CJA
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Full Text (PDF)
Right arrow Submit a scholarly reply
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Sharma, D.
Right arrow Articles by Bithal, P. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sharma, D.
Right arrow Articles by Bithal, P. K.
Canadian Journal of Anesthesia 52:884-885 (2005)
© Canadian Anesthesiologists' Society, 2005

Correspondence

Methylene blue in congenital methemoglobinemia: prophylactic or on demand?

Deepak Sharma, MD, Mihir Prakash Pandia, MD and Parmod Kumar Bithal, MD

All India Institute of Medical Sciences, New Delhi, India, E-mail: mihirpandia{at}yahoo.co.in

To the Editor:

We read with interest the article "Prophylactic methylene blue in a patient with congenital methemoglobinemia".1 However, we feel the patient’s condition did not warrant prophylactic administration of methylene blue. Surgery of this patient was cancelled previously because of severe hypoxia due to respiratory depression following induction of anesthesia without preoxygenation. But oxygenation had improved following ventilation with 100% oxygen, before giving methylene blue.2 On this occasion however, the patient was preoxygenated following which, PaO2 increased from 81.3 to 543 mmHg and SaO2 from 96.2 to 99.7%. Preoxygenation itself provided an adequate margin of safety against hypoxia. Homozygotes and compound heterozygotes for cytochrome b5 reductase deficiency are cyanotic but asymptomatic even with methemoglobin levels up to 40%, and have less risk of acute deterioration after exposure to exogenous methemoglobin inducing agents.3 Symptoms of oxygen deprivation appear only as methemoglobin levels rise above 30%.4 Intravenous methylene blue is indicated only for emergency treatment of "toxic" methemoglobinemia3 and is known to cause serious adverse effects.

In our opinion, anesthetic management of congenital methemoglobinemia should target oxygenation rather than methemoglobin levels, and pharmacological intervention to decrease methemoglobin levels should be attempted only when increased methemoglobin leads to impaired oxygenation. We feel that the authors should have proceeded without prophylactic administration of methylene blue and should have administered the drug only if increased methemoglobin levels lead to desaturation. Also, the authors should have ruled out G6PD deficiency.

Recently, we managed a case of congenital methemoglobinemia with coexisting Osler-Weber-Rendu syndrome. Despite associated pulmonary arteriovenous malformations, anesthesia was successfully managed without using methylene blue.5

References

1 Baraka AS, Ayoub CM, Yazbeck-Karam V, et al. Prophylactic methylene blue in a patient with congenital methemoglobinemia. Can J Anesth 2005; 52: 258–61.[Abstract/Free Full Text]

2 Baraka AS, Ayoub CM, Kaddoum RN, Maalouli JM, Chehab IR, Hadi UM. Severe oxyhemoglobin desaturation during induction of anesthesia in a patient with congenital methemoglobinemia. Anesthesiology 2001; 95: 1296–7.[Medline]

3 Prchal JT, Gregg XT. Red cell enzymopathies. In: Hoffman R, Benz EJ, Shattil SJ, et al. (Eds). Hematology Basic Principles and Practice. Philadelphia: Churchill Livingstone; 2000: 561–76.

4 Benz EJ Jr. Hemoglobin variants associated with hemolytic anemia, altered oxygen affinity, and methemoglobinemias. In: Hoffman R, Benz EJ, Shattil SJ, et al. (Eds). Hematology Basic Principles and Practice. Philadelphia: Churchill Livingstone; 2000: 554–61.

5 Sharma D, Pandia MP, Bithal PK. Anaesthetic management of Osler-Weber-Rendu syndrome with coexisting congenital methaemoglobinaemia. Acta Anaesthesiol Scand 2005 (in press).





This Article
Right arrow Full Text (PDF)
Right arrow Submit a scholarly reply
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Sharma, D.
Right arrow Articles by Bithal, P. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sharma, D.
Right arrow Articles by Bithal, P. K.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS