A 62-year-old man with hypertension presents to the emergency department 2.5 hours after sudden onset of right-sided weakness and speech difficulty. Non-contrast CT head is normal. Blood pressure is 172/98 mmHg. The structure marked **B** in the diagram (IV Alteplase / Tenecteplase) is being considered for immediate administration. Which of the following is the MOST appropriate next step before administering the thrombolytic agent?