Altered Mental Status in a Man with Depression

A 41-year-old man with a history of chronic back pain, depression, and alcohol abuse presents to the Emergency Department (ED) with slurred speech and confusion. He is uncooperative and is noted to have an altered mental status. A quick review of his records shows that the patient had been seen early in the morning on the same day of presentation by Psychiatry in the ED for worsening depression and suicidal ideation stemming from his chronic back pain. At that time of the morning visit to the ED, he was not considered an imminent threat to himself, and an outpatient follow-up was arranged for the following week. A look through his hospital records indicates that his back pain was previously evaluated by multiple spine surgeons and is currently being medically managed with baclofen. He was also on amitriptyline for his depression, with the thought that this medication may also help with his chronic pain.

On physical examination, the patient has a depressed mental status as noted. His blood pressure is 90/60 mm Hg and his heart rate is 120 bpm. He has normal respirations at a rate of 12 breaths/min, an oxygen saturation of 97% while breathing room air, and a rectally obtained temperature of 102.5°F (39.2°C). He is noted to have dry skin and bilaterally dilated pupils, at 6mm, which are minimally reactive to light. The cardiovascular and respiratory examinations are significant only for tachycardia. There is no abdominal distention and no evidence of trauma to the body. A broad panel of laboratory investigations, including a complete blood count, chemistry panel, coagulation profile, and acetaminophen and aspirin levels, is ordered. The patient undergoes orotracheal intubation for protection of his airway, given his mental status; an urgent computed tomography (CT) scan of his head and an electrocardiogram (ECG; Image 1) are ordered.

What is the diagnosis?

What is the diagnosis?
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Look closely at the QRS and QT intervals and at lead aVR.