A Closed Glottis After Shoulder Arthroscopy: A Rare Airway Complication of Interscalene Block Causing Postoperative Respiratory Failure

Interscalene brachial plexus block (ISB) is commonly used for shoulder surgery and is associated with predictable complications such as phrenic nerve palsy due to its proximity to adjacent neural structures. While the spread of local anesthetic may involve the recurrent laryngeal nerve, resulting in vocal cord dysfunction, which is uncommon, progression to bilateral vocal cord paralysis, causing acute airway obstruction, is exceedingly rare. A 74-year-old obese female underwent elective outpatient right shoulder arthroscopy under ultrasound-guided interscalene block with bupivacaine. Within hours postoperatively, she developed progressive respiratory distress. Despite high-flow oxygen and bag-valve-mask ventilation, oxygen saturation declined into the 60s with marked resistance to ventilation. Emergent intubation resulted in immediate improvement. Point-of-care ultrasound demonstrated diffuse B-lines without right heart strain, and imaging confirmed pulmonary edema. Workup did not reveal a primary pulmonary or obstructive cardiac etiology; however, troponin elevation consistent with type 2 myocardial infarction was identified. The patient improved rapidly with ventilatory support and diuresis, was extubated within 48 hours, and was discharged without recurrence. This case demonstrates a rare complication of ISB involving sequential spread of local anesthetic, potentially facilitated by arthroscopic fluid extravasation, leading to phrenic nerve involvement and bilateral recurrent laryngeal nerve dysfunction. Resultant airway obstruction caused negative pressure pulmonary edema and secondary demand ischemia. Resistance to ventilation and refractory hypoxemia after ISB should raise concern for upper airway obstruction. Early airway management is critical to improve outcomes.