Importance of Vigilant Monitoring After Continuous Nerve Block: Lessons From a Case Report

INTRODUCTION

Continuous peripheral nerve blocks are used extensively for postoperative pain management. Although nerve blocks achieve good pain control, pain physicians should be aware that uncontrolled pain, despite an effective block in the target areas, or pain in nonanesthetized areas can be an early sign of ischemia. We report a case of iatrogenic injury to the axillary artery during shoulder surgery in a patient who had continuous supraclavicular block and demonstrate how vigilant monitoring helped us diagnose and manage the upper extremity ischemia.

CASE REPORT

A 58-year-old female with a history of stable hypertension presented for revision surgery of her right total shoulder. She was premedicated with 1 mg midazolam and around noon on the day of the surgery received a supraclavicular nerve block with a catheter for postoperative pain management. The nerve block was performed under ultrasound guidance and strict aseptic precautions without any adverse events. A total of 20 mL of 0.75% ropivacaine was injected, and the block was confirmed with sensory and motor testing. Following the nerve block, the patient underwent the revision shoulder surgery in the sitting position under general anesthesia. The surgery lasted 260 minutes and was associated with 300 mL blood loss. Intraoperatively, the patient had stable hemodynamics, and the surgeon reported a difficult, yet uncomplicated procedure. Postoperatively, the supraclavicular catheter was connected to an infusion pump containing 0.2% ropivacaine. The infusion was set up as patient-controlled analgesia to a basal rate of 8 mL per hour and patient demand dose of 12 mL every 60 minutes as needed. The patient was comfortable in the postanesthesia care unit (PACU), did not need any supplemental analgesia, and was transferred to the regular nursing floor around 7 pm. Staff performed routine monitoring according to hospital policy.

At 4 am, almost 9 hours after the end of surgery, the patient complained of pain along the medial side of her forearm. She was in tears and described the sensation as “My right hand feels like balloons, and the movement is unnatural. I can move my hands, but they are numb.” She had no pain over the surgical site. On physical examination, the arm was slightly dusky, capillary refill was brisk, radial and brachial pulses were palpable, and the hand was warm. After receiving a top-up dose through the supraclavicular catheter with 15 cc of 0.5% ropivacaine, the patient reported satisfactory pain relief. At this point, neurovascular checks were performed hourly to exclude any progressive ischemic injury.

At the 9 am examination, the hand was cyanosed and the pulses were weak. The patient reported increasing pain in the hand and forearm. Emergency angiography of the right upper limb showed a 3-cm segment of occlusion in the axillary artery adjacent to the shoulder joint with reconstitution at the level of the most distal part of the circumflex humeral artery. Immediate exploration of the right axillary artery confirmed a partial occlusion. Vascular surgeons repaired the occlusion via a subclavian artery-to-brachial artery bypass using a saphenous venous graft. Pulses in the right upper limb returned. Postoperatively, the patient recovered well and gained full function of the right upper limb. She was discharged home on postoperative day 4 with full neurological and functional recovery.