A client was admitted to the inpatient unit for depression and is prescribed a selective serotonin reuptake inhibitor (SSRI). Which sign or symptom would the nurse include in the teaching session about serotonin syndrome?

Choice A reason: A lithium level of 1.2 mEq/L is within the therapeutic range (0.6–1.5 mEq/L) for bipolar disorder. Symptoms like confusion, ataxia, polyuria, and blurred vision indicate toxicity, which occurs at higher levels, typically above 1.5 mEq/L, making this level unlikely for these severe symptoms.

Choice B reason: A lithium level of 1.4 mEq/L is at the upper end of the therapeutic range. While mild side effects may occur, severe symptoms like mental confusion, ataxia, and polyuria suggest toxicity, which typically occurs at levels above 1.5 mEq/L, ruling out this option.

Choice C reason: A lithium level of 2.3 mEq/L indicates toxicity, causing neurological symptoms (confusion, ataxia), polyuria due to nephrogenic diabetes insipidus, and blurred vision from central nervous system effects. These symptoms align with lithium toxicity, which occurs at levels above 1.5 mEq/L, making this the expected level.

Choice D reason: A lithium level of 1.8 mEq/L is slightly above therapeutic range and may cause mild toxicity symptoms, such as tremor or nausea. However, the severe symptoms described (confusion, ataxia, polyuria) are more consistent with higher toxic levels, such as 2.3 mEq/L, making this less likely.

Choice A reason: Independent atrial and ventricular beating occurs in conditions like third-degree heart block, where AV node conduction fails completely. The description lacks specific rhythm details, but the SA node firing with non-conducted beats suggests a partial conduction issue, not complete dissociation.

Choice B reason: An atrial rate of 350 bpm or greater with a slower ventricular rate suggests atrial flutter or fibrillation. However, the description of regular SA node firing with non-conducted beats points to a conduction block, not a rapid atrial rhythm, making this less likely.

Choice C reason: The SA node firing regularly with non-conducted beats describes a second-degree AV block, where some atrial impulses fail to reach the ventricles due to AV node or bundle branch issues. This matches the symptoms and is the most accurate interpretation of the rhythm.

Choice D reason: A delayed but not blocked AV node impulse describes first-degree heart block, where all beats conduct with a prolonged PR interval. The description of non-conducted beats indicates a more severe conduction issue, such as second-degree block, making this choice incorrect.