This study aims to compare the efficacy and safety of ultrasound-guided Interscalene block (ISB) versus Infraspinatus-Teres minor (ITM) interfacial plane block in shoulder arthroscopic surgery.

A prospective, randomized clinical trial will be conducted with 46 patients. Approval was obtained from the Medical Ethics Committee (2022/0126), and written informed consent will be collected from all participants. Patients aged 20-70, ASA I-II, scheduled for arthroscopic shoulder surgery will be divided before the induction of general anesthesia (GA) into two groups:

Group A: will receive the ultrasound guided ISB technique with a 15ml solution of 7.5ml lidocaine 2% and 7.5ml bupivacaine 0.5% be injected between the anterior and middle scalene muscles.

Group B: will receive the ultrasound guided ITM block with the same anesthetic solution be injected between the infraspinatus and teres minor muscles.

Researchers will examine the following outcomes;

1. Primary outcome measure: Efficacy of analgesia by Pain score; will be measured by Numerical Rating Scale (NRS) score (0=no pain,1-3=mild,4-6=moderate,7-9=sever,10=most sever) at postoperative 12 hour.

2. Secondary outcome measures:

   1. Duration of analgesia, starting from recovery from general anesthesia (GA) to 1st time giving the patient rescue analgesia ( measured by NRS pain score at 0, 6 ,12, 18 and 24 postoperative hours)
   2. Risk of complications from techniques
   3. Patient satisfaction after surgery.
   4. Rescue analgesic consumption
   5. Hemodynamics monitoring; measurements of heart rate and mean arterial blood pressure before induction of anesthesia and every 15 minutes during surgery till end of surgery

I. Study design:

Randomized comparative study.

II. Study setting and location:

The study will be conducted at the operative room of Souad Kafafi University Hospital (SKUH), Misr University of science and Technology (MUST).

III. Study population:

Patients aged from 20 to 60 years old scheduled for shoulder surgery will be randomized in a 1:1 ratio after induction of general anesthesia (GA) to either: Group A: Received the ultrasound guided ISB technique with a 15ml solution of 7.5ml lidocaine 2% and 7.5ml bupivacaine 0.5% injected between the anterior and middle scalene muscles.

Group B: Received the ultrasound guided ITM block with the same anesthetic solution injected between the infraspinatus and teres minor muscles.

IV. Study procedures:

1. Randomization Patients will be randomly allocated by a computer-generated table into one of the study groups; the randomization sequence will be concealed in sealed opaque envelopes.

2. Study protocol

   • All Patients will have a pre-operative assessment visit, which will include; history taking, complete physical examination and review of all the results of the routine investigations (CBC, Coagulation profile, renal functions, liver functions).
   • On Arrival to the preparation room, they will receive the following premedication via intravenous (IV) route: Midazolam 0.03 mg/kg, Ondansetron 4 mg and Omeprazole 40 mg iv infusion.
   • Upon Arrival to the operating room, standard monitoring will be applied which include: Pulse Oximeter, Noninvasive Blood Pressure and Six-lead electrocardiogram (ECG).
   • General anesthesia will be induced using: Propofol 1-2mg/kg, Fentanyl1-2 μg/kg, Morphine 0.1mg/kg and Atracurium 0.5 mg/kg.
   • After endotracheal intubation, side way capnography will be applied to measure end tidal CO2 pressure in the expired air.
   • General anesthesia will be maintained using Sevoflurane 1-2 MAC (Mean Alveolar Concentrations) in O2/ Air 50% / 50%, Paracetamol 1gm iv infusion, ketorolac 30 mg iv and incremental doses of Atracurium 0.1mg/kg/30 minutes.

The patients will be randomly allocated into two groups:

Group A:

Ultrasound-guided Interscalene block (ISB) technique.

Group B:

Ultrasound-guided Infraspinatus-teres minor (ITM) interfacial plane block technique

V. Study outcomes:

1. Primary outcome measure:

   • Efficacy of analgesia by Pain score; will be measured by Numerical Rating Scale (NRS) score (0-10; 0=no pain,1-3=mild,4-6=moderate,7-9=sever,10=most sever) at postoperative12 hours.

2. Secondary outcome measures:

   1. Duration of analgesia, starting from recovery from general anesthesia (GA) to 1st time giving the patient rescue analgesia ( measured by NRS pain score at 0, 6 ,12, 18 and 24 postoperative hours).
   2. Risk of complications from techniques.
   3. Patient satisfaction after surgery
   4. Total intraoperative analgesia dose (fentanyl consumption) and total postoperative analgesia dose (morphine consumption).
   5. Hemodynamics monitoring; measurements of heart rate and mean arterial blood pressure before induction of anesthesia and every 15 minutes during surgery till end of surgery

VII. Statistical analysis:

1. Sample size:

   Sample size calculation was based on pain score after Interscalene block (ISB) in shoulder surgery versus other methods retrieved from previous research (Singelyn et al., 2004) (15). Using G power program version 3.1.9.4 to calculate sample size based on effect size of 0.897 (35 ± 25) versus (13±24), using 2-tailed test, α error =0.05 and power = 80.0%, the total calculated sample size will be 21 in each group at least and by adding 10% to compensate for possible drop out then total sample size per group is 23 cases at least.

2. Statistical analysis:

Data will be analyzed using SPSS (statistical package for social sciences) version 22. Quantitative data will be tested for normality by Kolmogrov-Smironv test then described as mean and standard deviation for normally distributed data, and median and range for non-normally distributed, Qualitative data will be presented as number and percent. The appropriate statistical test will be applied according to data type with the following suggested tests: Student t test and Mann Whitney U test for continuous variables, Chi-Square test for categorical variable.

Inclusion Criteria:

• Patients aged 20 to 60,
• ASA classification I or II,
• scheduled for arthroscopic shoulder surgery,
• will be randomized 1:1 into two groups before the induction of general anesthesia (GA)

Exclusion Criteria:

• Patients who refuse participation.
• Have allergies to local anesthetics.
• Phrenic nerve dysfunction.
• Chronic opioid use.
• ASA III or higher classification.
• Coagulopathy.
• Severe chronic obstructive pulmonary disease.
• Local infection at the injection site

Demographic Information: Age, sex, race, and other relevant demographic details.

Baseline Characteristics: Health status, medical history, and any pre-existing conditions prior to the trial.

Treatment Assignment: Information on the intervention or treatment each participant received.

Outcome Measures: Data on primary and secondary outcomes as defined in the trial protocol.

Adverse Events: Reports of any side effects or adverse events experienced by participants during the trial.

Follow-up Data: Information collected during follow-up periods, including long-term outcomes.

01/06//2025 to 31/5/2026

Researchers:

Who: Academic researchers, industry scientists, and regulatory agencies. What: Full IPD, including demographic data, treatment assignments, and outcome measures.

How: Through data sharing platforms or repositories after submitting a research proposal and obtaining necessary approvals.

Regulatory Authorities:

Who: Agencies like the FDA or EMA. What: Full IPD and supporting documentation for oversight and review. How: Direct access during the review process of clinical trial applications.

Data Sharing Initiatives:

Who: Collaborating institutions and consortia. What: Aggregated or anonymized IPD for meta-analyses or systematic reviews. How: Via established partnerships and shared databases.

Public and Patient Advocacy Groups:

Who: Organizations seeking to promote transparency. What: Summary data and aggregated results, but not individual-level data. How: Through publicly available reports or dashboards.

The participants, care providers and outcome assessor will be blind regarding the procedure