Alprazolam withdrawal presenting as delirium after cardiac surgery

Abstract

A 4%year-old white man experienced delirium after coronary revascularization. The patient had had increasing frequency of exertional angina over a 4-month period. His past medical history included an uncomplicated inferior wal1 myocardial infarction (MI) 2 years prior to admission for which he had been treated with diltiazem, 60 mg, four times daily, atenolol, 50 mg, twice daily, and isosorbide dinitrate, 30 mg, four times daily. He also quit smoking at that time. At the time of this admission, he was exercising regularly and appeared to be an exceptionally fit, yet anxious individual. He weighed 76 kg and was 178 cm tal], had a normal physical examination, and had no other medical conditions or cardiac risk factors. He reported an allergy to penicillin, minimal alcohol use, and no recreational drug use. Cardiac catheterization showed lesions in the left anterior descending, total occlusion of the distal circumflex, and total occlusion of the posterior descending and posterior lateral right coronary systems. He desired the operation and was scheduled for coronary revascularization involving three distal grafts. Premedication consisted of 2 mg of lorazepam, orally, the night prior to surgery, nifedipine, 30 mg, propranolol, 30 mg, isosorbide dinitrate, 30 mg, morphine, 5 mg, intramuscularly (IM), and an additiona12 mg of lorazepam the morning of operation. On arrival in the operating room, the patient appeared drowsy, yet claimed to be fully alert. Blood pressure (BP) varied between 110170 and 80/40 mm Hg with a heart rate (HR) of 55 beats/min, and arterial oxygen saturation was 97% by pulse oximeter. Invasive monitors were placed without incident during which time an additional 3 mg of lorazepam was given for sedation. Pulmonary artery pressure (PAP), pulmonary capillaty wedge pressure (PCWP), and cardiac output (CO) were 26/15 mm Hg, 12 mm Hg, and 5.6 Umin, respectively. Mixed venous oxygen saturation was 81% at the time of the pulmonary artery catheter insertion, and increased to 91% with intubation, after anesthesia was uneventfully induced with 1,000 ug of fentanyl, 4 mg of midazolam, and 8 mg of vecuronium. Nitroglycerin, 0.5 &kg/min, was given intravenously prior to and during induction. One unit of blood was phlebotomized at that