Soru

A 19-year-old male college student is transported to the emergency department after suddenly developing severe difficulty breathing and facial swelling while at a local seafood restaurant. He states that his throat feels tight. He has no known past medical history and takes no daily medications. On presentation, the patient is visibly anxious and using accessory muscles of respiration. Temperature is $37.0^\circ$ C ($98.6^\circ$ F), blood pressure is $86/50$ mmHg, pulse is $128$/min, respirations are $28$/min, and oxygen saturation is $94\%$ on room air. Physical examination reveals audible stridor, diffuse bilateral wheezing, and raised, erythematous plaques on his anterior chest. Which of the following is the most appropriate initial step in the management of this patient?