Correct Answer: A

Rationale: In a client with a plasma lithium level of 2.1 mEq/L, immediate gastric lavage is appropriate for severe toxicity. Gastric lavage can help lower the client's lithium level by removing the unabsorbed lithium from the stomach.

Correct Answer: B

Rationale: Allopurinol can increase the risk of kidney stones as a side effect. To prevent this adverse effect, it is essential for the client to increase their fluid intake. Adequate hydration can help in preventing the formation of kidney stones by keeping urine dilute and flushing out substances that can lead to stone formation.

Correct Answer: C

Rationale: Clients prescribed with Captopril, an ACE inhibitor, are at risk of developing a persistent cough as a common adverse effect. It is essential for the client to inform their healthcare provider promptly if this side effect occurs to evaluate the need for a medication change or adjustment.

Correct Answer: D

Rationale: The correct answer is D: Headache. Headache during desmopressin therapy can indicate water intoxication, which is a potential adverse effect. Desmopressin is a medication used to treat Diabetes Insipidus by reducing excessive urination and thirst. Monitoring for headaches is crucial as it can signal decreased sodium levels due to water retention, leading to water intoxication, which is a serious concern. Hypovolemia, hypercalcemia, and agitation are not typically associated with desmopressin therapy for Diabetes Insipidus.

Correct Answer: B

Rationale: Dopamine, when administered at a low dose, acts on beta1 receptors in the heart, leading to increased myocardial contractility. This positive inotropic effect results in improved cardiac output, which is beneficial for a client with severe heart failure. Dopamine does not typically cause lowered heart rate, decreased conduction through the AV node, or vasoconstriction of renal blood vessels at low doses.