Now this is a huge post, apologies in advance – goes a bit over the usual 2 minute read I aspire to! But… this is gold.
Ever been in a “Can’t Intubate, Can’t ventilate” scenario - if you said ‘no’ then lucky you. It is a rare occurrence in Airway management but one which has a very high mortality – and sadly often the harm is iatrogenic, ie. our fault.
In my career I have witnessed one true CICV scenario when in training and it scared the pants off of me. If you want the details they are a matter of public record in the Coroner’s Findings into the death of Rachael RASMUSSEN. (FYI the Dr Casey in this report is not me) I was a “fly-on-the-wall” trainee that day and saw some great Anaesthetists struggle with a CICV scenario which was entirely avoidable.
Since then I have been involved in 2 emergency surgical airways and which have gone well, mainly as a result of the training my colleagues and I have undertaken after having our pants scared off. In my opinion, this the ‘Elephant in the Airway’ that nobody is talking about. We all know that surgical airway is down the bottom of the difficult intubation algorithm – but how many of us are confident enough in our training and decision-making to make the best of such a disastrous situation?
Here in WA we have a wonderful training facility based at Royal Perth Hospital which has done a lot of research into the CICV scenario using wet-lab simulations on sheep. Dr Heard and his team have published their CICV Algorithm based on the experience derived from hundreds of trials using anaesthetic trainees (the sheep were the ‘guinea pigs’, not the trainees – excuse my Irish logic).
Anyway after spending a bit of time debating my preferred Surgical airway technique with my colleagues I decided to get the low down straight from the horse’s mouth (way to many animal puns in this post) and do an interview with Dr Andy Heard. Here is the proposed algorithm from Dr Heard’s paper from Anaesthesia, 2009 for your reference.
1) I am a rural GP-anaesthetist and I do a list a week, I also do some minor surgery on a regular basis. I rarely/never use the fibreoptic kit, surgical airway kits or jet ventilator.
To answer this question in full would require two pages, but I will be brief. My algorithm has been developed primarily as a plan for airway specialist trained in anaesthesia. Ultimately the skill mix of other groups may well mean that they would be better attempting a different path. E.g. an ENT surgeon should use a scalpel blade. Which approach is appropriate would be a decision for the individual. Note that NAP4 surgical techniques were often performed by specialised airway surgeons with all the theatre backup they would be used to. No technique is infallible; our algorithm encourages a systematic progression through techniques, with the pathway moving from cannula to a scalpel technique if required. I would recommend that you are prepared for all eventualities i.e. familiar with both cannula and scalpel to allow you a better chance of success. If this is appropriate, then a cannula technique performed along our guidelines does not cause major difficulties with scalpel techniques but a scalpel technique that fails but causes intra-tracheal bleeding unfortunately makes aspiration of air as an end point very difficult and leads to cannula failures which would have been successful. Ultimately there are a lot of requirements for successful management of this scenario: teaching, training, equipment availability etc. which can also affect your choice. I can add that we have regular E.D physicians coming through the wet lab, at least 2 of whom have successfully saved a patients life with a cannula technique and then secured the airway with a Melker.
(2)In your trials the scalpel-bougie technique was 100% successful and recorded a consistently shorter "time to ventilation" than the other approaches. Is this a reasonable first-line technique in a crisis?
This is actually a similar question to number one. An (our) observational study on success is no guarantee of success. These were all on easy necks with easy to palpate anatomy. Performing a scalpel technique with no identifiable anterior neck anatomy is inherently far more difficult and not appropriate for the scalpel bougie. I occasionally have people attend the wet lab and say that the scalpel bougie is their “take home” choice. I point out that if that is their plan, probably in 1/3 of patients they will not be able to proceed due to difficult anatomy. You can proceed with a cannula no matter what the anterior neck airway anatomy. Part of the problem, in anaesthesia at least, is that speciailists struggle to make the decision to go round the front of the neck. Giving a simple choice, with no decision process required of a cannula first every time encouraged people to attempt rescues oxygenation through the front of the neck. This reluctance is well documented in critical events (e.g. Elaine Bromiley). They can still move onto a scalpel technique if required.
(3) Your algorithm places cannula-cric as the 1st line intervention. The recent NAP4 audit was critical of needle-cric techniques noting a high failure rate (60%). Can you comment on this?
Again requires a long answer. But put simply we have pointed out for many years now that most of the anterior neck airway equipment “designed for purpose” is unreliable and often unsuccessful in the emergency situation. Hence we have rewritten the plan, techniques and changed the equipment to suit the requirements of the CICO scenario. NAP4 has often very nicely validated our points in regards to this. Also many (if not all) of the surgical airways using a scalpel were completed by surgeons (in particular head and neck surgeons), not anaesthetists. They also point out that they may have missed many events, including successful cannula that were not reported. There were no recorded details of operator experience or training. Emergency airway management through the anterior neck is not something we do every day. To try and use an analogy – If we were to advise all surgeons to use a laryngeal mask (which they had never used before) and asked them to use them for the first time in anger in the worst airway scenario of their life, the results would not be reassuring; in a NAP4 equivalent study looking at airway disaster for surgeons. If interpreted as NAP4 seems to be interpreted against cannulas, it would convince surgeons to never use a laryngeal mask in an airway emergency. If they also audited anaesthetists who used laryngoscopes then they would say that laryngoscopes worked very well and hence all surgeons should just switch to using laryngoscopes. This would not improve their outcomes, but would end in disastrous results. Even with some training you do not gain satisfactory laryngoscopy skills easily on a manikin. What they would need is training in the technique which suited them, using appropriate equipment. Looking at the surgical “High success rate” that they compare against the cannula low success rate. Only 11 of the scalpel surgical airways were true emergencies in NAP4, and of these 2 patients died. This is with surgeons who know how to hold and manipulate a scalpel blade, have diathermy ready and know how to use it, are in their relative “comfort zone” i.e. using a scalpel not a cannula and in many are airway surgeons who do incise the neck every day of their working life. If this is to become the gold standard for all airway specialists how are we ever going to teach everyone to manage this situation? I suggest the only way would be for all airway specialists to have to undertake at least 1 year of ENT training. We purposely moved away from standard scalpel techniques in our plan for a variety of reasons, one as stated to allow a direct path onto the algorithm to avoid decisions and fixation errors, and secondly because our, now quite extensive, experience of scalpels held in anger by anaesthetists and other specialists in the wet lab showed very poor results. This has been addressed in some way by the scalpel bougie technique which minimises scalpel manipulation and hence scalpel skills, but this technique is only appropriate if the airway anatomy is palpable. Trying to give anaesthetists or other specialists the skills to manipulate a scalpel in anger in a stressful environment is a virtually insurmountable task. One final comment is training also needs to switch from the ongoing plan of ventilating through the cannula to accepting oxygenation is the priority and ventilation is secondary. The cannula is only a temporising measure to prevent death from hypoxia whilst working out your next step (See algorithm). NAP4 lists cannula failures, but some of them are surely jetting failures due to poor jetting plans and technique. Having a safe plan for this is essential, and we are currently publishing our latest on this.
(4) Surgical airways are a skill that one needs to learn and maintain - is there evidence that simulation and practice will improve performance in a CICV scenario? If so, what would you recommend in terms of training to maintain one's 'competence' in this skill?
There is some evidence regarding recall and hence requirements for ongoing training, one that comes to mind is Wong et al from Canada published that study showing that on a manikin it requires 5 practices at cannulae to get the technique correct… and that they recommend retraining every 6-9 months since this is the time period for deskilling.. All airway specialist do not need to attend a wet lab for training. Attending a training program that teaches a plan and techniques that are well thought out and logical is the first step. The algorithm and techniques I have developed are now taught around Australia, on NATCAT, at Airway SIG meetings, AAMRC in Melbourne, WAAG meeting and wet and dry labs here in WA, Also in Brisbane on Keith Greenland’s course and in Adelaide on Chris Acott’s courses. Also To encourage and help with ongoing refresher training we have put a set of videos on yotube to allow people to refresh their plan. Look for drambheardairway on youtube.
(5)The other scenario I have encountered in remote WA several times is the "Can't intubate, can ventilate (to some extent) - but really need a secure airway for prolonged transit, or know the airway might deteriorate due to disease etc..." This is less urgent as the sats are not crashing, but does leave one in a bit of a dilemma - will I do more harm attempting a surgical airway OR will I get into trouble if I do not secure the airway ASAP.
This is a scenario that was faced by a G.P. anaesthetist who had attended our wet lab training to return to the Kimberley region in WA and end up having to perform a surgical airway on a colleague for just this reason 3 days later. He initially (successfully) put a cannula in and then was going to convert to a melker but realised his hospital at that point did not stock the melker kit. He, having had experience of the EMST technique in the past which had not been altogether positive, went on to do a scalpel bougie, after removing the cannula and secured the airway with a 6.5 CETT. Having performed many ICU transfers in the UK, admittedly mainly by road but often very prolonged, I am of the opinion that securing a cuffed airway is of major benefit to the patient. It will always be scenario specific, but either cannula or scalpel technique can be attemped. Looking at complications, one of the major issues with cannulas, I accept, is the attaching of high pressure oxygen to the cannula to oxygenate the patient. In this scenario there is no requirement for this and you can just perform a control melker insertion without jetting or time pressure. This is the ideal scenario for inserting a melker as there is no time pressure for success and you don’t have to jet down the cannula hence avoiding barotraumas issues.
(6) Ultrasound is becoming increasingly used as an ED tool, for quick assessment in all types or resus etc. Do you see a role for rapid USS assessment of laryngeal anatomy in the presumed difficult intubation or in the midst of a CICV scenario?
I just had a paper published recently in the
European Journal of Anesthesiology on this topic. If U/S is available and you are having difficulty identifying the anterior neck airway anatomy then definitely it is worthwhile We showed that in a time pressured environment, if the trachea was not midline, U/S significantly improved performance. In this day and age of U/S becoming ubiquitous in many critical care areas this is certainly going to become more used. If nothing else ensuring the trachea is midline prior to induction, or an X marks the spot, is worthwhile if you have time.
In the 14th century, French philosopher Jean Buridan was satirised for his philosophy using the paradox of “Buridan’s Ass”. The paradox involves a donkey who is standing exactly midway between a bale of hay and a bucket of water. The donkey dies of both starvation and thirst whilst inconclusively trying to decide on a logical course of action.
How is this relevant? Well I think that the real problem with surgical airways is the “option paralysis” that takes hold when one finds oneself in a CICV scenario. If you have not thought it through or practiced a solid, reliable (in your hands) technique. Then your patient may go the way of the aforementioned donkey. I am sure there is no single, perfect surgical airway technique, but you have just gotta have a “go to” technique for when the situation arises.
