Lactulose was prescribed two days ago for a client who was recently diagnosed with hepatic encephalopathy. The client is confused and experiencing frequent loose stools. Laboratory findings show an elevated serum ammonia (NH) level of 220 μg/dL (157.1 μmol/dL). Which action should the nurse take? Reference Range: Ammonia [10 to 80 μg/dL (6 to 47 μmol/L)]