Anaphylaxis is a fulminant, unexpected, immunoglobulin E-mediated allergic reaction that can be triggered by multiple agents. Common causative agents include neuromuscular blocking drugs, latex, antibiotics, colloids, hypnotics, and opioids. Fentanyl citrate, however, is an extremely unusual cause of anaphylaxis. Pulmonary edema, although uncommon in anaphylaxis, can be a prominent feature, as was in one of the patient. An adverse drug reaction is a noxious or unintended reaction to a drug that is administered in standard doses by the proper route for the purpose of prophylaxis, diagnosis, or treatment. Reactions are classified into two major subtypes: type A, which are dose dependent and predictable; and type B, which are not dose dependent and unpredictable. Unpredictable reactions include immune (allergic) or no immune drug hypersensitivity reactions and are related to genetic susceptibilities or undefined mechanisms (formally called idiosyncratic and intolerance reactions). A drug allergy is always associated with an immune mechanism for which evidence of drug-specific antibodies or activated T lymphocytes can be shown. In the last few years, many novel drugs have entered clinical practice (i.e., biologic agents) generating novel patterns of drug hypersensitivity reactions. As old drugs continue to be used, new clinical and biologic techniques enable improvement in the diagnosis of these reactions.

The supraclavicular approach was first put into clinical practice in 1965 by Yoffa and is an underused method for gaining central access. It offers several advantages over the conventional infraclavicular approach to the subclavian vein. At the insertion site, the subclavian vein is closer to the skin, and the right-sided approach offers a straighter path into the subclavian vein. Also, this site is often more accessible during CPR and surgical procedures. In patients who are obese, this anatomic area is less distorted and in patient with congestive heart failure and cervical spine instability repositioning is not required.