Final answer:
To manage hypotension and dizziness post-spinal anesthesia, the nurse should elevate the client's legs to improve venous return and increase blood pressure, as well as consider other supportive measures.
Step-by-step explanation:
A nurse who notices a client feeling dizzy with a blood pressure of 84/54 mmHg shortly after spinal anesthesia should perform interventions to counteract the effects of hypotension, likely due to a sympathetic block from the anesthesia. The dizziness and low blood pressure suggest a state of relative hypovolemia and decreased sympathetic tone, leading to a condition similar to orthostatic hypotension. The correct action from the provided options would be B) Elevate the client's legs, as this would help to increase venous return to the heart, thereby increasing cardiac output and helping to normalize blood pressure. Other measures might include the administration of intravenous fluids to increase blood volume and the use of vasopressors, but these actions were not listed in the options provided.