Link to [[:wikitox:methaemoglobin|Methaemoglobin]]\\
Link to [[:wikitox:methaemoglobinaemia_teaching_material|Methaemoglobinaemia Teaching Material]]\\
Link to [[:wikitox:problems_for_discussion_3_methaemoglobinaemia|Problems for discussion]]

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====== Methaemoglobinaemia ======

Methaemoglobin is occasionally produced therapeutically and is probably seen more commonly from recreational amyl nitrate use. There is a wide range of drugs and chemicals that can cause the oxidative stress that transforms Fe<sup>2+</sup>  to Fe<sup>3+</sup>  causing the patient to appear cyanosed, altering the oxygen carrying capacity and turning blood to a chocolate-brown colour.

See {{:wikitox:methylene_blue_hoffman_eapcct_2007.ppt|Bob Hoffmans talk}}  [822 KB] on treatment of MetHb in G6PD deficiency\\
See {{:wikitox:methaemoglobinaemia_1.ppt|Paediatric Case report}}  [413 KB] from Jonathon Mervis, Cape Town

===== BEDSIDE MEASUREMENT OF METHAEMOGLOBIN =====

Traditonally best side tests have been based on the detection of chocolate brown blood on tissue paper such as this example of a patient with propanil poisoning.

{{:wikitox:methb_blood_propanil.png}}

A refinement and validation of this observation using a color chart has been published: Shihana F, et al. A simple quantitative bedside test to determine methemoglobin. //Ann Emerg Med// 2010 Feb;55(2):184-9 [[http://www.ncbi.nlm.nih.gov/pubmed/19818531|PMID19818531]] [[https://www.annemergmed.com/article/S0196-0644(09)01281-5/pdf|Fulltext]]

The colour chart instructions and the data for constructing it can be downloaded {{:wikitox:methb_color_change.pdf|here}}  [93 KB]

A computer generated chart for printing can be downloaded {{:wikitox:methb_color_chart.zip|here}}  [121 KB]

{{:wikitox:methhb_chart.png}}