Shock Trauma Center (STC) Failed Airway Algorithm

The American Society of Anesthesia just released their new difficult airway guidelines. Of course, I’ll be reviewing them on the Practical Evidence Podcast.

Those guidelines are a bit too involved for Emergency Medicine and Intensive Care. For us, I recommend the Shock Trauma Algorithm. I modified it somewhat to fit my own prejudices (as usual).


Click on the image for full-size

The approach was validated in this study:

[Stephens CT, Kahntroff S, Dutton RP. The success of emergency endotracheal intubation in trauma patients: a 10-year experience at a major adult trauma referral center. Anesth Analg. 2009 Sep;109(3):866-72.]

Couldn’t be easier to remember and use.

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      • Jakob Mathiszig-Lee says

        Completely agreed. I think it’s ludicrous when emergency algorithms take more then half a second to read.

      • Jason C says

        Am I reading this wrong or does the ASA guideline actually read “Can’t Bag mask –> Can’t make an LMA work –> Can’t ventilate, Can’t intubate –> Call for help and go back to BVM/LMA which from earlier attempts did not work only to somehow possibly end up successfully ventilating the patient?? To me that just sounds fundamentally wrong unless my neurons aren’t synapsing again…..

  1. Minh Le Cong says

    Algorithims are really only good for planning, not so good for doing.
    THE STC one is simple enough to be actually used during a procedure..not that I recommend that but its simple enough to memorise and apply.

    You could have the resus room lifeguard reading the STC algo and acting as a safety guide

    I partic like the emphasis in the STC algo on using ETCO2 waveform monitoring to assess efficacy of BVM or SGA ventilation. Serves dual purpose..good way to heck ventilatory performance but also useful check of working capnography, before intubation!

  2. says

    This algorithm is reassuringly virtually identical to the one I developed back in my heady junior registrar days at my old shop in Perth, WA in the early noughties. The thing I’d add is to CHANGE SOMETHING between laryngoscopy attempts – position, bougie, operator, ELM…any or all…but something. No point in just hammering away doing the same thing! I also had a prominent “call for help” red arrow off to the side right at the start

  3. Andreas Krüger says

    Nice post. We are teaching the same difficult airway management algorithm to all traniees (and consultants). The algorithm is far less in use after we routinely paralyse at the same time as we push the sedative.

    I would like to stress the concept ” if you have an airway- don’t spoil it”.
    In my experience ( anaesthesia) a sub-optimal BVM airway/ LMA is far more common than a real cannot ventilate-cannot intubate situation. In these cases there is seldom an appropriate etco2 wave.
    Don’t spoil a sub-optimal (but working) airway by multiple attempts- call for the best intubator available and hold further attempts.

    • says

      Andreas, I see where you are coming from. This algo is intended for the intubation of the critically ill patient. The best intubator available should be doing the airway from the get go. While the ETCO2 waveform may not be appropriate as if it was an ETT, there should be a ET demonstration of gas exchange or else you are probably not exchanging gas.

    • says

      Andreas, I agree with you completely. The reality is that whilst everyone involved in airway management should have achieved an appropriate level of airway expertise, there is a variation in the degree expertise beyond this. I would agree with Scott that if you forsee a difficulty and you know someone has particularly advanced airway skills you should get them in from the start. The difficulty is that many difficult intubations aren’t anticipated as such and it may not be realistic to have the most skilled intubator in the hospital standing at the head of the bed for every intubation. If you can ventilate via a FM or LMA then do so and buy some time to get all your resources in place before instrumenting the airway again (if that is the plan at all). Low saturations are better than no saturations!

  4. Minh Le Cong says

    I agree with Scott. ETCO2 waveform demonstrates gas exchange and more importantly a sufficiently patent airway to allow such. It is a difficult transition but we need to accept the reliability of the ETCO2 in monitoring airway patency and adequacy. It is not good enough to just look for chest wall rise anymore. Many times you can be ventilating fine with good gas exchange and ETCO2 and in these big chested patients you see almost no chest wall movement!
    The situation is different of course if you are insufflating oxygen where your primary goal is not gas exchange but oxygen delivery to alveoli..ETCO2 will not help you here.
    but that is not what we are talking about with the STC algo
    On the issue of the best intubator…I guess coming from Prehospital care..we are it..there is no other intubator !
    I do worry about such strategy whereby relying upon a better intubator to arrive is built in to the decision making.
    I am not so sure it is actually a very helpful concept.
    I think having a team approach is in fact more helpful. Not that there is a better intubator in the team(which is the current paradigm) …but that the team helps each other to be flexible and responsive to a rapidly devolving situation. The team drills rehearsed tactics like a well trained squad, the goal is clear and all techniques are given equal priority as long as the goal is steadily advanced upon.

    The challenge of course is what if you in fact have no team to begin with. what if they are all strangers called in to handle the one emergency?

    I think this is the value of such an algo simple as the STC one.
    You could display that on a big wall monitor and point to it and say this is our game plan..lets go with it. Assign a life guard to be the governor if the algo and guide the team. No better intubator..just a better team dynamic.

  5. Andreas Krüger says

    Well I agree with you both. My comments were based on the reference from Shock Trauma above. As far as I can see the context in that paper is in-hospital. I totally agree with Minh that prehospital ET is a different issue. No help is usually available, so no need to put “shout for help” in the algorithm. As Minh point out, a drilled team might be the substitute.
    I would still argue that in a “cannot ventilate, cannot intubate” situation, my biggest concern would be hypoxia, and not hypercarbia. As such, if I can manage to oxygenate the patient, at the cost of retention of Co2, I would be happy. I mean, in my opinion it would be wrong to remove a half working LMA ( if that was the only thing I managed to oxygenate the patient with) to proceed to cric if any other option is available e.g a consultant on call. I’m working in Norway, and usually it is the anesthestetists that do all adv airway management (OR, ED, ICU and prehospital). No emergency physician speciality here yet. So my comments not only based on the OR setting.
    The STC algorithm is actually almost identical to what we apply in all difficult airway settings at our hospital. The way to success is to keep the team tranied, recognize trouble before induction (if time), and always change something between attemts. And always remember; if in trouble: do not spoil a half working airway.

    • says

      Andreas, I believe we are not on the same page on the purpose of ETCO2. It has nothing to do with hypercarbia. It is a guarantee of gas exchange. It is an oxygenation issue, not a carbon dioxide issue.

      • Andreas says

        Emcrit, I’m sorry. I guess the my effort to discuss the topic using a foreign language went slightly the wrong direction….
        What I probably ment to say was: no doubt an et co2 wave gives a reliable indication of gas exchange. My point was: ( trying to formulate correctly this time) getting an etco2 wave during airway management can sometime be difficult, especially during BVM ventilation (which is the most serious problem in a cannot ventilate cannot intubate situation). If absent etco2 wave is the only measure of cannot ventilate, especially junior docs will have to enter the difficult airway algorithm too early, probably creating more problems than needed. Depending on the onset of the muscle relaxant in use it might be a varying time before an etco2 wave appears and indicate adequate gas exchange.

        • says

          This has not been my experience. If a BVM breath goes in, when the patient expires there will be ETCO2 waveform. There is no where else for the breath to go even if there is a slight leak around the mask. This is what the BVM PEEP valve is predicated on as well. If you are not seeing a wave, you are not oxygenating or ventilating.

  6. Minh Le Cong says

    I have a paper under peer review now where we demonstrated the feasibility of ETCO2 waeform capnography using a face mask and main stream sensor. I have been doing this to monitor my ketamine retrieval sedation for 5 years now. It indicates adequate airway patency and gas exchange in a noisy environment where you typically cannot observe chest wall movement during certain phases of transport.
    I fail to see why it would not be an even better monitor of adequate BVM face mask ventilation. This is a simple brilliant idea. The true power of FOAMEd that continues to deliver for my own learning and airway skills development.
    A few months ago I assisted a colleague to perform an emergency RSI in a remote location. He had not done one for a while. The tubing went fine but he was anxious to confirm placement with ETCO2 . Our sensor and monitor was having some issues, perhaps still warming up so for a while there we had no ETCO2 confirmation. There was no chest wall rise at all in this big chested patient, but I could hear good AE bilaterally and SaO2 did not deteriorate. after a minute or two, capnopgraphy began to work and show a normal waveform.
    Would it not have been better to have prepared the ETCO2 and test it during BVM ventilation prior to intubation, perhaps after RSI drugs have gone in and waiting to intubate, a couple of gentle BVM ventilations to establish working of ETCO2 as well as ease of BVM?
    As for having an inadequate ETCO2 during BVM leading to doing a cric too early, I would rather a colleague err on the side of caution than wait for the pulse ox to drop. If there is no ETCO2 trace at all, all things being equal, to my mind that equates to complete airway loss with BVM and the need to proceed with your failed airway drill.

    • says

      As to ETCO2 for BVM adequacy, love to say it was mine, but the first day I walked into fellowship, the anesthesiologists were doing it in the trauma bay and I smacked myself in the head. Makes a ton of sense.

      We always blow to know before using ETCO2 in a real pt, so we are sure the equipment is not the issue.

  7. says

    I agree with having ETCO2 in place during preoxygenation and it highlights why there needs to be more common training programs across multiple critical care disciplines to allow this exchange of ideas (as this is routine practice in anaesthesiology but not yet in other crit care settings). It does a few things:

    1. It makes you check that the ETCO2 monitor is working

    2. It gives you an indication of the adequacy of the seal with the face mask prior to giving any induction drugs (i.e. if you can’t get a good enough seal to get an ETCO2 trace during pre-oxygenation you are unlikely to have a good enough seal to positive pressure ventilate with a FM if this is necessary later as a rescue technique if intubation is unsuccessful.

    3. It means that ETCO2 is connected and ready to go to assess the adequacy of face mask ventilation if this needs to be implemented.

    Equally I’ve found there are things anesthesiologists can learn from the other crit care disciplines. The most striking is the allocation of roles during intubation. In Australia where cricoid pressure is used routinely in fasted patients, this role is usually assigned to a dedicated individual in ICU & ED, with the airway assistant being a distinct role dedicated to equipment. In the operating theatre (even with critically unwell patients having emergency surgery) it is commonplace for the airway assistant to perform cricoid as well as preparing equipment. This means that cricoid pressure may be compromised due to the distraction of preparing other equipment. It also means that often the only other person in the room with significant airway experience is marooned with one hand committed to applying cricoid pressure.

    Whether you believe in cricoid pressure is a separate argument – but if you’re going to do it then at least do it properly and don’t let it compromise other aspects of airway management.

  8. Andreas Krüger says

    Some good points here. I would like to add that having an etco2 wave during preox probably indicates an optimal EtO2 ( if no EtO2 is available). During OR inductions ( especially in pts with low FRC; pregnant, ileus, neonates) I always aim for an EtCo2 wave which is a prereq for max EtO2. It is a free and very important safety manouvre before risky inductions. Some may feel that keeping the mask thight enough to get an appropriate EtCo2 wave means discomfort for the patient, but in my eyes it is simply a question of communication and adjusting the PEEP in the circle ( as with NIV initiation).
    But all things have exceptions… If EtCo2 wave is absent after a direct ET visually placed in the trachea (e.g. in the case of severe bronchospasm, or circulatory collapse) What do you guys to then? Pull the tube? I know its kind of far-fetched but it do happen, probably as common as a real cannot ventilate cannot intubate situation. Just curious.

    • says

      At least with the current generation of monitors, it doesn’t happen. If the patient has a pulse, there will be ETCO2. If the patient doesn’t have a pulse, but they are getting CPR you will have a waveform. The ETCO2 value may be quite low, but there will be a waveform with gas exchange. The references for this are elsewhere on the blog for the purpose of assessing intubation during cardiac arrest.

  9. Jim Carroll says

    Anytime I approach a potentially dodgy airway, I take myself down your algorithm right from the get-go. That is, I thread a bougie and act like an “attending” — optimizing everything and verbalizing what i might need — “BURP” maneuver, patient positioning, inline stabilization, etc. Your first shot is still your best shot. If you think you might need a bougie, you probably need a bougie, and it isn’t going to hurt anything.

  10. Lexi says

    I am a critical care nurse at a large urban hospital. Ever since I listened to the podcasts on difficult airways this algorithm always comes to mind when we are intubating a patient. This morning at the end of my shift we had an unfortunate situation where a patients respiratory status was failing to improve on bipap and the decision was made to intubate. The patient was very obese and you could see that her airway was going to be a problem. The nurse anesthetist arrived. Several staff members raised concerns about the patients airway prior to starting and suggested getting the glidescope out. She attempted to intubate the patient over and over unsuccessfully for 20 minutes before asking for surgey to be paged to cric the patient. By the time the surgery team arrived the patient had lost a pulse and we were coding her. Chest compressions had to be held while the surgeon was working. If they had an algorithm in place for difficult airways the patient could have be trached in a more controlled situation and we would have probably avoided coding her all together. We luckily did get the patient back, it’s too early to tell what her neurological outcome will be.
    I was so disappointed in how it all unfolded. When it comes down to it the decision to cut someone’s neck to save their life should not be a difficult one.

  11. Mio says

    I love the simple check list or algorhythm, I know in high stress situations my IQ drops significantly especally when I am emersed in providing care.
    In a prehospital or interfacility transport of critical patients ETCo2 set up and attached from the very beginning also saves hands and space, and I could not agree more with Minh that to hear or see in the dark noisy and vibrating cabin, where most of the ambiant noise is in the same range as the noises you are trying to hear is not a reality. A value and a wave form that you can see is the gold standard of confirmation especally in that enviorment. In my experience there is not alot of space in a Leer Jet or Astar, and only a bit more in the King Air but planning in the unplanned situation saves time, frustration and people.
    Also I agree with Lexi that sometimes video assisted technology simply allows us to come to that difficult choice much more quickly than we might otherwise get there.
    I also feel that while it may only be semantics to some, I do not much care for a surgical airway being called a failed airway plan, I understand the verbage and the prefered method would be to get an airway from the top side. However, properly done it is a fantastic airway and, while perhaps a bit of a poor comparason, it does seems a bit like calling an art line a failed blood pressure plan. We need to do what the patient needs us to do.
    As a flight paramedic I have only preformed two surgical airways and I fear I waited too long on both. I personally can not agree more with the need to be ready to do the most invasive procedures in the most stressful situations.
    My copy of “On Combat” is all but worn out in sections, a reminder of the importance of training to combat the challange of the stress response.


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