|LETTER TO EDITOR
|Year : 2018 | Volume
| Issue : 6 | Page : 475-476
Methaemoglobinaemia: Recognition and realisation at bedside
Subramanian Senthilkumaran1, MP Senthilraj2, Narendra Nath Jena3, Ponniah Thirumalaikolundusubramanian4
1 Department of Emergency and Critical Care, Bewell Hospitals, Erode, Tamil Nadu, India
2 Department of Emergency Medicine, Hamad Medical Corporation, Doha, Qatar
3 Department of Emergency Medicine, Meenakshi Mission Hospital and Research Centre, Madurai, Tamil Nadu, India
4 Department of Internal Medicine, Chennai Medical College Hospital and Research Center, Trichy, Tamil Nadu, India
|Date of Web Publication||11-Jun-2018|
Dr. Subramanian Senthilkumaran
Department of Emergency and Critical Care Medicine, Bewell Hospitals, Erode, Tamil Nadu
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Senthilkumaran S, Senthilraj M P, Jena NN, Thirumalaikolundusubramanian P. Methaemoglobinaemia: Recognition and realisation at bedside. Indian J Anaesth 2018;62:475-6
|How to cite this URL:|
Senthilkumaran S, Senthilraj M P, Jena NN, Thirumalaikolundusubramanian P. Methaemoglobinaemia: Recognition and realisation at bedside. Indian J Anaesth [serial online] 2018 [cited 2021 May 12];62:475-6. Available from: https://www.ijaweb.org/text.asp?2018/62/6/475/234011
Undiagnosed intraoperative methaemoglobinaemia and its clinical aspects were highlighted by Verma et al., In the report, authors had noted the 'saturation gap' which is the key to suspect and diagnose methaemoglobinaemia. We provide three traditional, bedside methods to recognise methaemoglobinaemia which can be practiced even at remote health-care centres without any analytical equipment or electricity.
Blood samples with a methaemoglobin concentration >20% have an evident chocolate-brown colour. To distinguish this, pass 100% oxygen in a tube that contains the dark blood. If the blood continues to remain chocolate-brown/dark, it indicates the presence of methaemoglobin. An alternative is to place one to two drops of blood on a white filter paper and expose it to atmospheric oxygen. If the chocolate-brown colour does not change with time, it makes one to consider methaemoglobin. In contrast, deoxyhaemoglobin appears dark red initially and then brightens after exposure to atmospheric oxygen.
Furthermore, one can do the cooking test  by placing a clotted blood sample in a test tube inside a boiling water bath. On cooking and cooling, the blood sample containing methaemoglobin will turn pink, whereas normal blood will appear dark brown.
Apart from the above three, Shihana et al., had developed a colour chart which not only facilitates diagnosis of methaemoglobinaemia rapidly, but also assists in the estimation of the percentage of methaemoglobin present in the blood sample in a semi-quantitative manner. Interestingly, in 2011, this colour chart was included in the national guidelines for the management of poisoning as well as in the curriculum for clinicians and nurses in Sri Lanka.
Now a specially designed pulse oximeter is available to measure both methaemoglobin and carboxyhaemoglobin (Rainbow-SET Rad-57™ Pulse CO-Oximeter, Masimo Inc., Irvine, CA, USA) using eight wavelengths of light. In addition, this bedside equipment provides continuous readings of methaemoglobin. Indeed, scholars have found out the usefulness of Raman spectroscopy and infrared scanner to detect methaemoglobin which is less expensive and has high accuracy.
All the three traditional qualitative procedures are simple and skill based, useful to recognise methaemoglobin in intraoperatively and even in remote resource limited health centres. Hence, students of health sciences should be taught, demonstrated, and trained to carry out any of these.
From the point of patient safety, doctors and nurses may be oriented on these bedside methods to suspect and manage cases of methaemoglobinaemia with appropriate measures in time without delay. However, research studies are needed to assess the sensitivity, specificity, accuracy, positive predictability and cost-effectiveness of these bedside qualitative and semi-quantitative methods, and compare them with quantitative methods using Raman spectroscopy and infrared scanner.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Verma S, Sathpathy AK, Srinivas U, Reddy S. Undiagnosed intraoperative methaemoglobinaemia. Indian J Anaesth 2018;62:72-4.
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Senthilkumaran S, Balamurugan N, Ananth C, Thirumalaikolundusubramanian P. Methemoglobinemia and bedside diagnostic test: Ready for prime time. J Postgrad Med 2014;60:213-4.
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Shihana F, Dawson AH, Buckley NA. A bedside test for methemoglobinemia, Sri Lanka. Bull World Health Organ 2016;94:622-5.
Bickler MP, Rhodes LJ. Accuracy of detection of carboxyhemoglobin and methemoglobin in human and bovine blood with an inexpensive, pocket-size infrared scanner. PLoS One 2018;13:e0193891.