A 15-year-old girl with well-controlled asthma presents with a 1-week history of cough, nasal congestion, and a burning sensation in her chest. She notes that although she has taken her albuterol inhaler more than usual, her wheezing is not relieved. She is afebrile, with a pulse oximetry of 92%. She is in moderate respiratory distress with intercostal retractions. Which of the following is the most appropriate next step in management?
a) Intramuscular epinephrine
b) Continuous albuterol nebulization
c) Systemic corticosteroids
d) Levalbuterol inhalation