A nurse is caring for a male client who reports nausea and vomiting and is receiving IV fluid therapy. His blood urea nitrogen (BUN) is 32 mg/dL (Range 8-24 mg/dl), creatinine 1.1 mg/dL (Range 0.7-1.3 mg/dl), and hematocrit 50% (range 40-54%). Which of the following nursing interventions is appropriate?