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

Sohag University

Status: Begins enrollment in 1 month

Conditions: Diaphragm Issues

Treatments: Other: Regional anesthesia in shoulder surgery

Study type: Interventional

Funder types: Other

Identifiers

NCT07338630

Soh-Med--25-11-5MD

Details and patient eligibility

About

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.

Full 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.

Enrollment: 60 estimated patients

Sex: All

Ages: 20 to 65 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Diagnostic

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Triple Blind

---

60 participants in 2 patient groups

Interscalene block alone

Active Comparator group

Description:

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.

Treatment:

Other: Regional anesthesia in shoulder surgery

Interscalene block plus Superior truncus block

Active Comparator group

Description:

1. 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. 2. 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.

Treatment:

Other: Regional anesthesia in shoulder surgery