A 35-year-old man is admitted to the hospital 6 hours after sustaining a deep burn injury to his right thigh and lower leg from a cooking oil splash. On examination, the burned area is charred, leathery, and painless. The skin does not blanch when pressed. He is alert and oriented. His urine output is 0.3 mL/kg/hour despite IV fluids. What is the most appropriate next step in management?