SPENG Block Versus Superior Trunk Block for Shoulder Surgery: Effects on Diaphragmatic Function, Mechanical Power, Nociception, and Analgesia: A Randomized Controlled Trial

November 7, 2026 updated by: Nurullah Damla, Bursa Yuksek Ihtisas Training and Research Hospital

COMPARİSON OF THE EFFECTS OF ULTRASOUND-GUİDED PREOPERATİVE SHOULDER POSTERİOR PERİCAPSULAR NERVE GROUP (SPENG) BLOCK AND SUPERİOR TRUNK BLOCK ON DİAPHRAGMATİC FUNCTİON, INTRAOPERATİVE MECHANİCAL POWER, NOCİCEPTİON (QNOX), AND POSTOPERATİVE ANALGESİA İN UPPER EXTREMİTY AND SHOULDER SURGERY: A PROSPECTİVE RANDOMİZED CONTROLLED TRİAL

Shoulder and upper extremity surgery causes severe postoperative pain. The interscalene brachial plexus block is the standard regional analgesia technique, but it causes ipsilateral hemidiaphragmatic paralysis (HDP) in almost all patients because of its proximity to the phrenic nerve. This can lead to dyspnea, hypoxemia, and atelectasis, especially in obese, elderly, or respiratory-compromised patients. The superior trunk block (STB) has been proposed as a phrenic-sparing alternative, yet HDP still occurs in about 70-76% of patients.

The Shoulder Posterior Pericapsular Nerve Group (SPENG) block is a novel pericapsular technique that targets the articular branches of the suprascapular and axillary nerves with a single injection posterior to the scapula, far from the brachial plexus and phrenic nerve. No randomized controlled trial has yet compared the SPENG block with the STB.

The aim of this prospective, randomized controlled trial is to compare preoperative ultrasound-guided SPENG block and STB in adult patients undergoing elective shoulder and upper extremity surgery under general anesthesia. The primary outcome is the incidence of hemidiaphragmatic paralysis, assessed by M-mode ultrasound measurement of diaphragmatic excursion in the post-anesthesia care unit. Secondary outcomes include intraoperative mechanical power and respiratory mechanics, intraoperative nociception (qNOX) and additional opioid requirement, Visual Analog Scale (VAS) pain scores and rescue analgesic consumption during the first 24 postoperative hours, and patient satisfaction.

The investigators hypothesize that the SPENG block will significantly reduce the incidence of hemidiaphragmatic paralysis compared with the STB while providing similar analgesic quality during the first 24 postoperative hours.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Rationale

After superior trunk block (STB), hemidiaphragmatic paralysis (HDP) has been reported in 76.3% of patients (Kang et al., Anesthesiology 2019) and in 70.8% of patients with 20 mL of local anesthetic (Lee et al., Pain Physician 2021). Even after ultrasound-guided supraclavicular block, the reported HDP incidence is 59.5% (Ferré et al., 2019). These data suggest that all approaches at the level of the brachial plexus carry a substantial risk of phrenic nerve involvement. The SPENG block (Kilicaslan et al., Pain Med 2026) targets the articular branches of the suprascapular and axillary nerves, which provide approximately 70% of the sensory innervation of the shoulder joint, at a site posterior to the scapula. M-mode ultrasound assessment of diaphragmatic excursion is a non-invasive, repeatable, and objective bedside method for detecting block-related HDP.

Randomization and Blinding Procedures

The allocation sequence will be generated by computer (www.random.org) and concealed in sequentially numbered, opaque, sealed envelopes. Each envelope will be opened immediately before the block by the anesthesiologist performing it, who will not be involved in data collection. To maintain blinding, identical sterile dressings will be applied to both the supraclavicular region and the posterior shoulder in all patients. All block procedures will be performed with real-time needle-tip visualization, in 5 mL increments with aspiration before each increment. Lipid emulsion (20%) and resuscitation equipment will be available.

Standardized Perioperative Management

Standard monitoring will be applied in all patients. IV midazolam 1-2 mg may be given after baseline diaphragm measurement. Anesthesia will be induced with propofol 2-2.5 mg/kg, fentanyl 1 µg/kg, and rocuronium 0.6 mg/kg, and maintained with sevoflurane titrated to a qCON of 40-60. Fentanyl 0.5 µg/kg will be administered if qNOX remains above 60 for more than 1 minute. All patients will receive IV paracetamol 1 g and ondansetron 4 mg 30 minutes before the end of surgery. Ventilation will be standardized in volume-controlled mode (tidal volume 6-8 mL/kg ideal body weight, PEEP 5 cmH₂O, FiO₂ 50%, respiratory rate adjusted to EtCO₂ 35-40 mmHg). Plateau pressure will be measured with a 0.5-second inspiratory pause, and mechanical power will be calculated with the simplified Gattinoni formula: MP (J/min) = 0.098 × RR × VT (L) × [Ppeak - ½ × (Pplat - PEEP)]. Postoperative analgesia will consist of IV paracetamol 1 g every 6 hours and IV dexketoprofen 50 mg every 12 hours unless contraindicated, with IV tramadol 1 mg/kg (maximum 400 mg/24 h) as rescue analgesia.

Diaphragm Ultrasound Technique

The ipsilateral hemidiaphragm will be imaged in the supine position with a 2-5 MHz convex probe using a subcostal approach along the anterior axillary/midclavicular line (liver window on the right, spleen window on the left). Excursion will be measured three times in M-mode during each maneuver, and the mean value will be recorded. The postoperative measurement will be performed when the patient is fully awake and cooperative (Modified Aldrete score ≥9), using the same position, probe placement, and maneuvers, by the same blinded assessor.

Sample Size and Statistical Analysis

Sample size was calculated with G*Power 3.1.9.7 based on the primary outcome. Assuming an HDP incidence of 70% with STB and a conservatively estimated 30% with SPENG, 31 patients per group are required (two-sided α = 0.05, power = 90%). Allowing for an anticipated 15% loss, 36 patients will be enrolled per group. This sample size is also sufficient to detect a 1.5-point (SD 2.0) difference in VAS scores with 80% power. Data will be analyzed with SPSS v26.0. Relative risk with 95% confidence interval will be reported for the primary outcome. Repeated measures ANOVA or linear mixed-effects models will be used for time-dependent variables, and Kaplan-Meier analysis with the log-rank test for time to first rescue analgesic. Analyses will follow a modified intention-to-treat approach, and p < 0.05 will be considered statistically significant.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
72

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

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Study Locations

  • Turkey (Türkiye)
    • Bursa
      • Bursa, Bursa, Turkey (Türkiye), 16310
        • University of Health Sciences, Bursa Yüksek İhtisas Training and Research Hospital
        • Contact:
        • Principal Investigator:
          • Korgün Ökmen, MD
        • Sub-Investigator:
          • Kamer Kılınç, MD
        • Sub-Investigator:
          • Nurullah Damla, MD
        • Sub-Investigator:
          • Furkan Sakın, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Age 18 years or older
  • American Society of Anesthesiologists (ASA) physical status I-III
  • Scheduled for elective arthroscopic or open shoulder/upper extremity surgery under general anesthesia
  • Ipsilateral hemidiaphragm clearly visualized with M-mode ultrasound at baseline assessment
  • Signed written informed consen

Exclusion Criteria:

  • Contraindication to regional anesthesia: local infection at the injection site, coagulopathy, or anticoagulant therapy (INR >1.5, platelet count <100,000/mm3)
  • Known allergy to local anesthetics
  • Known ipsilateral or contralateral diaphragmatic paralysis/dysfunction or history of phrenic nerve injury
  • Severe respiratory disease (COPD with mMRC dyspnea scale ≥2, restrictive lung disease, home oxygen requirement) or baseline room-air SpO2 <94%
  • Body mass index ≥35 kg/m2
  • Pre-existing neurological deficit or brachial plexopathy in the operative extremity
  • Regular opioid use for chronic pain within the past 3 months
  • Pregnancy or breastfeeding
  • Neurological or psychiatric disease preventing cooperation or understanding of the VAS scale, or refusal to give consent

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: SPENG Block

Participants will receive an ultrasound-guided Shoulder Posterior Pericapsular Nerve Group (SPENG) block with 20 mL of 0.25% bupivacaine before induction of general anesthesia.
Procedure: SPENG Block

With the patient in the lateral decubitus position, a linear probe is placed transversely just inferior to the posterior acromion. Using an in-plane medial-to-lateral approach, the needle tip is positioned between the posterior glenoid rim and the deep surface of the infraspinatus muscle, and 20 mL of 0.25% bupivacaine is injected as a single injection.
Active Comparator: Superior Trunk Block

Participants will receive an ultrasound-guided superior trunk block with 20 mL of 0.25% bupivacaine before induction of general anesthesia.
Procedure: Superior Trunk Block

With the patient supine and the head turned to the contralateral side, the superior trunk is identified at the level just proximal to the origin of the suprascapular nerve. Using an in-plane lateral-to-medial approach, 20 mL of 0.25% bupivacaine is injected, half anterior and half posterior to the superior trunk.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Incidence of Hemidiaphragmatic Paralysis
Time Frame: Baseline (before block) and approximately 30 minutes after admission to the post-anesthesia care unit

Ipsilateral diaphragmatic excursion will be measured with M-mode ultrasound during the sniff maneuver (mean of three measurements). Hemidiaphragmatic paralysis is defined as a ≥25% reduction in excursion from baseline and graded as none (<25%), partial (25-75%), or complete (>75% reduction or paradoxical movement).
Baseline (before block) and approximately 30 minutes after admission to the post-anesthesia care unit

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in Diaphragmatic Excursion
Time Frame: Baseline (before block) and approximately 30 minutes after admission to the post-anesthesia care unit

Percentage change in ipsilateral diaphragmatic excursion (mm) measured with M-mode ultrasound during quiet breathing, deep inspiration, and sniff maneuver, calculated as ((T0 - T1) / T0) × 100.
Baseline (before block) and approximately 30 minutes after admission to the post-anesthesia care unit
Intraoperative Mechanical Power
Time Frame: 10 minutes after intubation, after surgical positioning, at 30 and 60 minutes of surgery, and at the end of surgery

Mechanical power (J/min) calculated with the simplified Gattinoni formula: 0.098 × RR × VT (L) × [Ppeak - ½ × (Pplat - PEEP)].
10 minutes after intubation, after surgical positioning, at 30 and 60 minutes of surgery, and at the end of surgery
Intraoperative Driving Pressure and Static Compliance
Time Frame: 10 minutes after intubation, after surgical positioning, at 30 and 60 minutes of surgery, and at the end of surgery

Driving pressure (Pplat - PEEP, cmH2O) and static compliance (VT / [Pplat - PEEP], mL/cmH2O).
10 minutes after intubation, after surgical positioning, at 30 and 60 minutes of surgery, and at the end of surgery
Intraoperative Nociception (qNOX)
Time Frame: Before induction, at intubation, surgical positioning, skin incision/first portal entry, every 15 minutes during surgery, and at the end of surgery

qNOX values recorded with the Conox monitor and the percentage of anesthesia time with qNOX >60.
Before induction, at intubation, surgical positioning, skin incision/first portal entry, every 15 minutes during surgery, and at the end of surgery
Intraoperative Supplemental Fentanyl Consumption
Time Frame: Intraoperative period

Total supplemental fentanyl (µg) and number of supplemental doses administered for qNOX >60 lasting longer than 1 minute.
Intraoperative period
Postoperative Pain Scores
Time Frame: On arrival at the post-anesthesia care unit, at 30 minutes, and at 2, 4, 6, 12, and 24 hours postoperatively

Pain assessed with the Visual Analog Scale (0-10 cm; 0 = no pain, 10 = worst imaginable pain) at rest at all time points, and additionally during movement at 24 hours.
On arrival at the post-anesthesia care unit, at 30 minutes, and at 2, 4, 6, 12, and 24 hours postoperatively
Time to First Rescue Analgesic
Time Frame: Postoperative 24 hours

Time (minutes) from the end of surgery to the first administration of rescue tramadol for VAS ≥4.
Postoperative 24 hours
Total Rescue Tramadol Consumption
Time Frame: Postoperative 24 hours

Total intravenous tramadol (mg) administered as rescue analgesia.
Postoperative 24 hours
Patient Satisfaction
Time Frame: Postoperative 24 hours

Assessed with a 5-point Likert scale (1 = very dissatisfied, 5 = very satisfied).
Postoperative 24 hours
Incidence of Block-Related Adverse Events
Time Frame: Postoperative 24 hours

Horner syndrome, hoarseness, vascular puncture, signs of local anesthetic systemic toxicity, postoperative nausea and vomiting, paresthesia, dyspnea, and need for supplemental oxygen.
Postoperative 24 hours

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Block Performance Time
Time Frame: During block procedure

Total time (minutes) for ultrasound imaging and needling.
During block procedure
Motor Block of the Shoulder
Time Frame: 20 minutes after block

Shoulder abduction (axillary nerve) and external rotation (suprascapular nerve) strength assessed with a 3-point scale (2 = normal strength, 1 = reduced strength, 0 = no movement against gravity).
20 minutes after block

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Bursa Yuksek Ihtisas Training and Research Hospital

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Korgün Ökmen, University of Health Sciences, Bursa Yüksek İhtisas Training and Research Hospital

Publications and helpful links

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General Publications

Study record dates

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Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 7, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 7, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 13, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 13, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 7, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • BursaYIERH-AR-ND-02

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared, as the informed consent form does not include permission for data sharing and the Turkish Personal Data Protection Law (KVKK) restricts the disclosure of personal health data. Aggregated results will be published in a peer-reviewed journal.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

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