Comparison Low-volume Versus Standard-volume Ultrasound-guided Bilateral Intermediate Cervical Plexus Block

Comparison Between Low-volume Versus Standard-volume Ultrasound-guided Bilateral Intermediate Cervical Plexus Block for Patients Undergoing Thyroidectomy: A Randomized Controlled Trial.

Thyroidectomy is commonly associated with mild-to-moderate postoperative pain that may affect respiratory function and recovery. Bilateral intermediate cervical plexus block provides effective analgesia, but larger local anesthetic volumes may increase phrenic nerve spread and diaphragmatic dysfunction. Low-volume ultrasound-guided block may provide adequate analgesia while better preserving diaphragmatic function and postoperative respiratory performance

Thyroidectomy requires effective perioperative analgesia to facilitate swallowing, coughing, deep breathing, and early mobilization. Bilateral intermediate cervical plexus block improves postoperative pain control and reduces opioid requirements, while ultrasound guidance enhances safety and accuracy. However, larger local anesthetic volumes may increase phrenic nerve involvement and diaphragmatic impairment. Ultrasound assessment of diaphragmatic excursion and thickening fraction provides objective evaluation of respiratory function. Low-volume block may preserve diaphragmatic function while maintaining satisfactory analgesic efficacy

Inclusion Criteria:

• Adult patients aged between 18 and 65 years.
• Patients scheduled for elective thyroidectomy under general anesthesia.
• American Society of Anesthesiologists (ASA) physical status I-II.
• Both sexes will be included.
• Patients able to understand the study protocol and provide written informed consent.

Exclusion Criteria:

• Patient refusal.
• Other endocrine diseases (as uncontrolled diabetes mellitus, adrenal disorders, pituitary disorders)
• Known allergy or hypersensitivity to local anesthetics.
• Coagulopathy or ongoing anticoagulant therapy contraindicating regional anesthesia.
• Local infection at the site of needle insertion.
• Preexisting diaphragmatic dysfunction or phrenic nerve palsy.
• Significant chronic respiratory disease affecting pulmonary function (e.g., severe COPD, restrictive lung disease, uncontrolled asthma).
• Morbid obesity (BMI ≥ 35 kg/m²).
• Psychiatric or neurological diseases affecting respiratory muscles.
• Previous neck surgery or anatomical deformity interfering with cervical plexus --block performance or diaphragmatic ultrasound assessment.
• Pregnancy..