tVNS) |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 24 hours after surgery
Secondary outcomes (6)
Postoperative pain intensity (VAS)
Pain intensity measured using a 100-mm Visual Analog Scale (VAS). Pain scores will be assessed at predefined postoperative time points and compared among study groups.
Measured: Before stimulation in the post-anesthesia care unit, immediately after stimulation, 2 hours after surgery, and 24 hours after surgery
Rescue analgesic use
Number of participants requiring rescue analgesics and total rescue analgesic administration during the first 24 postoperative hours.
Measured: Within 24 hours after surgery
Postoperative nausea and vomiting (PONV)
Incidence of postoperative nausea and/or vomiting and use of rescue antiemetic medication during the postoperative period.
Measured: Within 24 hours after surgery
Heart rate changes
Changes in heart rate measured immediately before and immediately after transauricular vagus nerve stimulation sessions as an indicator of autonomic nervous system activity.
Measured: Immediately before and immediately after each stimulation session (preoperative and postoperative).
Quality of Recovery (QoR-15 Score)
Quality of postoperative recovery assessed using the 15-item Quality of Recovery questionnaire (QoR-15). Higher scores indicate better recovery.
Measured: Baseline (preoperative) and 24 hours after surgery.
Adverse events related to transauricular Vagus Nerve Stimulation
Incidence of adverse events potentially related to the intervention, including auricular discomfort, skin irritation, headache, bradycardia, hypotension, bronchospasm, or other treatment-related events.
Measured: From the first stimulation session until 24 hours after surgery.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted8 Jun 2026
- Study start1 Jun 2026 (estimated)
- Primary completion30 Nov 2026 (estimated)
- Study completion4 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Postoperative PainStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Participants will be randomly assigned in a 1:1:1 ratio to receive high-frequency transauricular vagus nerve stimulation (60-120 Hz), low-frequency transauricular vagus nerve stimulation (10-20 Hz), or sham stimulation. Each participant will remain in the assigned group throughout the study and will receive two stimulation sessions, one before anesthesia and one after surgery. Outcomes will be compared across the three parallel groups.
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 174 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Federal University of Bahia
- Sponsor type
- University, hospital or other
- Collaborators
- Faculdade de Medicina de Botucatu, UNESP, Botucatu, Brasil
- Responsible party
- Principal investigator, Joao Paulo Aureliano de Carvalho, Federal University of Bahia
- Investigators
- Rodrigo M Vieira, MD, Principal investigator, Botucatu Medical School, São Paulo State University (UNESP)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07633444
- Sponsor's protocol ID
- 96691226.0.0000.0049
- Other IDs
- 96691226.0.0000.0049
- Acronym
- TVNS-PAIN
- Status last verified
- May 2026
- First submitted
- 2 Jun 2026
- Last updated
- 10 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: 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.
Study at a glance
From the registry record, last updated by the sponsor on 10 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Different Frequencies of Transauricular Vagus Nerve Stimulation on Postoperative Pain: A Randomized, Double-Blind, Sham-Controlled Trial With Preoperative and Postoperative Sessions
- ClinicalTrials.gov ID
- NCT07633444
- Acronym / sponsor ID
- TVNS-PAIN / 96691226.0.0000.0049
- Conditions
- Postoperative Pain, Postoperative Nausea and Vomiting (PONV), Opioid Consumption, Postoperative
- Keywords
- Postoperative Pain, Transauricular Vagus Nerve Stimulation, tVNS, Neuromodulation, Opioid Consumption, Pain Management, Randomized Controlled Trial
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 174 participants (estimated)
- Lead sponsor
- Federal University of BahiaUniversity, hospital or other
- Collaborators
- Faculdade de Medicina de Botucatu, UNESP, Botucatu, Brasil
- Study start
- 1 Jun 2026 (estimated)
- Primary completion
- 30 Nov 2026 (estimated)
- Study completion
- 4 Dec 2026 (estimated)
- First posted
- 8 Jun 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
Postoperative pain remains a major challenge in perioperative care and is associated with delayed recovery, increased healthcare utilization, and greater opioid consumption. Despite advances in multimodal analgesia, opioid medications continue to play a central role in postoperative pain management and may be associated with adverse effects such as nausea, vomiting, respiratory depression, and prolonged recovery. Therefore, the development of effective non-pharmacological adjunctive strategies is of considerable clinical interest.
Transauricular vagus nerve stimulation (tVNS) is a non-invasive neuromodulation technique that stimulates the auricular branch of the vagus nerve through the external ear. Experimental and clinical studies suggest that vagal stimulation may modulate pain perception through activation of central autonomic pathways, enhancement of descending inhibitory pain mechanisms, and regulation of inflammatory responses. Previous clinical trials have demonstrated promising effects of tVNS on acute and chronic pain conditions, including reductions in postoperative pain scores.
However, the optimal stimulation parameters for perioperative analgesia remain uncertain. In particular, the influence of stimulation frequency on clinical outcomes and autonomic responses has not been adequately investigated. Different stimulation frequencies may activate distinct neural pathways and produce different effects on pain modulation and autonomic regulation.
This study is designed to evaluate the effects of different frequencies of transauricular vagus nerve stimulation applied before and after surgery in adult patients undergoing elective surgical procedures. In addition to assessing postoperative opioid requirements, the study will explore the relationship between autonomic responses and postoperative recovery. The findings may contribute to the optimization of non-pharmacological analgesic strategies and support the incorporation of transauricular vagus nerve stimulation into multimodal perioperative pain management protocols.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 3
- Model description
- Participants will be randomly assigned in a 1:1:1 ratio to receive high-frequency transauricular vagus nerve stimulation (60-120 Hz), low-frequency transauricular vagus nerve stimulation (10-20 Hz), or sham stimulation. Each participant will remain in the assigned group throughout the study and will receive two stimulation sessions, one before anesthesia and one after surgery. Outcomes will be compared across the three parallel groups.
| Arm | Type | Receives |
|---|---|---|
| High-Frequency tVNS | Experimental | Device: Transauricular Vagus Nerve Stimulation (tVNS)Participants 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 | Experimental | Device: Transauricular Vagus Nerve Stimulation (tVNS)Participants 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 comparator | Device: Sham Transauricular Vagus Nerve Stimulation (sham tVNS)Participants 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. |
Who may qualify
- Ages
- 18 to 59 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- 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.
Key exclusion criteria (10 listed)
- History of neurological disorders.
- History of psychiatric disorders.
- Inability to understand study procedures.
- Pregnancy.
- Cognitive impairment.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Transauricular Vagus Nerve Stimulation (tVNS)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. | Device | High-Frequency tVNS, Low-Frequency tVNS |
| Sham Transauricular Vagus Nerve Stimulation (sham tVNS)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. | Device | Sham tVNS |
Primary outcome
Total postoperative opioid consumption during the first 24 hours after surgery
Time frame: 24 hours after surgery
Total opioid consumption during the first 24 postoperative hours, recorded according to the institutional postoperative analgesia protocol.
6 secondary outcomes
Postoperative pain intensity (VAS)
Time frame: Before stimulation in the post-anesthesia care unit, immediately after stimulation, 2 hours after surgery, and 24 hours after surgery
Rescue analgesic use
Time frame: Within 24 hours after surgery
Postoperative nausea and vomiting (PONV)
Time frame: Within 24 hours after surgery
Heart rate changes
Time frame: Immediately before and immediately after each stimulation session (preoperative and postoperative).
Quality of Recovery (QoR-15 Score)
Time frame: Baseline (preoperative) and 24 hours after surgery.
Adverse events related to transauricular Vagus Nerve Stimulation
Time frame: From the first stimulation session until 24 hours after surgery.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Jun 2026.
- Individual participant dataSharing planned: Yes. 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.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Rodrigo M Vieira, MD principal investigator
Botucatu Medical School, São Paulo State University (UNESP)
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Transauricular Vagus Nerve Stimulation (tVNS) in people with Postoperative Pain and Postoperative Nausea and Vomiting (PONV), run by Federal University of Bahia at 1 site in Brazil.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 10 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Brazil. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Rodrigo L Alves, MD, PhD (71 99961-9818, rlalves@ufba.br), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Total postoperative opioid consumption during the first 24 hours after surgery (time frame: 24 hours after surgery). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Jun 2026.