Review Question - QID 109821

A 52-year-old homeless man presents to the emergency department intoxicated. He was found passed out in a park and brought in by police. The patient's medical history and medications are not known. He was brought in 1 week ago for an intravenous drug overdose which was treated appropriately at the time. His temperature is 99.5°F (37.5°C), blood pressure is 92/58 mmHg, pulse is 120/min, respirations are 8/min, and oxygen saturation is 98% on room air. The patient is started on IV fluids and given a dose of naloxone. Basic laboratory values are seen below.

Hemoglobin: 10 g/dL
Hematocrit: 32%
Leukocyte count: 7,500/mm^3 with normal differential
Platelet count: 167,000/mm^3

Serum:
Na+: 139 mEq/L
Cl-: 100 mEq/L
K+: 5.1 mEq/L
HCO3-: 25 mEq/L
BUN: 52 mg/dL
Glucose: 99 mg/dL
Creatinine: 2.1 mg/dL
Ca2+: 10.2 mg/dL
AST: 62 U/L
ALT: 50 U/L

The patient is clinically sober 4 hours later and history and physical exam is able to be performed. The patient complains of joint pain and pain/tingling in his extremities. A cardiopulmonary exam is notable for a murmur along the left sternal border. The patient has decreased sensation in his legs bilaterally. A dermatologic exam reveals the finding in Figure A. Which of the following is the most appropriate next step in management?