Comprehensive exams for Mental Health Q 207
Tristan is on Lithium and has suffered from diarrhea and vomiting. What should the nurse in-charge do first:
A. Recognize this as a drug interaction.
B. Give the client Cogentin.
C. Reassure the client that these are common side effects of lithium therapy.
D. Hold the next dose and obtain an order for a stat serum lithium level.
Correct Answer: D. Hold the next dose and obtain an order for a stat serum lithium level
Diarrhea and vomiting are manifestations of Lithium toxicity. The next dose of lithium should be withheld and a test is done to validate the observation. Monitoring of therapeutic levels includes trough plasma levels drawn 8 to 12 hours after the last dose. The therapeutic range is 1.0 to 1.5 mEq/L for acute treatment and 0.6 to 1.2 mEq/L for chronic therapy. Monitoring should be done every 1 to 2 weeks until reaching the desired therapeutic levels. Then, check lithium levels every 2 to 3 months for six months. It is also important to monitor patients for dehydration and lower the dose when there are signs of infection, excessive sweating, or diarrhea. Toxic levels are when the drug level is more than 2 mEq/L.
Option A: The manifestations are not due to drug interaction. Lithium has a very narrow therapeutic index, and toxic levels are when the drug is above 2 mEq/L, which is very close to its therapeutic range. Lithium toxicity can cause interstitial nephritis, arrhythmia, sick sinus syndrome, hypotension, T wave abnormalities, and bradycardia. Rarely, toxicity can cause pseudotumor cerebri and seizures. Lithium toxicity has no antidote.
Option B: Cogentin is used to manage the extrapyramidal symptom side effects of antipsychotics. Benztropine is used to treat symptoms of Parkinson’s disease or involuntary movements due to the side effects of certain psychiatric drugs (antipsychotics such as chlorpromazine/haloperidol). Benztropine belongs to a class of medication called anticholinergics that work by blocking a certain natural substance (acetylcholine). This helps decrease muscle stiffness, sweating, and the production of saliva, and helps improve walking ability in people with Parkinson’s disease.
Option C: The common side effects of Lithium are fine hand tremors, nausea, polyuria, and polydipsia. Lithium can cause several adverse effects. Typically the side effects are dose-related. Treatment for lithium toxicity is primarily hydration and to stop the drug. Give hydration with normal saline, which will also enhance lithium excretion. Avoid all diuretics. If the patient has severe renal dysfunction or failure, or severely altered mental status, then start with hemodialysis. 20 to 30 mg of propranolol given 2 to 3 times per day may help reduce tremors.