A 65-year-old male presents to the ED in respiratory distress. His past medical history includes hypertension, dyslipidemia, type 2 diabetes and osteoarthritis. He is a lifetime non-smoker and does not have a history of lung disease. His vital are: BP 110/85, HR 100, RR 30, SpO2 91% on a non-rebreather mask. Point-of-care ultrasound shows signs of left lower lobe pneumonia. Which of the following is the MOST appropriate next step?