Burst SuppressionNCT07081672
Impact of Interscalene Block Combined With General Anesthesia on Burst Suppression in Shoulder Surgery Patients
A study testing Ultrasound-guided interscalene brachial plexus block (ISB) in people with Burst Suppression and Electroencephalogram, run by Bezmialem Vakif University at 1 site in Turkey (Türkiye).
Trial summary
This prospective, randomized, double-blind clinical study aimed to investigate the effects of combining general anesthesia with an interscalene brachial plexus block (ISB) on burst suppression ratio (BSR) and electroencephalographic (EEG) activity in patients undergoing elective shoulder surgery. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Burst Suppression, Electroencephalogram, Interscalene Brachial Plexus Block
- What is being tested?
- Ultrasound-guided interscalene brachial plexus block (ISB)
- Type of treatment
- Injection or infusion, Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 50 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 29 Jan 2025to 20 Jul 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Patients classified as ASA Physical Status I-III
- Aged between 18 and 65 years
- Scheduled for elective shoulder surgery under general anesthesia, with or without interscalene brachial plexus block
Who cannot join
- Advanced renal failure
- Advanced hepatic failure
- Body mass index (BMI) > 40 kg/m²
- History of central nervous system disorders
- Diagnosed psychiatric illness
- History of substance abuse
Show all 13Show fewer
- Known allergy to any of the drugs used in the study
- Refusal to participate or to provide informed consent
- Termination Criteria:
- Severe hypotension (mean arterial pressure < 50 mmHg despite treatment)
- Severe bradycardia (heart rate < 40 bpm requiring intervention)
- Profound hypoxia (SpO₂ < 90% despite oxygen support)
- Drug-related allergic reactions
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Bezmialem Vakif University
Istanbul, Fatih, 34093
About this study
Official title: The Effect of Interscalene Brachial Plexus Block Combined With General Anesthesia on Burst Suppression Ratio in Patients Undergoing Shoulder Surgery
This prospective, randomized, double-blind clinical study aimed to investigate the effects of combining general anesthesia with an interscalene brachial plexus block (ISB) on burst suppression ratio (BSR) and electroencephalographic (EEG) activity in patients undergoing elective shoulder surgery. A total of 50 patients were allocated into two groups: those receiving general anesthesia with ISB (Group B) and those receiving general anesthesia alone (Group K). Intraoperative EEG recordings were obtained from frontal electrodes (Fp1, Fp2, F7, F8) using a SedLine® monitor. Power spectral analysis was conducted for delta, theta, alpha, and beta frequency bands, alongside assessment of Patient State Index (PSI) and BSR.
Read the detailed description
This prospective, randomized, double-blind clinical trial was conducted to evaluate the neurophysiological effects of combining interscalene brachial plexus block (ISB) with general anesthesia in patients undergoing elective shoulder surgery. The primary objective was to investigate how ISB influences intraoperative burst suppression ratio (BSR) and EEG-derived brain activity, using quantitative parameters such as power spectral densities of frequency bands and Patient State Index (PSI).
A total of 50 ASA I-III patients scheduled for shoulder surgery were randomly assigned into two groups: Group B (general anesthesia + ISB) and Group K (general anesthesia only). Standardized general anesthesia was maintained with sevoflurane in both groups. EEG data were recorded continuously using a SedLine® monitor from frontal electrodes (Fp1, Fp2, F7, F8) during four perioperative phases. Spectral analysis was performed using Fast Fourier Transform (FFT) and Welch's method to quantify power in the delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), and beta (13-30 Hz) bands. BSR was calculated based on the duration of EEG suppression epochs, while PSI and SEF (Spectral Edge Frequency) were recorded continuously.
- Being tested
- Ultrasound-guided interscalene brachial plexus block (ISB), General Anesthesia (control group)
- Keywords
- burst supression, electroencephalogram, interscalene brachial plexus block, general anesthesia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Ultrasound-guided interscalene brachial plexus block (ISB)Procedure or surgery
The intervention consisted of an ultrasound-guided interscalene brachial plexus block (ISB) administered to patients in Group B prior to general anesthesia. The block was performed using a posterior in-plane approach with real-time ultrasound visualization. A total of 20 mL of 0.125% bupivacaine was injected around the C5-C6 nerve roots under sterile conditions by experienced anesthesiologists.
General Anesthesia (control group)Procedure or surgery
General anesthesia without regional block
| Study group | Role | What they receive |
|---|---|---|
| Patients in Group B received an ultrasound-guided interscalene brachial plexus block (ISB) | Active comparator | A total of 20 mL of 0.125% bupivacaine was administered around the C5-C6 nerve roots under real-time ultrasound visualization. Fifteen minutes after the block, both sensory and motor block assessments were performed to confirm effectiveness. Following confirmation of a successful block, a standardized general anesthesia protocol was initiated using 1-2 mg/kg propofol, 1 mcg/kg fentanyl, and 0.6 mg/kg rocuronium, followed by endotracheal intubation. Anesthesia was maintained with sevoflurane (1.0-1.3 MAC), and depth of anesthesia was continuously monitored using the SedLine® EEG monitor. Receives: Procedure: Ultrasound-guided interscalene brachial plexus block (ISB) |
| Patients in Group K did not receive any regional anesthesia prior to general anesthesia induction. | Active comparator | After standard monitoring was established, including ECG, non-invasive blood pressure, SpO₂, and SedLine® EEG monitoring, a 5-minute baseline EEG recording (Phase 0) was obtained with the patient at rest, eyes closed, and in a noise-minimized environment. Subsequently, general anesthesia was induced using 1-2 mg/kg propofol, 1 mcg/kg fentanyl, and 0.6 mg/kg rocuronium, followed by endotracheal intubation. Anesthesia was maintained with sevoflurane at 1.0-1.3 MAC in a mixture of 50% oxygen and air. To ensure adequate intraoperative analgesia, a remifentanil infusion (0.05-0.2 μg/kg/min) was administered and titrated according to Surgical Pleth Index (SPI) values, aiming to maintain SPI between 20-50. Receives: Procedure: General Anesthesia (control group) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Burst Suppression Ratio (BSR)
Burst Suppression Ratio (BSR): The main quantitative indicator of deep cortical suppression, calculated as the percentage of time the EEG signal remained in a suppression state (defined as amplitude <±10 μV for ≥0.5 seconds) during surgery. BSR was recorded continuously and analyzed across four perioperative phases (Phase 0-3).
Measured: peroperative
Power Spectral Density (PSD) Analysis
The average spectral power (μV²) of EEG signals was analyzed for four conventional frequency bands-delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), and beta (13-30 Hz)-using FFT-based spectral analysis. These values were calculated from frontal electrodes (Fp1, Fp2, F7, F8), and comparisons were made between Group B (ISB group) and Group K (control group) at each phase.
Measured: peroperative
Patient State Index (PSI)
The Patient State Index (PSI), a proprietary quantitative measure ranging from 0 to 100, is derived from multichannel electroencephalogram (EEG) signals using the SedLine® brain function monitoring system. Higher PSI values indicate lighter levels of anesthesia or increased cortical activity, whereas lower values correspond to deeper anesthetic states. In this study, PSI values were utilized to monitor the level of consciousness and cortical stability during the intraoperative period. Particular emphasis was placed on PSI trends observed during Phase 1 (following the administration of the interscalene block but prior to the induction of general anesthesia), in order to investigate any pre-anesthetic central nervous system effects attributable to the regional block.
Measured: peroperative
Secondary outcomes (6)
Mean Arterial Pressure (MAP)
Intraoperative mean arterial pressure (MAP) was continuously monitored and recorded at predefined intervals throughout the procedure. Particular attention was paid to measurements taken during anesthesia induction, surgical positioning in the beach chair position, and skin incision. These data were analyzed to evaluate hemodynamic stability and to investigate the potential sympatholytic effects of the interscalene brachial plexus block (ISB).
Measured: peroperative
Anesthetic and Analgesic Drug Consumption
Total doses of intraoperative sevoflurane, remifentanil, and propofol were recorded for each patient. Volatile anesthetic consumption was quantified in minimum alveolar concentration-hours (MAC-h). The aim was to evaluate whether ISB reduced the requirement for hypnotic and opioid agents during surgery.
Measured: peroperative
Postoperative Pain Scores
Postoperative pain intensity was assessed using the Numerical Rating Scale (NRS), which ranges from 0 (no pain) to 10 (worst imaginable pain). Higher scores indicate greater pain severity. Pain scores were recorded during the post-anesthesia care unit (PACU) stay, specifically within the first two hours following surgery, to evaluate early postoperative analgesia.
Measured: During PACU stay (up to 2 hours)
Nursing Delirium Screening Scale (NUDESC)
The Nursing Delirium Screening Scale (NU-DESC) is a validated, nurse-administered tool used to detect signs of postoperative delirium. It assesses five domains: disorientation, inappropriate behavior, inappropriate communication, illusions/hallucinations, and psychomotor retardation. Each domain is scored from 0 to 2, resulting in a total score ranging from 0 to 10. A total score of ≥2 indicates a high probability of delirium. In this study, NU-DESC scores were recorded during the early postoperative period to identify any acute cognitive changes.
Measured: During PACU stay (up to 2 hours)
Heart Rate (HR)
Heart rate (HR) was continuously monitored intraoperatively and recorded at specified time points, with focused analysis during key phases such as anesthesia induction, patient positioning (beach chair position), and surgical incision. Group comparisons were made to assess ISB-associated modulation of cardiac autonomic response.
Measured: peroperative
Oxygen Saturation (SpO₂)
Peripheral oxygen saturation (SpO₂) was monitored continuously during surgery and recorded at predetermined intervals. Measurements during critical phases, including induction, positioning, and incision, were evaluated to ensure adequate oxygenation and assess any indirect effects of ISB on respiratory function.
Measured: peroperative
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Jul 2025
- Study start29 Jan 2025
- Primary completion15 Jul 2025
- Study completion20 Jul 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Burst SuppressionStudies of the same condition, open and under way.
- More trials run by Bezmialem Vakif UniversityThe sponsor's other registered studies.
- 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
- Screening
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 50 participants (actual)
Sponsor and investigators
- Lead sponsor
- Bezmialem Vakif University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Tugba KOK, Bezmialem Vakif University
- Investigators
- Kazım Karaaslan, MD, Study director, Bezmialem Vakif University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07081672
- Sponsor's protocol ID
- Tugba07
- Status last verified
- Jul 2025
- First submitted
- 2 Jul 2025
- Last updated
- 30 Jul 2025
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 30 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Interscalene Brachial Plexus Block Combined With General Anesthesia on Burst Suppression Ratio in Patients Undergoing Shoulder Surgery
- ClinicalTrials.gov ID
- NCT07081672
- Acronym / sponsor ID
- Tugba07
- Keywords
- burst supression, electroencephalogram, interscalene brachial plexus block, general anesthesia
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 50 participants (actual)
- Lead sponsor
- Bezmialem Vakif UniversityUniversity, hospital or other
- Study start
- 29 Jan 2025 (actual)
- Primary completion
- 15 Jul 2025 (actual)
- Study completion
- 20 Jul 2025 (actual)
- First posted
- 23 Jul 2025 (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.
This prospective, randomized, double-blind clinical study aimed to investigate the effects of combining general anesthesia with an interscalene brachial plexus block (ISB) on burst suppression ratio (BSR) and electroencephalographic (EEG) activity in patients undergoing elective shoulder surgery. A total of 50 patients were allocated into two groups: those receiving general anesthesia with ISB (Group B) and those receiving general anesthesia alone (Group K). Intraoperative EEG recordings were obtained from frontal electrodes (Fp1, Fp2, F7, F8) using a SedLine® monitor. Power spectral analysis was conducted for delta, theta, alpha, and beta frequency bands, alongside assessment of Patient State Index (PSI) and BSR.
Detailed description
This prospective, randomized, double-blind clinical trial was conducted to evaluate the neurophysiological effects of combining interscalene brachial plexus block (ISB) with general anesthesia in patients undergoing elective shoulder surgery. The primary objective was to investigate how ISB influences intraoperative burst suppression ratio (BSR) and EEG-derived brain activity, using quantitative parameters such as power spectral densities of frequency bands and Patient State Index (PSI).
A total of 50 ASA I-III patients scheduled for shoulder surgery were randomly assigned into two groups: Group B (general anesthesia + ISB) and Group K (general anesthesia only). Standardized general anesthesia was maintained with sevoflurane in both groups. EEG data were recorded continuously using a SedLine® monitor from frontal electrodes (Fp1, Fp2, F7, F8) during four perioperative phases. Spectral analysis was performed using Fast Fourier Transform (FFT) and Welch's method to quantify power in the delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), and beta (13-30 Hz) bands. BSR was calculated based on the duration of EEG suppression epochs, while PSI and SEF (Spectral Edge Frequency) were recorded continuously.
Study design
- Primary purpose
- Screening
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Patients in Group B received an ultrasound-guided interscalene brachial plexus block (ISB) | Active comparator | Procedure: Ultrasound-guided interscalene brachial plexus block (ISB)A total of 20 mL of 0.125% bupivacaine was administered around the C5-C6 nerve roots under real-time ultrasound visualization. Fifteen minutes after the block, both sensory and motor block assessments were performed to confirm effectiveness. Following confirmation of a successful block, a standardized general anesthesia protocol was initiated using 1-2 mg/kg propofol, 1 mcg/kg fentanyl, and 0.6 mg/kg rocuronium, followed by endotracheal intubation. Anesthesia was maintained with sevoflurane (1.0-1.3 MAC), and depth of anesthesia was continuously monitored using the SedLine® EEG monitor. |
| Patients in Group K did not receive any regional anesthesia prior to general anesthesia induction. | Active comparator | Procedure: General Anesthesia (control group)After standard monitoring was established, including ECG, non-invasive blood pressure, SpO₂, and SedLine® EEG monitoring, a 5-minute baseline EEG recording (Phase 0) was obtained with the patient at rest, eyes closed, and in a noise-minimized environment. Subsequently, general anesthesia was induced using 1-2 mg/kg propofol, 1 mcg/kg fentanyl, and 0.6 mg/kg rocuronium, followed by endotracheal intubation. Anesthesia was maintained with sevoflurane at 1.0-1.3 MAC in a mixture of 50% oxygen and air. To ensure adequate intraoperative analgesia, a remifentanil infusion (0.05-0.2 μg/kg/min) was administered and titrated according to Surgical Pleth Index (SPI) values, aiming to maintain SPI between 20-50. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Patients classified as ASA Physical Status I-III
- Aged between 18 and 65 years
- Scheduled for elective shoulder surgery under general anesthesia, with or without interscalene brachial plexus block
Key exclusion criteria (13 listed)
- Advanced renal failure
- Advanced hepatic failure
- Body mass index (BMI) > 40 kg/m²
- History of central nervous system disorders
- Diagnosed psychiatric illness
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 |
|---|---|---|
| Ultrasound-guided interscalene brachial plexus block (ISB)The intervention consisted of an ultrasound-guided interscalene brachial plexus block (ISB) administered to patients in Group B prior to general anesthesia. The block was performed using a posterior in-plane approach with real-time ultrasound visualization. A total of 20 mL of 0.125% bupivacaine was injected around the C5-C6 nerve roots under sterile conditions by experienced anesthesiologists. | Procedure or surgery | Patients in Group B received an ultrasound-guided interscalene brachial plexus block (ISB) |
| General Anesthesia (control group)General anesthesia without regional block | Procedure or surgery | Patients in Group K did not receive any regional anesthesia prior to general anesthesia induction. |
Primary outcome
Burst Suppression Ratio (BSR)
Time frame: peroperative
Burst Suppression Ratio (BSR): The main quantitative indicator of deep cortical suppression, calculated as the percentage of time the EEG signal remained in a suppression state (defined as amplitude <±10 μV for ≥0.5 seconds) during surgery. BSR was recorded continuously and analyzed across four perioperative phases (Phase 0-3).
Power Spectral Density (PSD) Analysis
Time frame: peroperative
The average spectral power (μV²) of EEG signals was analyzed for four conventional frequency bands-delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), and beta (13-30 Hz)-using FFT-based spectral analysis. These values were calculated from frontal electrodes (Fp1, Fp2, F7, F8), and comparisons were made between Group B (ISB group) and Group K (control group) at each phase.
Patient State Index (PSI)
Time frame: peroperative
The Patient State Index (PSI), a proprietary quantitative measure ranging from 0 to 100, is derived from multichannel electroencephalogram (EEG) signals using the SedLine® brain function monitoring system. Higher PSI values indicate lighter levels of anesthesia or increased cortical activity, whereas lower values correspond to deeper anesthetic states. In this study, PSI values were utilized to monitor the level of consciousness and cortical stability during the intraoperative period. Particular emphasis was placed on PSI trends observed during Phase 1 (following the administration of the interscalene block but prior to the induction of general anesthesia), in order to investigate any pre-anesthetic central nervous system effects attributable to the regional block.
6 secondary outcomes
Mean Arterial Pressure (MAP)
Time frame: peroperative
Anesthetic and Analgesic Drug Consumption
Time frame: peroperative
Postoperative Pain Scores
Time frame: During PACU stay (up to 2 hours)
Nursing Delirium Screening Scale (NUDESC)
Time frame: During PACU stay (up to 2 hours)
Heart Rate (HR)
Time frame: peroperative
Oxygen Saturation (SpO₂)
Time frame: peroperative
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Jul 2025.
- Individual participant dataSharing planned: No
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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. This study is not recruiting at the moment.
Kazım Karaaslan, MD study director
Bezmialem Vakif University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Ultrasound-guided interscalene brachial plexus block (ISB) in people with Burst Suppression and Electroencephalogram, run by Bezmialem Vakif University at 1 site in Turkey (Türkiye).
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 3 inclusion and 13 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: finished, as of the sponsor's last update on 30 Jul 2025. 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 Turkey (Türkiye). 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. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Burst Suppression Ratio (BSR) (time frame: peroperative). The study lists 3 primary outcomes in all. 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 30 Jul 2025.