Toxic Epidermal Necrolysis (TEN)

A 35-year-old woman with newly diagnosed seizure disorder presents to the emergency department with fever, malaise, and widespread dusky erythematous macules that coalesce into atypical targetoid lesions. Nikolsky's sign is positive. Mucosal involvement with hemorrhagic crusted lips and oral erosions is noted. Full-thickness epidermal necrosis is confirmed on biopsy, with estimated epidermal detachment involving 45% of body surface area. The patient was started on carbamazepine 10 days ago. The most appropriate immediate management strategy marked **A** in the diagram includes which of the following as the SINGLE MOST CRITICAL INTERVENTION?