Soru

A 64-year-old man is brought to the emergency department by his family due to progressive confusion and severe shortness of breath. The family reports that he has had fever, chills, and a cough producing rust-colored sputum for the past 4 days. His medical history is significant for heart failure with preserved ejection fraction (HFpEF) and hypertension. His temperature is $39.1^\circ\text{C}$ ($102.4^\circ\text{F}$), pulse is $128\text{/min}$, respirations are $34\text{/min}$, and blood pressure is $82/48\text{ mm Hg}$. Pulse oximetry shows an oxygen saturation of $85\%$ on $15\text{ L/min}$ of oxygen via a non-rebreather mask. On physical examination, the patient is lethargic and arouses only to painful stimuli. He has marked suprasternal retractions and uses accessory muscles of respiration. Chest auscultation reveals dense crackles and egophony over the left lower lung field. The cardiovascular examination shows a rapid, regular rhythm with no jugular venous distention. Laboratory studies show a leukocyte count of $22,000/\mu\text{L}$ and a serum lactate of $7.2\text{ mmol/L}$. An arterial blood gas analysis on $15\text{ L/min}$ of supplemental oxygen reveals the following:

$pH$: $7.12$
$pCO_2$: $35\text{ mm Hg}$
$pO_2$: $54\text{ mm Hg}$
$HCO_3^-$: $11\text{ mEq/L}$

Which of the following is the most appropriate next step in the management of this patient?