Methylene blue as a treatment for methaemoglobinaemia.
Date First Published:
July 13, 2010
Last Updated:
July 14, 2010
Report by:
Daniel Ferris, Medical Student (University of Manchester)
Search checked by:
Daniel Ferris, University of Manchester
Three-Part Question:
In [adults with methaemoglobinaemia due to local anaesthetic use] is [methylene blue better than placebo] at [reducing morbidity and mortality]?
Clinical Scenario:
A patient has received a benzocaine spray for pain relief during insertion of a nasogastric tube, soon after he becomes remarkably cyanosed. methaemoglobinaemia is diagnosed. What would be the best treatment option for him?
Search Strategy:
Using Ovid interface; Medline 1950 to June week 4 2010, Embase 1980 to 2010 week 26, Cochrane database of systematic reviews 2005 May 2010
Search Details:
[exp methemoglobin$/ OR methaemoglobin$.mp.] AND [methylene blue.mp. OR exp Methylene Blue/OR Methylthioninium chloride.mp.] AND [exp Anesthesia, Local/ OR (local adj1 anaesthe$).mp OR exp Anesthetics, Local/ OR exp bupivacaine/ OR bupivacaine$.mp. OR lidocaine/ OR lidocaine$.mp. OR exp prilocaine/ OR prilocaine$.mp. OR exp lignocaine/ OR lignocaine$.mp. OR marcaine$.mp.] LIMIT to English language and humans.
Outcome:
295 papers found 7 of which were relevant.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| Methemoglobinemia related to local anesthetics: A summary of 242 episodes. Guay J 2009 Canada | 242 patients (160 adults) with methaemoglobinaemia due to local anaesthetics. | Meta-analysis | Patients recovering after Methylene Blue administered | Authors advice methylene blue should be first line treatment in those without glucose-6-phosphate deficiency. | Search methods limited. Only one database used and references checked. Explicit methods for inclusion not stated. Only why some studies were not included. Methodological quality not assessed |
| Intraoperative detection of methemoglobinemia in a patient given benzocaine spray to relieve discomfort from a nasogastric tube: A case report. Young B 2008 USA | 27 year old male with methaemoglobinaemia due to use of benzocaine oral spray. | Case report | Patient recovering after Methylene Blue administered. | Patient fully recovered after methylene blue administered. | No report of long term follow up. |
| Methemoglobinemia induced by exposure to topical benzocaine for an awake nasal intubation - A case report. Lin S et al 2007 China | 48 year old female with methaemoglobinaemia after benzocaine spray use. Received 70 mg of 1% methylene blue over five minutes. | Case report | Patient recovering after Methylene Blue administered. | Patient fully recovered after methylene blue administered. | No long term follow up offered. |
| Prilocaine induced methaemoglobinaemia in a medically compromised patient. Was this an inevitable consequence of the dose administered?. Adams V et al 2007 England | 45 year old female receiving prilocaine for dental procedure, causing methaemoglobinaemia. 43 mg methylene blue unspecified concentration administered. | Case report | Patients recovering after Methylene Blue administered | Patient fully recovered after methylene blue administered. | No long term follow up. Concentration of methylene blue not discussed. |
| Methemoglobinemia and transesophageal echo. Jiminez M et al 2007 USA | 56 year old female recieved benzocaine spray which caused methaemoglobinaemia. Administered methylene blue 60 mg over 5 minutes, unknown concentration. | Case report | Patients recovering after Methylene Blue administered | Patient fully recovered after methylene blue administered. | Patient not adequately described. No long term follow up. Preceding events not adequately described. |
Author Commentary:
The search revealed good evidence for the use of methylene blue to treat methaemoglobinaemia caused by local anaesthetics. Although the evidence was retrieved from case studies, there were over 200 positive reports on its successful use. It must be noted that in patients suffering from glucose-6-phosphate deficiency methylene blue will not work and may cause haemolytic anaemia.
Bottom Line:
Methylene blue should be used as the first line treatment for those suffering from methaemoglobinaemia due to local anaesthetic toxicity.
References:
- Guay J. Methemoglobinemia related to local anesthetics: A summary of 242 episodes.
- Young B. Intraoperative detection of methemoglobinemia in a patient given benzocaine spray to relieve discomfort from a nasogastric tube: A case report.
- Lin S et al. Methemoglobinemia induced by exposure to topical benzocaine for an awake nasal intubation - A case report.
- Adams V et al. Prilocaine induced methaemoglobinaemia in a medically compromised patient. Was this an inevitable consequence of the dose administered?.
- Jiminez M et al. Methemoglobinemia and transesophageal echo.