A nurse is caring for a client receiving a hemodialysis treatment. Which of the following complications should the nurse recognize when the client becomes restless and reports nausea and headache?

A. Air embolism: This may cause chest pain, dyspnea, tachycardia, and hypotension. While serious, it usually presents with more dramatic respiratory and cardiovascular symptoms, not primarily neurological ones. B. Septic shock: Characterized by fever, hypotension, tachycardia, and signs of systemic infection. Nausea and headache may occur, but restlessness and neurologic symptoms alone do not strongly suggest sepsis. C. Disequilibrium syndrome: This occurs due to rapid fluid and solute shifts during initial hemodialysis treatments. Symptoms include headache, nausea, restlessness, confusion, and potentially seizures due to cerebral edema. D. Acute hemolysis: Can occur from exposure to contaminated dialysate or overheated solutions. Signs include back pain, chest pain, and dark-colored urine, rather than primarily headache and nausea.