Comparison of the Interscalene Block Alone Versus Combined With Superior Truncus Block During Shoulder Surgery in Diaphragmatic Function

Phrenic Nerve Sparing of the Interscalene Block Alone Versus Combined With Superior Truncus Block During Shoulder Surgery , Prospective Comparative Randomized Study

Primarily, This study aims to compare between interscalene block alone versus combined with superior truncus block in producing diaphragmatic paralysis and Secondarily aims to evaluate

1. Effect on the pulmonary function.
2. Duration of the sensory and motor block.
3. Postoperative analgesic consumption.
4. Any complications or side effects during shoulder surgery.

Study Overview

• Status: Not yet recruiting
• Conditions: Diaphragm Issues
• Intervention / Treatment: Other: Regional anesthesia in shoulder surgery

Detailed Description

Regional anesthesia is central to modern shoulder surgery because it provides excellent perioperative analgesia, reduces opioid consumption, and facilitates early rehabilitation. The interscalene brachial plexus block (ISB) has long been considered the gold-standard single-shot regional technique for shoulder procedures due to its reliable analgesia and surgical anesthesia. However, ISB commonly causes ipsilateral hemidiaphragmatic paresis (HDP) from unintended phrenic nerve blockade, which can produce clinically important declines in pulmonary function and may be poorly tolerated in patients with limited respiratory reserve.

To minimize phrenic involvement while preserving analgesic effectiveness, more selective approaches have been proposed. The superior trunk block (STB) - performed at the level where C5-C6 fibers form the superior trunk - aims to anesthetize the shoulder innervation more distally and thus reduce spread to the phrenic nerve. A landmark randomized trial and subsequent studies reported that STB provides analgesia comparable to ISB while greatly lowering the incidence of HDP (for example, ISB 71% vs STB 5% in one trial). Systematic reviews and meta-analyses since then have reinforced STB as an effective phrenic-sparing alternative for many shoulder procedures.

Despite encouraging data for STB, the literature is not entirely uniform. Some randomized trials and observational reports have found either reduced anesthetic quality with STB or smaller-than-expected reductions in phrenic involvement, particularly when block technique, local anesthetic volume, or patient anatomy differ. Moreover, combining blocks (for example, ISB with selective superior-trunk targeting or other modifications) has been proposed as a strategy to balance surgical anesthesia and respiratory safety, but comparative prospective data examining the effect of ISB alone versus ISB combined with STB on diaphragmatic function are limited. This uncertainty is important because even partial diaphragmatic paresis can degrade postoperative pulmonary mechanics and increase complications in vulnerable patients.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Sherif Salah Ismail Assistant lecturer of Anesthesia; Phone Number: 01007272718; Email: sherifsalah383@gmail.com
• Study Contact Backup: Name: El hadad Ali Mosa Professor of Anesthesia; Phone Number: 01019816967

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• ASA (American Society of Anesthesiologists) I, II physical status.
• Aged between 20 and 65 years.
• Male or female.
• Body Mass index (BMI): 18-30 kg/m3.
• Scheduled for shoulder surgery.

Exclusion Criteria:

• Allergy to local anesthetics.
• Infection at the injection site.
• Coagulation disorders.
• Respiratory diseases ( Acute or Chronic) or Chest trauma.
• Multiple traumatized patients.
• Phrenic nerve injury
• Heart failure, Cardiomyopathy.
• Severe organ dysfunction
• Patient refusal

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Interscalene block alone; Interscalene block alone, we will inject 20 mL of 0.5 % bupivacaine plus 10 mL of 0.9 % normal saline around brachial plexus in the interscalene site under ultrasonograhy.	Other: Regional anesthesia in shoulder surgery; Comparison of the interscalene block alone versus combined with superior truncus block during shoulder surgery in diaphragmatic function
Active Comparator: Interscalene block plus Superior truncus block; We will inject 7 mL of 0.5 % bupivacaine plus 3 mL of 0.9 % normal saline ( Total amount 10 ml) around brachial plexus in the interscalene site under ultrasonograhy.; Also we will inject 13 mL of 0.5 % bupivacaine plus 7 mL of 0.9 % normal saline ( Total amount 20 ml) around Superior trunk of brachial plexus under ultrasonagraphy.	Other: Regional anesthesia in shoulder surgery; Comparison of the interscalene block alone versus combined with superior truncus block during shoulder surgery in diaphragmatic function

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Comparison between interscalene block alone versus combined with superior truncus block inproducing diaphragmatic paralysis	Assessment of diaphragmatic function by diaphragm excursion (DE) and diaphragm thickening fraction (TF) will be measured both before and 30 minutes post-block. To measure DE, patients will be placed in a supine position, a convex transducer (3.5 ~ 5 MHz) will be used to scan while the right diaphragm through the hepatic window and the left diaphragm through the splenic window, which located near the anterior-axillary line. The craniocaudal movement of the diaphragm will be documented during deep inspiration using M-mode.; Complete diaphragmatic paralysis was defined as a 75% ~ 100% reduction in DE, including the occurrence of paradoxical movement.; Partial diaphragmatic paralysis was defined as a 25% ~ 75% reduction in DE.; No diaphragmatic paralysis was indicated by a DE reduction of less than 25%. To measure TF, patients will be placed in the same position with the head of the bed at 45°degree	Assessment of diaphragmatic function by diaphragm excursion (DE) and diaphragm thickening fraction (TF) will be measured both before and 30 minutes post-block.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Evaluation of the interscalene block alone versus combined with superior truncus block during shoulder surgery on the pulmonary function	Assessment of pulmonary function by a handheld spirometer to measure forced vital capacity (FVC), forced expiratory volume ( FEV1, FEV2) with patients in an upright-seated position pre-block and 30 minutes post-block as well as 2-hours post-surgery. Spirometry will be performed three times, with the best effort recorded.	Assessment of pulmonary function by a handheld spirometer to measure forced vital capacity (FVC), forced expiratory volume ( FEV1, FEV2) with patients in an upright-seated position pre-block and 30 minutes post-block as well as 2-hours post-surgery
Evaluation of postoperative analgesic consumption	Pain will be evaluated Postoperative immediately every hour in 1st 6 hours, every 2 hours in 2nd 6 hours by Visual Analogue Scale ( VAS) by instructing the patient to point to the position on the line to indicate how much pain they are currently feeling(10).; VAS (zero) indicates no pain.; VAS ( 1, 2, 3) indicates mild pain.; VAS ( 4, 5, 6) indicates moderate pain.; VAS ( 7, 8, 9, 10) : indicates severe pain.	12 hours
Evaluation of any complications or side effects during shoulder surgery	Any local or systemic complications or side effects will be recorded every 2 hours post operative for 24 hours such as local anesthetic systemic toxicity (LAST), Horner's syndrome, hypoxia, dyspnea, pneumothorax and post-operative nausea and vomiting (PONV).	24 hours
Duration of the sensory and motor block onset, duration of the interscalene block alone versus combined with superior truncus block during shoulder surgery	Sensory block onset time will be assessed at the time from local anesthetics injection by pinprick test which will be preformed with 22-gauge short beveled needle every minute. Sensory block recovery time will be noted every hour in 1st 6 hours, every 2 hours in 2nd 6 hours till recovery of all pain sensation in all dermatomes performed by pinprick test. Motor block onset time will be assessed at the time from local anesthetics injection until complete motor block which will be assessed by absence of voluntary movement on asking the patient to elevate his arm every minute. Motor block recovery time will be noted as the time of return of voluntary movement in the arm every hour in 1st 6 hours, every 2 hours in 2nd 6 hours.	Sensory, motor block onset time every minute. Sensory, Motor block duration every hour in 1st 6 hours , every 2 hours in 2nd 6 hours

Collaborators and Investigators

• Sponsor: Sohag University
• Investigators: Principal Investigator: Sherif Salah Ismail Assistant lecturer of Anesthesia, Assistant lecturer of Anesthesia and ICU and Pain Management of Sohag University hospitals

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): April 1, 2027
• Study Completion (Estimated): June 1, 2027

Study Registration Dates

• First Submitted: December 8, 2025
• First Submitted That Met QC Criteria: January 3, 2026
• First Posted (Actual): January 14, 2026

Study Record Updates

• Last Update Posted (Actual): February 6, 2026
• Last Update Submitted That Met QC Criteria: February 4, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Anesthesia and Analgesia; Anesthesia; Anesthesia, Conduction
• Other Study ID Numbers: Soh-Med--25-11-5MD

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No