Emergency physicians dispel common beliefs about contrast allergies, antibiotics in nasal packing, tap water as an irrigation solution, and herniation after lumbar puncture

1. Contrast Allergies: Stop the Crustacean Bashing

The short message is, “Iodine is not an allergen!”¹

There are many theories about what causes “allergic-like” reactions from contrast media. However, we can stop asking about shellfish and strawberry allergies as iodine content has nothing to do with these reactions. As a matter of fact, if we are worried about iodine, we’re asking the wrong questions. The iodine content of shrimp is 1,000 mcg/kg, but chicken contains a whopping 1,248 mcg/kg. Perhaps we should have been asking about chicken allergies instead of shellfish.

The fact is that those with seafood allergies are at the same low risk for contrast reactions as those with other food allergies and asthma. In addition, only 7 to 17 percent of those with prior contrast reactions are at a risk of recurrence.¹ That’s likely much less than most of us would have thought.

A much more plausible explanation for contrast reactions seems obvious when reviewing the evolution of intravenous contrast materials. Data collected from 1985 to 1999 reflected an adverse reaction rate of 6 to 8 percent with ionic (high-osmolar) contrast use, compared with 0.2 percent with exclusive nonionic (low-osmolar) contrast use.² It stands to reason that most patients reporting a contrast reaction in the distant past experienced a reaction due to ionic contrast.

2. Lack of Backing for Antibiotics and Nasal Packing

It’s socially unacceptable to pick your nose, and it’s medically unnecessary to use antibiotics when packing one.

Although it’s a small study, we probably don’t need large numbers to disprove something that never had proof to begin with.

Nasal packing for spontaneous epistaxis, most with Merocel and some with zinc paste and Foley catheters, was utilized. In this prospective observational series, 78 were treated with amoxicillin/clavulanate and 76 without antibiotics. All patients were observed for otitis media, sinusitis, toxic shock syndrome, and any other infectious complication.³

No patients in either group developed an infectious complication. Particularly with close follow-up, antibiotics appear to be unnecessary.

3. Wounds: The Magic Cleanser

Tap water—and lots of it—is likely the best irrigation solution. In this meta-analysis of 11 studies, tap water, distilled water, cooled boiled water, and normal saline were evaluated. The studies included wounds in pediatrics and adults. Here is the breakdown:

• open fractures: one trial
• surgical wounds: four trials
• chronic wounds: one trial
• lacerations: five trials

In the laceration trials, tap water was compared to saline, and the relative risk of infection was 0.63.4 Thus, if tap water was utilized, infection was less likely than with saline irrigation.