A 68-year-old man with COPD presents to the emergency department with acute onset of severe mydriasis, cycloplegia, tachycardia (HR 128/min), dry mouth, and confusion. He had been using ipratropium bromide inhaler 4 times daily for the past 3 days following a respiratory exacerbation. On examination, his pupils are 8 mm and non-reactive to light. What is the most appropriate immediate next step in management?