A 28-year-old female is brought to the emergency department 90 minutes after sustaining a scald burn from hot cooking oil. On examination, she has partial-thickness burns involving the anterior aspect of both lower limbs and the lower abdomen. Using the Rule of Nines, the estimated BSA is 27%. She is alert, speaking in full sentences, and has a systolic BP of 118 mmHg. What is the most appropriate immediate next step in management?