Preoxygenation Pearls

This post might become a regular under the banner “What I learned from Scott Weingart this week!”  Scott runs the EMCrit blog and if you haven’t seen it – do yourself a favour and download his podcasts from Itunes – he is a great teacher, and pitches his education in a practical / pragmatic fashion that is well suited to rural GP Anaesthetic / ED types.

I got in contact with Scott a few weeks back to give my 5 cents on “pre-oxygenation”, basically I (and a lot of Anaesthetists) was taught to think of it as “denitrogenation” of the lungs – aiming to get the ET O2 up to 80 – 90% prior to RSI.  This is true, however as Scott has pointed out in his video response – this is missing a few crucial steps.  You cannot directly translate what we do in OT back to the crashing ED patient.

Check out Scott’s video and demonstration of pre-oxygenation on himself.
Then check out Scott’s “DSI: delayed sequence intubation” concept – this is basically how to preoxygenate a sick patient, and hopefully avoid them crashing on induction. The link then links to another video demonstrating the technique.

This is me learning a better way, it does break a few of the “Anaesthetic Commandments”.
Would love to hear your comments


  1. Casey,

    Great blog and also great to have a rural/remote point of view. I am a ACRRM with almost exclusive expereince in rural and remote australia. Particular the Isa and mining communities in central Qld. I think the problem with all of these RSI rules so to speak is that they come from the anesthetic world. Commonly fasted patients, pre-screened, sats normalised, predicted difficult airways etc.

    Where is the ED airway rule all of the above is not present. I do believe that we need to rethink the RSI paradigm be it DSI or even rsa a RFDS doc I know does the following:

    Standard RSI placement of proseal single use drop a ng tube suck the gastric content up this ensures that the patient is adequately pre-oxygenated then proceeding to traditional intubation. This is conceptually great as we have ensured the patient is pre-oxygenated not on the code brown end of the disassociation curve and that we have ensured that we can oxygenate if we cant get a ETT in! Would love your comments on this

  2. Casey Parker says

    Hi Ray. Interesting technique. I have to say, I am not too comfortable with an LMA in a resus / trauma case up front. I completely accept that it is great if you are not prepared to tube or the right skills are not present, however in my practice it is unusual not to be able to get the ETT down either clean or with a bougie. (Probably < 5% of cases) If you can get the tube down quick, then I reckon this is the best option. THe LMA / proseal is a good plan B and has saved my bacon a few times, and has a place as plan A when the patient arrives on your bed before you have had a chance to do any prep / get the team together - this still happens to me a bit! I teach this to my JMOs / nurses who might get stuck at 3 am, waiting for one of the senior MOs to arrive. I have yet to have a chance to use the DSI that Scott and Emcrit descibes - but I think that this is a good option in the sick / trauma patient where you have a few minutes to get it together and recruit all the lung you can before dumping in your drugs. Thanks for reading, keep the comments coming! Casey

    • Casey,

      I agree with you completely. I always go for the ETT first line. I think the proseal/lma is best in the situation where you starting at sats of 80% or lower or if you have the equipment i think DSI is the way to go. I actually got to try the DSI technique on Christmas day last year:

      40 yo previously well with history of mild asthma. Get a call from Ambo patient has severe asthma 5mins later get a repeat call patient suffered respiratory arrest in the end resp drive driven entirely from small doses of IV adrenalin. Sats 80% on BVM, ETCO2 80 RR 6. I then Gave her 1mg/kg of ketamine placed her on bipap then ensured adequeate IV access. Also had the ambos applying chest wall compression to help with expiration then with her sitting once she was on 100% sats for a couple of minutes did an awake intubation and pushed the paralytic. This was a great example of Scott’s DSI technique.

      • Minh Le Cong says

        Ray, that is an awesome case and great example of how you can learn meaningful things on these medical
        blogsites that can make a real difference in the difficult cases!

        I slightly modify the DSI technique and tend to drop in a Fastrach ILMA as the first action and ventilate as soon as I can to get the hypoxia corrected. Then when things are more stable and I am ventilating fine, I can decide to just keep with the ILMA or try for a blind ETI attempt via the ILMA.

        A few times I have just dropped in the LMA supreme and stuck with that if I am getting good ETCO2.

        Awake intubation on a periarrest severe asthmatic ! Wow! Who dares wins!

        • Minh,

          Tell me about who dares does win. But what i had was at that stage a spontaneous breathing patient, now sats of 100% i thought i will try and have a look at the cords ( i have heard from the South African Isa crew that they have tubed just with ketamine no paralytic and also from the the blogs out there) if i see the cords place the ETT then push the paralytic. If not i still have a spontaneously breathing patient with patent airway. She actually handled the laryngoscope quite well got a bit of cough with the ETT in place but that settled very quickly once the paralytic was pushed. I then use more advanced techniques or as you do place the LMA.

          This has reinforces some things that I have started to question about the whole RSI and airway dogma that comes from anaesthetic’s the emergency airway can be a completely different beast and we need to adapt to out surroundings and situations. What are your thoughts on this?

          • Minh Le Cong says

            I agree with you about questioning the RSI/airway dogma as I have come to the same conclusion that emergecny airway management is a different beast to what we were taught in hospital anaesthesia.

            What you did with your severe asthmatic patient is similar to what Louis Peachey did in Atherton with a guy whol had a self inflicted shotgun wound to the chin. He pushed 0.5mg iv fentanyl and did an intubation using a bougie without any other drugs apart from some topical anaesthesia.

            Cliff Reid described an awake intubation he assisted in with remifentanil for a patient with angioedema I think.

            SO you are right Ray…its good sometimes to consider these alternative approaches to securing the airway. YOu just got to be prepared to rescue the situation if it does not go your way.

            I have to say I have seen a number of cases where people did try to tube with ketamine sedation alone and it just did not work..laryngospasm..vomiting etc.

            Levitan told me once a great tip “The closer a patient is to dying , the less worried I am about pushing the durgs and getting on with securing the airway.” His point of course is that if a patient needs an emergent airway for resuscitation then you want your best first pass chance of success and that usually entails a full RSI approach with a paralytic.
            Sometimes as you know you just need the paralytic to get the tube in and you do not need any sedation as their BP is crap.
            Do you still use cricoid pressure on all your emergent intubations?

          • Ray Gadd says


            I don’t use cricoid at all. The only time i have someones hand on the neck is when i am doing ELM. I find that it often worsens my view. I have been to Levitan’s airway course in Baltimore and found his approach fantastic. it was amazing to see on the multiple cadaver models the variable way that cricoid would obscure your view of the cords.

            Louis discussed that case with me it was an interesting case to say the least, would have been some tense moments but louis is so calm to start with he probably didnt break a sweat.


  3. Minh Le Cong says

    so you tube all cardiac arrest patients still? Despite the evidence and published guidelines?
    I must say I use a lot of LMA work in resus, partic in arrests and can’t understand why docs find it hard to shift the perception that the plastic cuffed tube is better.

    You are aware there are studies demonstrating worse mortality in out of hospital arrests for intubated patients as opposed to not?

    dont get me wrong intuitively it s a biologically plausible arguement to say an ETT is better than a LMA. Its difficult though to prove it.

    If the LMA is sitting right and you got good ETCO2 I am not sure what you are adding by ETI. The second generation SGAs can drain the stomach and protect against aspiration, maybe not as much as an ETT but even an ETT is no guarantee as you all know from ICU studies.

    And in kids, if you are still sticking down uncuffed ETT, well how is that better than a LMA for aspiration protection? We should all be using the modern cuffed paeds tubes really!

  4. Minh Le Cong says

    cool you have been to the Baltimore course..I am jealous!

    About cricoid pressure..there was a lecture about this at this year’s ANZCA Airway conference. Basically most Australian anaesthetists are aware there is little evidence to support its use yet cannot bring themselves to do a proper controlled study of it nor give it up completely!

    At best they recommend using cricoid pressure and releasing it if you have a poor view.

    They cite medicolegal reasons for continuing to use it. My take on it after reviewing the evidence and talking to colleagues like Levitan, anaesthetists etc is to use cricoid pressure in high risk cases of aspiration such as SBO or intoxication or pregnancy etc.

    I think we should be providing better training for cricoid pressure and researching it properly. at the end of the day, if its going to be a difficult airway, or turning out to be an unexpectedly difficult airway, I agree its best to abandon the cricoid pressure and get the tube in as quick as you can. One relevant case to review is Mr Ewing’s case where cricoid pressure was maintained during the whole intubation which failed..anyway you can read what happened here

    Dogma is hard to shift

    • My goodness what a mess. The course was great I went o NY for holidays and thought a quick trip there would be great. The course is amazing. Very confronting 16 cadavers in a small room very confronting. But as you are aware his tips and experiences was worth it. It was also good as we had 16 cadaver to see the wide range of anatomy thats out there.

      Dogma is hard to shift.

Speak Your Mind