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Awake Tracheal Intubation – DAS Guidelines
Dr Imran Ahmad discussed the new DAS guidelines on tracheal intubation .
So there are many recommendations throughout the ATI guidelines paper. But we have eight key recommendations that we would like to focus on at the beginning of the paper. The first one is that in the presence of any predictors of difficult intubation, an awake tracheal intubation should be considered. And the reason for this is that, we are aware that in the case of predicted difficult airways, there is a higher chance of difficulty with face mask ventilation with supraglottic airway positioning and placement and ventilation via supraglottic airway and also direct laryngoscopy and intubation. In which case, if you’re predicting the airway to be difficult, you should try and avoid those risks and complications by doing an awake tracheal intubation.
We’re also aware that these risks are lower in patients having the awake tracheal intubation. And so it makes sense that in the presence of difficult intubation predictions, that an awake tracheal intubation must be considered. OK. And the key recommendation that we like to make is the use of a cognitive aid, such as a checklist. These guidelines are primarily aimed at people who don’t do awake intubations very often. And therefore, we know, and we thought as a group, that having a cognitive aid such as a checklist, would actually remind those of us who don’t do them regularly, of the key features and equipment that they may require to do an awake intubation.
So we have to created a checklist, very similar to the WHO checklist, which practitioners you can go through prior to performing the awake intubation to make sure they have the correct set up, the correct equipment, the correct technical team available, and that everybody knows what their roles are, and what’s required of them, and what to do in the event of a failed intubation. So we’ve created the checklist and you are able to download from the website. And it’s part of the paper as well. The third recommendation is regarding oxygenation. We looked at all the various oxygenation techniques during awake tracheal intubation. And the key recommendation here is, you must give supplementary oxygen during the awake tracheal intubation.
The reason for this is that this patient, by definition, is an anticipated difficult airway, and you want to make sure they’re pre-oxygenated in the event of any complications or any problems you may have during the intubation process. So we highly recommend giving supplementary oxygen during the procedure. In terms of the root of oxygenation, we feel that high flow nasal oxygenation is the technique of choice. There is one or two papers suggesting that that the failure or the desaturation rate is very low if you are giving high flow nasal oxygenation during the awake tracheal intubation. And therefore, this is the technique that we have opted to recommend. Patients tolerate it well.
You are able to give up to 70 litres a minute of humidified warmed oxygen. And if the patient does become apnoeic, which we hope it doesn’t, because you’ll minimise your sedation techniques, or you’ll minimise the amount of sedation you’re delivering.
Then you still have some oxygen reserve available. And actually, at the moment, this is the only technical way of giving 100% oxygen during an awake intubation procedure. And once the patient has been topicalized, this must be tested in an atraumatic way. And once you are happy that the patient is properly topicalized, then, and only then, should you start the procedure. If you feel the patient is not adequately topicalized, then some more local anaesthetic should be applied. Again, up to the maximum 9 mg/kg dose. The next recommendation that we have made is regarding sedation. Now, if sedation is used, then this should be minimal.
You certainly don’t want patients to be oversedated, because oversedation is one of the most common complications of awake tracheal intubation. And you can run into to serious troubles if the patient becomes oversedated in terms of airway loss, becoming unresponsive, and becoming hypoxic. And therefore, minimal sedation it was because what we recommend, if at all. Awake intubations can be done with no sedation whatsoever. But some patients may benefit from sedation because they will tolerate the procedure better, and it may give them some element of amnesia.
If sedation is going to be given, then we recommend ideally it is to be given by a separate anaesthetist or somebody else who is solely responsible for giving the sedation whilst a second anaesthetist is responsible for actually doing the awake intubation. We recommend a single agent looking at the evidence. This agent happens to be remifentanil, a remifentanil infusion, up to a maximum of about 3 ng/ml TCI dose. If a second person is available, you may add a second sedation agent, usually midazolam, a very small dose, maybe 0.5 to 1mg dose just for an element of amnesia. But the key thing here is that sedation is not essential.
But if it is given, it must be minimal sedation to allow the patient to tolerate the procedure. And one other key thing here is that sedation must never be used as an alternative to adequate topicalization. That must be key. But sedation can be used just to help facilitate the procedure. The sixth key recommendation of number of attempts at performing awake tracheal intubation. You certainly don’t want to be having numerous attempts. That has a risk of trauma and spiralling out of control and resulting in bleeding or airway obstruction. So we recommend that you have three attempts. And each attempt must be better than the previous attempt.
Something must have changed from your initial attempt to your next attempts to increase the success rate. If you have had three attempts and you’re still unsuccessful, then we reserve a fourth attempt for an expert, someone more experienced who may be on their way to help. If that person is not available, then we would recommend you stop at three attempts because this is the safe thing to do, and you hopefully have a spontaneously breathing patient who you can now reevaluate and decide on what the best course of action is. But our sixth recommendation here is that you limit your number of attempts to three plus one reserved for an expert.
Now having had those three attempts, and you’ve still been unsuccessful in intubating the patient, then we have an algorithm that we’ve designed for the unsuccessful awake tracheal intubation. The most important thing is to call for help, because you may run into trouble if you continue on your own. And the default position here is to postpone the procedure and just allow the patient to breath spontaneously and then have a think of what you need to do. There are certain circumstances where this is not the option, or this is not an option. And you will be unable to postpone, and you must proceed. And if this is the case, then you really only have two options here.
Either you opt for a high risk general anaesthesia intubation technique, in which case you would need to make sure you have appropriate assistance and equipment available. Right. Anaesthesia should only be induced after a two point check confirms the correct position of endotracheal tube. This is our seventh recommendation. What we like to recommend here, is that you use two techniques to ensure the correct position of the tube in the trachea. The first one is capnography, and the second one is visualising the tube in the trachea, which can either be using the flexible bronchoscope technique, where as you withdraw the flexible bronchoscope you can visualise the endotracheal tube in the trachea.
Or if you’re using the videolaryngoscopy technique, you can see the endotracheal tube entering the trachea by the doctors through the, past the vocal cords. The eighth a recommendation is regarding training and support of performing awake tracheal intubation. We feel that all departments should support their anaesthetists to attain and maintain their skills in awake tracheal intubations. This can only be done if this practise is encouraged and performed when indicated. So we highly recommend that all departments allow anaesthetists to perform the technique. So the guidelines there are various ways, we’ve incorporated elements of human factors techniques, to improve and make safer the awake tracheal intubation procedure.
For example, cognitive aids - we’ve developed a checklist which allows the anaesthetist to tick a very simple tick box checklist that allows anaesthetists to make sure they have appropriate equipment and staff available prior to commencing awake tracheal intubation. We also have a cognitive aid which looks rather like a propeller, which has four key elements to it. In the acronym STOP, which involves Sedation, Topicalization, Oxygenation, and then the actual Procedure itself. And again, if you think about those four key elements, and you successfully plan and prepare for those four key elements, you’re much more likely to successfully achieve an awake tracheal intubation, whether it be using the flexible bronchoscope or a videolaryngoscope. OK.
So the checklist incorporates many things, including the location of where you’re performing the awake tracheal intubation, and which staff are present. And you would always need an anaesthetist and an anaesthetic assistant. You may require a second anaesthetist who would help with the sedation aspects of the awake tracheal intubation. You may require surgeons to be present, either immediately present, scrubbed, and ready, or immediately available if required. So communicating that prior to performing the procedure is important. And that’s part of what the checklist allows you to think about. Another aspect of the checklist is a team briefing.
And every member of the team involved in the awake intubation must know what their role is and what to do in the event of any complications or any problems. So the anaesthetic nurse must know where the equipment is that is required, first of all immediately, but also in the event of any failure or any complications. The anaesthetist performing the procedure should know where the equipment is and what equipment is required. Hopefully, they will have a second anaesthetist available for providing sedation. And that anaesthetist must be aware of the doses being given and any infusion pumps that are being used. And also the surgeon must be aware that the procedure is being done, whether they’re required or not.
And if they’re immediately required, then they should be scrubbed and ready in theatre with the appropriate equipment available, and ready to perform the surgical airway if that’s deemed necessary. Other human factor elements that we focus on are communication. Communication between the anaesthetist and the anaesthetic assistant, between the anaesthetist and the theatre team, and the anaesthetist and the surgeon. Often, if it’s and anticipated difficult airway, you may require a surgeon to be scrubbed and ready. And communicating that with the team and the surgeon is very important. We’re well aware that workspace ergonomics have an impact on the outcome of procedures such as awake tracheal intubation.
There’s no real recommendation or evidence to show whether you stand behind the patient or in front of the patient or if the patient is sitting or lying has any benefit to one or the other in a successful outcome. So we’ve therefore given guidance on performing the procedure from either behind the patient or facing the patient from in front. And within the guidelines, we’ve developed or we’ve created some diagrams to allow you to see optimum ergonomic positioning of yourself, the operator, of the patients, of your assistant, of the second anaesthetist, the monitoring, and the fibrescope and the airway trolleys.
So we feel that to have them set up in an ergonomic manner will allow you to safely perform the procedure in a more comfortable way. Not only for the operator, but also for the patient. OK, we know that complications do occur, even during an awake tracheal intubation technique. Case studies have shown this to be up to 18%, but this depends on what you reported as a complication. Complications usually occur due to inadequate sedation, oxygenation, topicalization, or performance aspects. And you must think of why the procedure is failing or why the complication is occurring, and address that complication. For example, if the patient is oversedated then the sedation should be stopped or reversed.
If the patient is becoming hypoxic, then either increase the oxygen concentration, or actually the technique of delivering oxygen. Or if there is inadequate topicalization, then more local anaesthetic should be applied. So looking at the reason why the awake intubation technique is failing, and then addressing that using the STOP acronym to directly address the cause of the complication is what we recommend in the guidelines.
In this video, Dr Imran Ahmad, as one of the Guidelines authors, takes a few moments out of his operating list to discuss the key recommendations from the DAS Guidelines on Awake Tracheal Intubation.
As we have seen, awake tracheal intubation (ATI) is a safe technique for patients with difficult airways. Despite this, we know that it is used in as few as 0.2% of all intubations in the UK. The traditional approach, using a flexible bronchoscope, is an advanced technique which requires training and regular practice to maintain skills. The equipment is costly and relatively difficult to maintain. As most clinicians do not perform ATI on a regular basis, they may feel reluctant to use the technique even when it is indicated.
These guidelines aim to demystify awake intubation and lower the threshold for using the technique in patients with difficult airways. They provide clear guidance on decision making, preparation and performance of the commonly used techniques. They include advice on oxygenation, sedation, topicalisation, set up and performance, how to adapt the technique according to the patient circumstances such as the critically ill, obstetric and obese and what to do if difficulties are encountered.
The full publication [1] includes visual aids to help with human factors and ergonomics, here are some examples:
Cognitive aid: Sedation-Topicalisation-Oxygenation-Procedure (STOP)
HFNO: high-flow nasal oxygen. LA: local anaesthetic. FB: flexible bronchoscopy. MAD: mucosal atomising device. TCI: target-controlled infusion. Ce: effect-site concentration. VL: videolaryngoscopy. ©Difficult Airway Society 2019.
Examples of ergonomics for awake tracheal intubation
©Difficult Airway Society 2019. (a) Awake tracheal intubation performed with the operator positioned facing the patient who is in a sitting up position. (b) Awake tracheal intubation performed with the operator positioned behind the supine/semi-recumbent patient. This figure forms part of the Difficult Airway Society guidelines for ATI in adults and should be used in conjunction with the text below.
The primary operator should have a direct line of sight of the patient, video monitor and patient monitor, as well as immediate access to infusion pumps, anaesthetic machine, suction and oxygen delivery device.
If a second anaesthetist is present, they should be positioned with a direct line of sight of the patient and have immediate access to infusion pumps, as well as be able to access all other equipment.
The anaesthetic assistant’s primary position should be with immediate access to the airway trolley, and in proximity to the operator.
An ATI checklist is also provided
©Difficult Airway Society 2019
How confident are you at performing or assisting in an awake tracheal intubation? Do you use a checklist before you start? Do you have the anaesthetic room laid out as suggested above? Do you think you might try this next time? Please do discuss this with your fellow learners before going onto the next step, exploring jet ventilation.
References
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