Question

A 68-year-old man is brought to the emergency department by his son following two days of progressively worsening breathlessness. The patient describes a new onset of coughing that yields thick, yellowish mucus. He has a known history of severe chronic obstructive pulmonary disease (COPD), hypertension, and a myocardial infarction three years ago. His daily medications include an inhaled long-acting muscarinic antagonist, as-needed inhaled short-acting beta-agonists, and low-dose aspirin.

Vital signs show a temperature of 37.6°C (99.7°F), blood pressure of 145/88 mmHg, pulse of 112/min, and respirations of 26/min. Pulse oximetry reveals an oxygen saturation of 87% while breathing ambient air.

On physical examination, the patient appears visibly anxious and is using accessory muscles of respiration. Assessment of the neck shows a jugular venous pressure of 9 cm $H_2O$. Auscultation of the chest reveals widespread expiratory wheezes and a significantly prolonged expiratory phase, with no audible crackles. Cardiac examination shows a regular rhythm with no murmurs. Trace pitting edema is noted in both lower extremities.

Laboratory analysis reveals:
Leukocyte count: 11,200/mm³
Thyroid-stimulating hormone (TSH): 0.2 $\mu U/mL$ (normal: 0.4–4.0 $\mu U/mL$)
Free T4: 1.1 ng/dL (normal: 0.9–1.7 ng/dL)
Total T3: 55 ng/dL (normal: 80–200 ng/dL)

An arterial blood gas sample obtained on room air demonstrates the following values:
pH: 7.27
$PaCO_2$: 65 mmHg
$PaO_2$: 54 mmHg
$HCO_3^-$: 29 mEq/L

A portable chest radiograph displays hyperlucency of the lung fields and flattened hemidiaphragms, with no evidence of focal consolidation or vascular congestion.

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