An Observational Study on Incidence and Clinical Characteristics of Breakthrough Pain Following Brachial Plexus Block in Adult Patients With Diabetes Mellitus

Background: Diabetes mellitus is a highly prevalent chronic disease worldwide. Diabetic peripheral neuropathy is one of its common complications, which may alter peripheral nerve function and pain perception. Brachial plexus block is widely used for upper-limb surgery. Rebound-breakthrough pain is a clinically important adverse event after peripheral nerve block, which worsens postoperative recovery and increases opioid consumption. The incidence and clinical features of this pain among patients with type 2 diabetes remain unclear.

This observational study enrolls adult patients undergoing elective upper-extremity surgery with ultrasound-guided brachial plexus block. Participants are separated into two groups: patients with type 2 diabetes mellitus and patients without diabetes. All patients receive routine clinical anesthesia with 0.375% ropivacaine for brachial plexus block without any experimental intervention. Pre-operative baseline information includes demographic data, glycosylated hemoglobin, diabetic history, and sensory threshold measurement. Post-block data including pain scores, onset and recovery time of sensory-motor block, patient-controlled analgesia usage and additional analgesic consumption are recorded.

The primary objective is to calculate the incidence of postoperative breakthrough-rebound pain. Secondary objectives cover pain severity, onset and duration of breakthrough pain, and perioperative analgesic consumption. Collected data will be summarized and analyzed to describe clinical characteristics associated with breakthrough pain.