A 62-year-old female patient is brought to the emergency department after collapsing at a family gathering. Family members report that she has a history of hypertension and diabetes, and she has been complaining of severe dizziness and visual disturbances for the past few days. Upon assessment, the patient is found to have a blood pressure of 80/50 mmHg, a heart rate of 125 beats per minute, and she is semi-conscious with a Glasgow Coma Scale score of 12.
What is the most appropriate immediate nursing intervention?