The study aims to evaluation the effects of Liposomal Bupivacaine on diaphragmatic function in patients undergoing upper limb surgery who receive Interscalene Brachial Plexus Block. A total of 120 eligible patients will be enrolled and divided into two groups: Group A will receive 20ml of 0.5% Hydrochloride Bupivacaine , while Group B will receive 10ml of 0.5% Hydrochloride Bupivacaine plus 10ml of Liposomal Bupivacaine. Assessments of diaphragmatic function, pulmonary function, and pain intensity will be performed before the block and at different time points after the block, with follow-up for adverse events. The study is scheduled to run from September 2025 to September 2026, with strict adherence to privacy protection and ethical guidelines.

Inclusion Criteria:

• Patients undergoing upper limb surgery scheduled for interscalene brachial plexus block
• Aged ≥ 18 years
• American Society of Anesthesiologists (ASA) physical status I-III

Exclusion Criteria:

• Known allergy or intolerance to amide local anesthetics
• Nerve injury in the upper limb on the surgical side
• Coagulopathy
• Used opioid medications continuously for more than 3 weeks before surgery
• History of pulmonary disease and a pulse oxygen saturation (SpO₂) < 95% (measured after 5 minutes of rest at room temperature without oxygen supplementation, using a transcutaneous pulse oximeter)
• Refuse to participate or are deemed unsuitable for this trial by the researchers

Withdrawal Criteria:

• Patients voluntarily withdrew their informed consent
• Surgery was canceled or the anesthesia method was changed due to surgical factors before interscalene brachial plexus block