A Client Admitted to the Cardiac Care Unit with Markedly

A client admitted to the cardiac care unit with markedly elevated blood pressure and heart failure is receiving a continuous infusion of nitroprusside.  Thirty minutes later, the client appears pale with cold, clammy skin and reports being lightheaded.  Which is the priority nursing action?

A) Auscultate the client's lungs
B) Check the client's capillary refill
C) Measure the client's blood pressure
D) Review the client's electrocardiogram (ECG)