The nurse reviews the laboratory results of several clients. Which finding should the nurse report to the health care provider immediately?

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Narrow therapeutic index medications have a higher chance of producing adverse effects due to a very small difference between therapeutic and toxic levels. These medications require close monitoring of serum drug levels for adequate, but not toxic, dosing. Clients should also be monitored for signs of toxicity, which are specific to each medication. Phenytoin (Dilantin) is an antiseizure medication with a therapeutic index of 10-20 mcg/mL (40-79 mcmol/L) (Option A). Tube feedings decrease phenytoin absorption, which reduces serum drug concentrations and may precipitate seizures. The nurse should pause tube feedings for 1-2 hours before and after phenytoin administration to ensure adequate absorption. Phenytoin toxicity produces nystagmus, dysarthria, ataxia, and encephalopathy. (Option B) A heart rate of 62/min is expected in a client taking digoxin (therapeutic index 0.5-2.0 ng/mL [0.6-2.6 nmol/L]). Digoxin toxicity produces gastrointestinal symptoms (nausea, vomiting, diarrhea), bradycardia, and visual disturbances (blurred vision, yellow-green halos). (Option C) The therapeutic INR for a client with a mechanical heart valve is 2.5-3.5. (Option D) Anorexia is a common side effect of lithium (therapeutic index 0.6-1.2 mEq/L [0.6-1.2 mmol/L]). Lithium toxicity produces nausea, vomiting, ataxia, and tremors. Educational objective: Tube feedings decrease phenytoin (Dilantin) absorption, which reduces serum drug concentrations (therapeutic index 10-20 mcg/mL [40-79 mcmol/L]) and may precipitate seizures. The nurse should pause tube feedings for 1-2 hours before and after phenytoin administration to ensure adequate absorption.

The Nurse Reviews the Laboratory Results of Several Clients