Emergency premeditation for CT contrast is an important step before many diagnostic exams in a large percentage of our patients.
In every patient with a reported history of allergy to iodinated contrast material, make every reasonable effort to clarify the nature and severity of the reaction in person with the patient. If the patient is not able to provide a history, obtain history from family member/NOK/POA. The ER physician should be last source of this information. It is you who will be responsible for managing an acute life threatening contrast reaction in the event this occurs, NOT the ER physician.
In every patient with a reported history of allergy to iodinated contrast material, make every reasonable effort to clarify the nature and severity of the reaction in person with the patient. If the patient is not able to provide a history, obtain history from family member/NOK/POA. The ER physician should be last source of this information. It is you who will be responsible for managing an acute life threatening contrast reaction in the event this occurs, NOT the ER physician.
If
patient has a history of a severe anaphylactic reaction following IV
iodinated contrast, IV contrast is contraindicated (not even with
premedication).*
The following are Emergency Medication Protocols set forth by the ACR. They are listed in order of DECREASING desirability.
1.
Methylprednisolone sodium succinate (Solu-Medrol®) 40 mg or
hydrocortisone sodium succinate (Solu-Cortef®) 200 mg intravenously
every 4 hours (q4h) until contrast
study required plus diphenhydramine 50 mg IV 1 hour prior to contrast
injection.
2.
Dexamethasone sodium sulfate (Decadron®) 7.5 mg or betamethasone 6.0 mg
intravenously q4h until contrast study must be done in patent with
known allergy to methylpred-nisolone,
aspirin, or non-steroidal anti-inflammatory drugs, especially if
asthmatic. Also diphenhydramine 50 mg IV 1 hour prior to contrast
injection.
3. Omit steroids entirely and give diphenhydramine 50 mg IV.
Note: For options 1 and 2, the minimum accepted emergency premedication window using IV steroids is
4 hours. This is a frequent source of contention between the ED
physician and radiologist. If contrast will be administered less than 4
hours after the IV administration of prophylactic steroids, it is
considered a fruitless exercise.
Note:
Option 3 is the least proven and therefore the least preferred. The
advantage to this method is the theoretical “immediate protection”
against severe allergy/anaphylaxis.
Utilize this sparingly and in the most emergent, uncertain and time
sensitive of situations.
*Weigh
the risks and benefits of any decision and please, if you do anything
for the patient, do no harm. You will encounter tough decisions in a
fast paced environment
during your time in the ER. If you have a complex multi-trauma patient
who is “crashing” as they are hoisted upon the CT scanner, but have a
history of anaphylaxis to IV contrast dye, the above guidelines may or
may not apply. Use your best judgment as a physician.
Maybe a non-contrast exam will suffice? If contrast will really make a
difference in the patient’s management, squirting some Benadryl into
their IV before giving contrast may offer some protection. Keep in mind
that many of the sickest patients are already
intubated and on vasopressors.
Other tips:
1)
Shellfish allergy in itself has no specific relation to, nor
predisposition for an allergy to IV contrast. If the patient is
susceptible to many allergens (pollen
and shellfish and peanuts and etc, etc, etc) and has never received IV
contrast, premedicating them is a probably a good idea.
2)
Giving IV contrast to a nursing mother is very, very unlikely to have
any ill effects for mother and baby, but mom can wait 12-24 hrs after
receiving contrast to
resume breastfeeding, mainly for “peace of mind”.
Hope that this provides some basic information on emergency premeditation for CT contrast.
Hope that this provides some basic information on emergency premeditation for CT contrast.
Good luck.
M.B.
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