On Day 25, she is discharged from the hospital, and returns to the LTC facility.
The authors’ observations
Ms. P’s delirium was a combination of her older age, non-renally adjusted sotalol, and CKD. At admission, the hospital treatment team first thought that pneumonia or antibiotic use could have caused delirium. However, Ms. P’s condition did not improve after antibiotics were stopped. In addition, several chest radiographs found no evidence of pneumonia. It is important to check for any source of infection because infection is a common source of delirium in older patients.1 Urine samples revealed no pathogens, a C. difficile test was negative, and the patient’s white blood cell counts remained within normal limits. Physicians began looking elsewhere for potential causes of Ms. P’s delirium.
Ms. P’s vital signs ruled out a temperature irregularity or hypertension as the cause of her delirium. She has a slightly low oxygen saturation when she first presented, but this quickly returned to normal with administration of oxygen, which ruled out hypoxemia. Laboratory results concluded that Ms. P’s glucose levels were within a normal range and she had no electrolyte imbalances. A head CT scan showed slight atrophy of white matter that is consistent with Ms. P’s age. The head CT scan also showed that Ms. P had no acute condition or head trauma.
In terms of organ function, Ms. P was in relatively healthy condition other than paroxysmal atrial fibrillation and CKD. Chronic kidney disease can interrupt the normal pharmacokinetics of medications. Reviewing Ms. P’s medication list, several agents could have induced delirium, including antidepressants, antipsychotics, cardiovascular medications (beta blocker/antiarrhythmic [sotalol]), and opioid analgesics such as tramadol.5 Ms. P’s condition did not improve after discontinuing fluoxetine, risperidone, or olanzapine, although haloperidol was started in their place. Ms. P scored an 8 on the Naranjo Adverse Drug Reaction Probability Scale, indicating this event was a probable adverse drug reaction.9
Identifying a cause
This was a unique case where sotalol was identified as the culprit for inducing Ms. P’s delirium, because her age and CKD are irreversible. It is important to note that antiarrhythmics can induce arrhythmias when present in high concentrations or administered without appropriate renal dose adjustments. Although Ms. P’s serum levels of sotalol were not evaluated, because of her renal impairment, it is possible that toxic levels of sotalol accumulated and lead to arrhythmias and delirium. Of note, a cardiologist was consulted to safely change Ms. P to a calcium channel blocker so she could undergo cardiac monitoring. With the addition of diltiazem and metoprolol, the patient’s delirium subsided and her arrhythmia was controlled. Once the source of Ms. P’s delirium had been identified, antipsychotics were no longer needed.
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