Review Question - QID 212381

A 25-year-old man is brought to the emergency department by his fiancée for altered mental status. She states that they got in a fight that morning. She later got a text from him at work that said he was going to kill himself. She rushed back home and found him unconscious on the living room floor surrounded by his prescription pill bottles. The patient is sedated but conscious and states that he thinks he swallowed “a bunch of pills” about 2 hours ago. He also complains of nausea. The patient’s medical history is significant for bipolar disorder and chronic back pain from a motor vehicle accident. He takes lithium and oxycodone. The patient’s temperature is 99°F (37.2°C), blood pressure is 130/78 mmHg, pulse is 102/min, and respirations are 17/min with an oxygen saturation of 97% on room air. On physical exam, the patient is drowsy, and his speech is slurred, but he is fully oriented. He has horizontal nystagmus, is diffusely hyperreflexic, and has a mild tremor. His initial electrocardiogram shows sinus tachycardia. Labs are obtained, as shown below:

Serum:
Na: 143 mEq/L
K+: 4.3 mEq/L
Cl-: 104 mEq/L
HCO3-: 24 mEq/L
BUN: 18 mg/dL
Creatinine: 1.5 mg/dL
Glucose: 75 mg/dL
Lithium level: 6.8 mEq/L (normal 0.6 mEq/L – 1.2 mEq/L)

An intravenous bolus of 1 liter normal saline is given. Which of the following is the next step in management?