Which statement about epinephrine's respiratory effect is true?

Which statement about epinephrine's respiratory effect is true?

• A. It does not affect the airways.
• B. It causes bronchodilation.
• C. It causes bronchoconstriction in all patients.
• D. It only affects bronchioles in adults.

Answer: (B)

Epinephrine opens the airways by stimulating beta-2 receptors on bronchial smooth muscle, which causes the muscle to relax and the airways to dilate. This bronchodilation reduces airway resistance and helps relieve bronchospasm seen in allergic reactions and asthma. It may also reduce swelling through alpha-1–mediated vasoconstriction, but the key respiratory effect is bronchodilation from beta-2 stimulation. That’s why the true statement is that epinephrine causes bronchodilation. The other options don’t fit because epinephrine does affect the airways and relaxes them, bronchoconstriction is not its effect, and its bronchodilatory action is not limited to adults.

Epinephrine opens the airways by stimulating beta-2 receptors on bronchial smooth muscle, which causes the muscle to relax and the airways to dilate. This bronchodilation reduces airway resistance and helps relieve bronchospasm seen in allergic reactions and asthma. It may also reduce swelling through alpha-1–mediated vasoconstriction, but the key respiratory effect is bronchodilation from beta-2 stimulation. That’s why the true statement is that epinephrine causes bronchodilation. The other options don’t fit because epinephrine does affect the airways and relaxes them, bronchoconstriction is not its effect, and its bronchodilatory action is not limited to adults.