According to the version #7 (2010) ACR Manual on Contrast Media, the following regimens are recommended for premedication of patients at risk for developing contrast reaction.
Elective Premedication
- Prednisolone: 50 mg PO at 13 hours, 7 hours and 1 hour before contrast media injection, PLUS Diphenhydramine 50 mg IV, IM or PO 1 hour before contrast medium OR
- Methylprednisolone 32 mg PO 12 hours and 2 hours before contrast media injection. An anti-histamine (as in option 1) can be added. If unable to take oral medication, use hydrocortisone 200 mg IV instead
Emergency Premedication
- Methylprednisolone 40 mg or hydrocortisone 200 mg IV every 4 hours until contrast study required PLUS Diphenhydramine 50 mg IV 1 hour prior to contrast injection OR
- Dexamethasone 7.5 mg or betamethasone 6 mg IV every 4 hours until contrast study PLUS diphenhydramine 50 mg IV 1 hour prior to contrast injection OR
- Omit steroid entirely and give diphenhydramine 50 mg IV
"IV steroids have not been shown to be effective when administered less than 4 to 6 hours prior to contrast injection."
Reference:
ACR Manual on Contrast Media (7th version, 2010)
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2 comments:
It's been the little secret of radiology that these pre-treatment regimens are essentially useless, as 1) The likelihood of a second contrast reaction is 8%-25% (this doesn't even address the fact that these reactions may have more to do with stress/anxiety) and 2) Steroid pre-treatment may only be effective for minor reactions (does not protect against severe reactions). This is useless medical treatment at best and dangerous at its worst, because it gives a false sense of security.
It persists, however, for medicolegal reasons: "Doctor, you knew the patient was at a higher risk for a contrast reaction, and you didn't adhere to the standard of care?" will say the friendly lawyer. Another reason we residents love it is because the standard 13-hour treatment pushes the study onto someone else's shift :)
The ED literature has woken up to this (see Schabelman E, Witting M. The relationship of radiocontrast, iodine, and seafood allergies: a medical myth exposed. J Emerg Med. 2010 Nov;39(5):701-7.). They recommend: "Do not delay emergent studies for steroid premedication. Only lengthy 12-h premedication protocols have shown any effect on reaction rates, and this small benefit was manifested primarily by decreasing minor reactions. No steroid protocol has shown a significant benefit in decreasing severe or fatal reactions."
Alergic reaction with contrast are due to histamin release from the mast cells and basophil cells. So, the pre-medication and treatment should include H1 and H2 blockers + shortacting or long acting steroids is the treatment of choice.
Dr Sushma Saroa,
Anaesthesiologist,
Department of Radiology,
Sir Ganga Ram Hospital(SGRH)
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