Soru

A 68-year-old man comes to the emergency department due to a 3-day history of worsening shortness of breath, increased cough, and a change in sputum color from clear to yellow-green. He has a history of severe chronic obstructive pulmonary disease (COPD) and ischemic cardiomyopathy with a left ventricular ejection fraction of 35%. His home medications include an albuterol inhaler, tiotropium, lisinopril, and carvedilol.

On presentation, his temperature is $38.0^\circ C$ ($100.4^\circ F$), blood pressure is 138/86 mm Hg, pulse is 98/min, and respirations are 24/min. Pulse oximetry is 92% on room air. Physical examination reveals a barrel chest, prolonged expiratory phase, and diffuse bilateral expiratory wheezes without crackles. Jugular venous pressure is 7 cm $H_2O$. There is trace bilateral lower extremity edema, which the patient states is his baseline.

Laboratory results show:
Leukocyte count: $11,500/mm^3$
B-type natriuretic peptide: 150 pg/mL

Arterial blood gas (room air):
pH: 7.36
$PaCO_2$: 52 mm Hg
$PaO_2$: 64 mm Hg
Calculated $HCO_3^-$: 28 mEq/L

A chest radiograph shows hyperinflated lungs with flattened diaphragms and no focal consolidations or pleural effusions. He is started on supplemental oxygen, nebulized albuterol and ipratropium, and systemic glucocorticoids.

Which of the following is the most appropriate additional step in management?