A nurse is caring for a client following his first hemodialysis treatment. The client reports a headache, nausea, and restlessness. The nurse should identify these findings as manifestations of which of the following complications?

Rationale: A. Peritonitis is incorrect because peritonitis occurs in peritoneal dialysis, not hemodialysis, and typically presents with abdominal pain, cloudy effluent, and fever rather than headache, nausea, and restlessness. B. Septicemia is incorrect because sepsis is associated with fever, chills, hypotension, and general malaise, often with positive blood cultures. While serious, it is less likely immediately following the first hemodialysis session without other signs of infection. C. Air embolism is incorrect because an air embolism would present with sudden dyspnea, chest pain, hypotension, cyanosis, or neurological changes. Headache and nausea alone are not typical early signs of air embolism. D. Dialysis disequilibrium is correct because it is a complication that occurs most commonly after the first hemodialysis session or when dialysis is aggressive. Rapid removal of solutes from the blood causes a fluid and osmotic shift in the brain, leading to headache, nausea, restlessness, and sometimes vomiting or confusion. It is usually self-limiting but requires slower dialysis in future treatments and close monitoring.