Medicine>>>>>Allergy and Immunology
Question 6#

A 16-year-old woman develops weakness, wheezing, and shortness of breath 5 minutes after receiving intramuscular ceftriaxone for gonorrhea. She is on no other medications. On examination, she is anxious and in respiratory distress. BP is 80/50, HR is 142, and RR is 40. She has large hives on her chest, and her tongue is edematous. She has both wheezing and stridor.

Which of the following is most important immediate treatment? 

A) Intramuscular or intravenous epinephrine 0.3 mg STAT
B) Intravenous epinephrine 1 mg IV push
C) Intravenous methylprednisolone 100 mg and diphenhydramine 50 mg
D) Intravenous normal saline 1 L over 20 minutes
E) Intravenous dopamine titrated to a mean arterial pressure of 60 mm

Correct Answer is A


This patient has severe anaphylaxis (anaphylactic shock) and immediate treatment may be life-saving. Epinephrine is the cornerstone of treatment. For mild to moderate cases, subcutaneous epinephrine is recommended. If the patient is in shock, cutaneous perfusion may be compromised and IM or IV epinephrine is preferable. The proper dose is 0.3 mg (0.3 mL of the 1:1000 solution, diluted if given intravenously), repeated if necessary at 5- to 10-minute intervals. The 1-mg container of epinephrine, available on the “crash cart,” is reserved for cardiac arrest. Antihistamines such as diphenhydramine can be used for mild urticaria but are ineffective in anaphylaxis. Corticosteroids are not helpful acutely; they are given to prevent the “second wave” of mediator release that can occur 8 to12 hours after the initial event. Intravenous saline is important in the management of shock, but will not relieve the laryngospasm and bronchospasm. Epinephrine will elevate the blood pressure more promptly than saline. Dopamine is less effective than epinephrine in anaphylactic shock; in addition it takes longer to uptitrate the infusion rate than it does to give every-5-minute boluses of epinephrine.