Review Question - QID 109441

A 57-year-old man presents to the emergency department with dizziness and an episode of fainting that occurred when he stood up from using the bathroom. Since then, he has felt generally uncomfortable and uneasy. The patient has a medical history of obesity, and his current medications include atorvastatin, aspirin, and ibuprofen. He has not visited a physician in over 3 years and is notably non-compliant with his medications. The patient's lab values are ordered and the results are shown below:

Serum:
Na+: 137 mEq/L
K+: 3.6 mEq/L
Cl-: 100 mEq/L
HCO3-: 24 mEq/L
Urea nitrogen: 15 mg/dL
Glucose: 110 mg/dL
Creatinine: 1.2 mg/dL
Ca2+: 9.9 mg/dL

An ECG is ordered as seen in Figure A. His temperature is 99.5°F (37.5°C), blood pressure is 100/65 mmHg, pulse is 80/min, respirations are 11/min, and oxygen saturation is 96% on room air. A physical exam reveals a middle-aged man who appears uncomfortable. The pulmonary exam is notable for mild bilateral crackles. A cardiac exam is notable for a rapid rate and thready distal pulses. A neurological exam is within normal limits. Which of the following is the most appropriate next step in management?