Journal of Postgraduate Medicine Medknow Publications and Staff Society of Seth GS Medical College and KEM Hospital, Mumbai, India ISSN: 0022-3859 EISSN: 0972-2823 Vol. 48, Num. 4, 2002, pp. 327

Journal of Postgraduate Medicine, Vol. 48, Issue 4, 2002 pp. 327

Letter to the Editor

Methylene Blue as Treatment for Contrast Medium-induced Anaphylaxis

Evora PR*, Oliveira Neto AM, Duarte NM, Vicente WVA

Prodiagnóstico - São Gonçalo, Rio de Janeiro, Brazil, *Division of Experimental Surgery - Ribeirão Preto School of Medicine - University of São Paulo, Ribeirão Preto, SP, Brazil. E-mail: prbevora@keynet.com.br

Code Number: jp02108

Sir,

Nitric oxide seems to play an important pathophysiological role in modulating the systemic changes associated with anaphylaxis.¹ Considering nitric oxide to be the final mediator of vasoplegia, we have used methylene blue to treat anaphylactic shock secondary to radio-contrast material and penicillin² in three patients, with a good immediate response. We have also used the drug to treat vasoplegia in cardiac surgery.^3,4,5,6

Three patients who developed anaphylactic shock following injection of radiocontrast media during coronary angiography were treated with an intravenous bolus of methylene blue (1.5-2 mg/kg). The drug was administered to two patients after hydrocortisone (2 gm) and adrenaline (4-5 mg) failed to provide the necessary response. The third patient received methylene blue alone for the treatment of anaphylactic shock. Injection of methylene blue was associated with prompt improvement in circulatory status. It was possible for us to monitor circulatory status as the procedure was undertaken in the cardiovascular catheterisation laboratory.

Side effects in the form of nodal rhythm and chest pain were observed in one patient each. The nodal rhythm that occurred during methylene blue infusion reverted spontaneously to normal rhythm within a minute.² Another hypertensive patient, who had anaphylactic shock during CT scan, complained of chest pain during the methylene blue infusion, but as no ECG changes ensued coronary vasodilators were not employed. We stress that the physiopathology of the ECG changes (nodal rhythm) and the chest pain episode they could be attributed either to the methylene blue infusions or to the radiocontrast agent used.

Methylene blue has been successfully used in the treatment of several disorders such as sepsis, SIRS, anaphylactic shock, and for reversion of methemoglobinaemia in the dose of 1-2 mg/kg intravenously.^2-6 Although corticosteroids, adrenaline, oxygen and volume expanders have been used in the treatment of anaphylactic shock with a great deal of success, we wish to share our experience regarding the use of methylene blue so that it can be considered as a treatment option in situations where the above measures fail to elicit the desired response.

We concede that the hypothesis of nitric oxide being a mediator of anaphylaxis, on which the use of methylene blue is based, is largely unproven. In addition, there are no studies that have compared the efficacy and safety of methylene blue vis-à-vis conventional methods of management. In fact, we are not sure whether ethical considerations will permit conduct of such a study. Methylene blue has some side effects as well. However, our clinical experience reported previously^2,3,4,5 and in this communication; and the results of animal studies conducted by us (unpublished data) make us believe that methylene blue is likely to be safe and effective in the treatment of anaphylactic shock although information on both efficacy and safety needs to be generated on an ongoing basis. We have experienced seven such occasions in the last 16 years, when a patient with anaphylactic shock did not respond to the conventional methods. Our experience with methylene blue may be of use to physicians who deal with such situations.

Evora PR*, Oliveira Neto AM, Duarte NM, Vicente WVA

Prodiagnóstico - São Gonçalo, Rio de Janeiro, Brazil, *Division of Experimental Surgery - Ribeirão Preto School of Medicine - University of São Paulo, Ribeirão Preto, SP, Brazil.

E-mail: prbevora@keynet.com.br

References

1. Kaeser P, Hammann C, Luthi F, Enrico JF. Anaphylactic shock. Schweiz Rundsch Med Prax 1995;84:1307-13.
2. Evora PR, Roselino CH, Schiavetto PM. Methylene blue in anaphylactic shock. Ann Emerg Med 1997;30:240.
3. Andrade JCS, Batista Filho ML, Evora PR, Tavares JR, Buffolo E, Ribeiro EE et al. Methylene blue administration in the treatment of the vasoplegic syndrome after cardiac surgery. Rev Bras Cir Cardiovasc 1996;11:107-14.
4. Evora PR, Ribeiro PJ, Andrade JCS. Methylene blue administration in SIRS after cardiac operations. Ann Thorac Surg 1997;63:112-3.
5. Evora PR. Should methylene blue be the drug of choice to treat vasoplegias caused by cardiopulmonary bypass and anaphylactic shock? J Thorac Cardiovasc Surg 2000;119:632-4.
6. Viaro F, Dalio MB, Evora PR. Catastrophic cardiovascular adverse reactions to protamine are nitric oxide/cyclic guanosine monophosphate dependent and endothelium mediated: should methylene blue be the treatment of choice? Chest 2002;122:1061-6.

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