Feeling Blue at St.Emlyn’s

A hypothetical case to illustrate a common problem in the ED.

It’s reassuring to know that as the nights close in and winter approaches (ice on the car today) that there are still people around who want to go out and have a jolly good time. Here in Virchester we have a very lively nightlife with people travelling from all over the world to join in the fun.

A young adult male is brought in from a club having collapsed in a night club. The department is put on standby for a man with low sats and a decreased level of consciousness.

You assemble the team in resus and brief them about the possible causes for a collapse in a nightclub but, when the doors open and the paramedics bring in a man who looks rather odd, Sister whispers into your shoulder ‘Where did they find a Smurf at 2 o’clock in the morning round here?‘. Although you silently admonish her for such a flippant comment you have to admit that he is blue, seriously blue.

The first thing to notice is that this chap is really rather well. He is chatting away and appears to be relatively unconcerned of his predicament. He gets some obs done and they are also counterintuitive to a man the same colour as Papa Smurf sitting in the bed.

  1. Pulse 120 Sinus Rhythmn
  2. BP 125/82
  3. GCS 15
  4. Pupils equal and reactive
  5. Blood glucose 6.2
  6. O2 Sats 78% on oxygen
  7. He is still very blue.
  8. Resp rate 20
  9. A song starts to play in your head…….

So, where now then folks? Got the diagnosis already? Probably, but if not let’s explore a little further.

Top of the list has got to be methaemaglobinaemia. The association of a very blue, previously well man with relatively normal vital signs (apart from the O2 sats) suggests this as a diagnosis. Other causes of cyanosis in a young man would be expected to affect him in other ways, or at the very least lead to a degree of distress and concern in the patient themselves.

There are possible alternative explanations as he might possibly be one of the incredibly rare members of the family with congential methaemaglobinaemia, but he is called Justin and he is not from Kentucky (so it seems unlikely to be honest). It’s much more likely for this to be due to an exogenous source.

He does tell you that he was taking something in the club, but was not sure what it was.

[/learn_more][learn_more caption="What investigation would you like?"] It’s got to be a blood gas. I don’t mind if it’s arterial or venous as it’s the MetHb level that you are after. In our ED we have a blood gas analyser in the resus room so you can get this back in a matter of minutes. If you are going to an ABG for your resus room you should a) have one already and b) make sure it measures MetHb and COHb.

  • FiO2 approx 60% on face mask
  • pH 7.38
  • pCO2 3.2kPa
  • pO2 45 kPa
  • BXS -4
  • Lactate 3.0
  • Hb 14.0
  • MetHb 38%
  • COHb 3%

So the combination of a high pO2 together with a low non invasive O2 sats and a high MetHb confirms the diagnosis of methaemaglobinaemia. [/learn_more][learn_more caption="So what might have precipitated this?"] Well, at this stage you should stop and think about what the causes of MetHb are. Emedicine has quite a comprehensive list here and reproduced below

This is quite a long list but in clinical practice it is likely that there will be clues in the history about the likely precipitant.

In Virchester and particularly if the patient has been brought to us from one of the city nightclubs it is almost always due to the ingestion of nitrates. Typically the ingestion of amyl nitrate which is widely available as poppers, aka: Amyls, Kix, Liquid Gold, Ram, Rock hard, Thrust, TNT etc.

Poppers are widely used in clubs with their use being common in gay clubs, but by no means exclusively so. Although more commonly seen in MSM patients we have seen cases in patients from all sexual preferences. In the UK they are legal to possess but the sale may be restricted. Weirdly I saw them for sale in a petrol station recently which seemed very odd indeed.

Normally amyl nitrate is inhaled through the nose as it evaporates from an open bottle. However, its packaging is often very similar to GHB (Gamma Hydroxy Butyrate) and GBL which is often sold in the same venues but is taken orally. We presume that users get confused and ingest rather than inhale amyl nitrate by accident. [/learn_more][learn_more caption="OK, we have a diagnosis - what are you going to do?"] Here in the UK we usually refer to TOXBASE for poisons advice and according to their website the symptoms and signs in this case are consistent with the MetHb level measured. We would always suggest checking your local guidelines before embarking on any therapy (apart from anything else the guidance may change between this blog post and your next patient).

0-10% Features unlikely
10-30% Mild effects such as blue-grey ‘apparent’ central cyanosis (blue to grey lips, tongue and mucus membranes, and slate grey skin), fatigue, dizziness, headaches
30-50% Moderate effects – weakness, tachypnoea, tachycardia
50-70% Severe effects – stupor, coma, convulsions, respiratory depression, cardiac arrhythmias, acidosis
More than 70% Potentially fatal

For patients with MetHb levels below 20% little, if any, treatment is required and for those with levels 20-30% simple oxygen therapy may be all that is required. However, for patients with levels over 30% and if significantly symptomatic the recommended treatment is with Methylene Blue.

I particularly like Methylene Blue (methylthioninium chloride) as it just amuses me to give a blue dye to a blue patient in order to make them pink again. Childish I know, but I just find it really satisfying. The typical dose advised in the literature is 1-2mg/Kg in a 1% (10mg/ml) solution, with a repeated dose at 20-30 mins if needed. MetHb levels should be rechecked after an hour. [/learn_more][learn_more caption="How does it work?"] The methylthioninium chloride acts by reducing the Ferric Iron of MetHb back to Ferrous Iron of the normal haemaglobin. At the low levels advocated by the poisons centres it reduces iron to treat MetHb, but at high levels it oxidises normal haemaglobin into MetHb!!! It’s a very interesting drug indeed.

Interestingly there are several circumstances when methylthioninium chloride will not work and if that’s the case I would suggest that it is time to phone the poisons centre and to get some more detailed advice. Let’s face it, if you’ve already treated something pretty unusual and it has not worked then it’s a subset of weird. Phone a friend, there’s no shame in that.

Perhaps the most likely reason for failure is glucose-6-phosphate dehydrogenase deficiency as the methylthioninium chloride requires NAPDH to work (which is low in G6PD deficiency).

You might also want to visit the excellent poisons review site for more links and information around Methaemaglobinaemia.

  • 1. Suspect Methaemaglobinaemia in any patient who is unexpectedly blue with few other signs.
  • 2. Recreational drug use is a common cause in many areas.
  • 3. Amyl nitrate is commonly used amongst men who have sex with men (but not exclusively so).
  • 4. Treatment is based on the MetHb level but is most commonly indicated for levels over 30%.
  • 5. The treatment is to give Methylene Blue but it does not always work. If you are failing to drop the MetHb level contact the poisons centre for more advice.
  • 6. Eifell65 are *****

 

Case studies on St.Emlyn’s

  • We do present hypothetical cases on St.Emlyn’s. These are based on the experience of our team as educationally active emergency physicians. For centuries doctors and nurses have used stories to teach and learn from each other. However, we are careful not to break any patient confidentiality rules.
  • As a result if we present a case then it will always be fictional and not relating to any specific case or patient. For example if we present an (anonymised) X-ray or ECG we will create a clinical history that is compatible with the radiological/ECG findings but which does not relate to a specific time, location, patient or circumstance. Whilst it may be argued that this detracts from the clinical learning we believe that patient confidentiality is more important in these matters.
  • We will create time, date, age, sex, details of the patient and their circumstances etc. Our cases are therefore an amalgam of different cases and experiences. Any resemblance to patients treated by us now, in the past or the future is entirely unintentional and accidental. Our cases are presented to help us all reflect and learn, in that way we might become better clinicians for our patient.
  • Vive la FOAM! (Free Online Medical Education).

 

Comments

  1. Janos Baombe says

    If we are talking about enhancers that are common in nightclubs and cause methaemoglobinaemia, it’s worth mentioning the cathinones (extract of khat plant). The most common one is mephedrone also called miaow miaow but a new one commonly called bath salt (which would anyone eat bath salts for pleasure?) can indeed cause smurf like symptoms.

    • Janos P Baombe says

      It cannot be called a drug as it is legal in the UK. You have to use a term
      “Enhancer” is the term what I find to be closest to their effects and legal status…

    • Janos P Baombe says

      enhancer obviously referring to poppers as mephedrone sand its derivates are now illegal in the UK after a period of legal obscurity!

    • Gareth Roberts says

      Nice run through Simon. There are a number of chemicals available of various guises from “reputable” websites and headshops that are obviously not for human consumption. The ultimate aim of these often is to mimic the traditional drugs of MDMA/ pills/ cocaine are you get similar side effect profiles. Often the drugs people believe they are taking are not the ones they are as none of this is regulated. I think its also worth while thinking about the situation around the overdose. Having had recent experience, sadly, not everyone who attends or dies with “recreational” chemical intoxication do so from over jealous partying. think about the quantities involved and ask yourselves whether it is plausible that this happened accidentally.

  2. Andrew Volans says

    I treated a case with methylene blue and like you I liked the almost “homeopathic” aspect of giving a blue drug to a blue person to make them pink. Did you also notice that their blood is brown? I have a photo of a drop of brown blood on a swab next to the blue hand of a patient with a dapsone OD. Every junior in the hospital turned up to see me giving a large bolus of methylene blue since no one remembered having seen it before and I had never done it before either. It worked

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  1. [...] "You assemble the team in resus and brief them about the possible causes for a collapse in a nightclub but, when the doors open and the paramedics bring in a man who looks rather odd, Sister whispers into your shoulder ‘Where did they find a Smurf at 2 o’clock in the morning round here?‘"   Test your knowledge of methaemaglobinaemia via this engaging case study from St Emlyn's. (Okay, sorry – I gave away the first answer… but you're on your own with the rest).  [...]

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