MSFinals-6578
A 73-year-old man is undergoing an elective transurethral resection of prostate (TURP) for benign prostatic hyperplasia with spinal anaesthesia. After 40 minutes into the procedure, he complains of headache and visual disturbances. A venous blood gas analysis is ordered, and the results show severe hyponatremia. What could be the reason for this presentation?