Self Experimentation in Medical Education – LA for ABGs

photoYou are probably aware that many great scientific discoveries have been made when doctors decide to experiment on themselves.

Self experimentation is sort of a tradition – take the famous discovery of Helicobacter pylori‘s role in gastritis and peptic ulcer disease by Nobel prize-winning Barry Marshall (he and Robin Warren were awarded the Nobel Prize for Physiology in 2005). In order to prove H. pylori‘s pathogenic properties, Dr Marshall drank a “brew” made from a suspension of two culture plates of the organism. In this interview from the Canadian Journal of Gastroenterology he states he had:

…read the history of John Hunter’s self-infection with gonorrhea and syphilis

It sounds utterly crazy to any rational person. But I think most doctors are probably a bit crazy and this is almost certainly true of those of us who work in the semi-organised chaos of the Emergency Department.

So, as part of my NHS Change Day pledge to offer all conscious patients local anaesthetic for arterial blood gas sampling (and to perform venous or capillary gases instead whenever possible), it occurred to me that the best way to convince other practitioners that ABGs  were unpleasant enough to warrant local anaesthetic was to have one performed myself.

Without local anaesthetic.

By a (very brave) medical student, to guarantee an authentically painful experience.

On video.

After a night shift.

I’m still bruised.

Et voilà – it might not be Nobel prize or Oscar-worthy, but it convinced me; I hope it will convince you too. Needles and blood-letting from 6:50 onwards.

Read more about why you should pledge for NHS Change Day here and Alan Grayson’s fantastic ABG vs VBG post here.

Huge thanks to Nick Smith, Alan Grayson and our fantastic medical students Mary Aspinall & Chris Wheeler.

Cite this article as: Natalie May, "Self Experimentation in Medical Education – LA for ABGs," in St.Emlyn's, March 1, 2014,

13 thoughts on “Self Experimentation in Medical Education – LA for ABGs”

  1. Just stop doing them, we did years ago, and apart from the usual and expected ill informed dribble about baseline gases (ABG) and oxygenation from the Resp physicians it went well. We still have the odd new resp physician to our hospital put up a fight but it usually dies out. I was surprised as you might be that you could train physicans so quickly.
    The most amusing thing of all was a new department gas machine which although we selected VBG at the machine it electronically went into record as ABG, most of our referral partners did not notice.
    Best advice we offer our JMOs is still, stand away from the machine, look at your patient, most of the information you need is there.

  2. Very brave! and we should all relect on painful things done to patients, but amidst the enthusiasm I felt there was a little bit of bias possible ,what about the difficulty of getting sample I did notice the ‘I dont even mind if you dont get the sample’ comment in1st lignocaine abg, also notice fine needle for lignocaine which could be used for abg

    1. Thanks for your thoughts.

      To be completely fair the comment was directed at the medical students who were under quite a lot of pressure to perform – a lot of footage was edited out (original video was around 20mins in total) so I’m not sure you get a real feel for how long they tried and how apologetic they were! I have been using local anaesthetic for some time and I have noticed no difference in the difficulty of obtaining the samples; I rarely struggle at all to get an arterial sample when indicated. Conversely, if you are someone who struggles it’s even more important your patient is comfortable so local anaesthetic can help increase confidence.

      And while your idea about using the insulin syringe to obtain the sample itself there are a couple of problems; the needle is very short and despite the superficiality of the radial aftery may not actually be long enough to get into the vessel, and secondly the insulin syringe is not pre-heparinised as ABG syringes are. Clots are bad for your analyser and the machines are calibrated to correct for the heparin in the sample (particularly ionised calcium) so I would advise always using a pre-heparinised syringe with the heparin expelled before use, rather than an insulin syringe to collect the sample.

  3. Are VBGs validated for any of the pancreatitis scoring systems? Will a sats probe detect a small amount of shunt (eg sats of 96-97% in a hyperventilating young patient)?

    I still take ABGs, but I have always used lignocaine delivered with a 29g insulin needle.

  4. Gareth Roberts

    great video Natalie and very brave. I agree with all your sentiments particularly questioning your own practice and the need for an ABG. All I would add is that I think its important to discuss the pros and cons with other specialties who may deem an arterial analysis necessary.

  5. Have to agree, very brave of the pair of you. There’s very few of the medical students I meet I’d let near me with any type of needle……

    As a medical student I was always taught that you should use LA as hyperventilation caused by pain / anxiety was likely to result in inaccurate baseline gases (in the same way I suppose as waking up a sedated patient to do pulse oximetry may well lead to an artificially high SpO2). Never questioned it but seemed reasonable on the basis that it did seem a painful procedure.

    In contrast, teaching in my current centre is that single ABG’s are done without LA on the basis that one needle must be preferable to two, but whilst most of us have had venepuncture or a cannula inserted at some point over the years very few of us have had an arterial puncture, and any suggestion that we might perform an arterial puncture on one of our colleagues who favours no LA is looked upon in horror with a certain amount of fear and trepidation ……because it is perceived as a painful procedure.

    Now as an anaesthetist working in Intensive Care I do lots of ABG’s but most of these are done via an A-line. I only do occasional arterial stabs and whilst thinking that I would ideally use LA I suspect some are done without, particularly in obtunded patients. But what of my colleagues? Tried a quick straw poll via departmental facebook page but suspect that was more of a test of my colleagues ability to use social media as only small sample bothered to reply – even so the ratio of LA to no LA was 1:2. Did raise a few interesting points around using LA only in patients who had experienced previous failed stabs.

    As for NHS change day? Well I’m going to follow your examples and warm my LA before putting it into an insulin syringe. That 29G needle has got to be much kinder than the 25G one I’ve always used

  6. This is wonderful! Personally I have never seen an ABG taken with LA and after reading BTS guidelines was wondering how that could be.Then I stumbled onto this blog entry. Great way to challenge our everyday practice.

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  9. I had never heard of using LA for ABGs until I spent 4 months on exchange in a French hospital – it’s standard practice there! Now, as I look down the approaching barrel of FY1 I’m wondering how I can translate that practice here; will I as a baby doctor be allowed to deviate from the norm?

      1. Thanks for your comment, Emily.
        I agree with Simon HOWEVER if you’re starting out as an F1 this is a great opportunity to get involved in some audit, research and quality improvement (and to make things better for your patients). If using local anaesthetic isn’t standard practice in your trust it might be a good idea to find a friendly supportive consultant and do some preliminary research into how often (if at all) it’s used in a specific area (ED or MAU/AMU/respiratory ward might be a sensible place to start) – and then to run an awareness campaign for NHS Change Day and re-audit afterwards for evidence of changing practice. Most trusts are supportive of patient centred interventions like this one and will publicise your pledge. The NHS Change Day hubbies for your area will be able to support you too. You don’t have to sacrifice your wrists like I did 🙂
        Let me know if I can help and good luck!

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