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Awake Tracheal Intubation

In this article, Dr James O’Carroll, Airway Fellow, and Dr Imran Ahmad, Consultant Anaesthetist at Guy’s Hospital and author of the Difficult Airway Society guidelines for awake tracheal intubation (ATI) in adults describe the technique of Awake Tracheal Intubation.

Introduction

Awake tracheal intubation (ATI) includes any technique in which the patient is intubated whilst awake and spontaneously breathing. A flexible bronchoscope is generally the device of choice but videolaryngoscopy (VL) is gaining in popularity, optical stylets or a front of neck airway are alternatives. ATI has a high reported success rate and is generally a safe technique because the patient maintains their own airway until they are intubated [1] [2] [3] [4].

In anticipated difficult airways, the incidence of difficult facemask ventilation is up to 22%, difficult intubation is 25%, failed intubation 0.36%, can’t intubate can’t oxygenate 0.75% and emergency surgical airway 0.12% [5]. A thorough airway assessment is essential to form a tailored airway management plan for each patient. If difficult mask ventilation and/or intubation are predicted, awake intubation is the safest approach.

Learning from NAP4

You encountered the National Audit Project of the Royal College of Anaesthetists and The Difficult Airway Society NAP4 earlier this week [6]. The learning points relating to ATI are:

• ATI with a flexible bronchoscope is an under-utilised technique.
• There were many cases in which an ATI was an obvious solution but not used.
• Failure of ATI was due to a number of factors including poor patient cooperation, inappropriate sedation, bleeding, inability to identify anatomy and airway obstruction.
• Intubation with a flexible bronchoscope after induction of anaesthesia is not always successful in patients where an awake technique is indicated.

NAP4 identified 18 cases where an awake technique for intubation may have been safer than airway management under general anaesthesia but was not performed. Generally, these patients had clinical features which suggested potential difficulty with tracheal intubation. In total, 16 of 18 could not be intubated and two patients unfortunately suffered hypoxic cardiac arrest and died. There were also 15 reports of failed awake tracheal intubation with a flexible bronchoscope. The reasons for failure included obstruction of the airway, apnoea, inability to recognise appropriate airway anatomy, anatomical distortion and airway contamination.

ATI with a flexible bronchoscope (also known as fibreoptic intubation)

To perform an awake tracheal intubation safely, preparation, good communication and teamwork are key.

Premedication

Drying the secretions can be helpful but in most situations an anti-sialogogue is not required. Intravenous glycopyrrolate can be given approximately 20 minutes before the procedure if needed.

Monitoring

Full monitoring of oxygen saturation, capnography, blood pressure and ECG should be used as per the Association of Anaesthetists of Great Britain and Ireland (AAGBI) guidelines [7], although monitoring end tidal carbon dioxide can be difficult during ATI.

Position

• Position the patient sitting upright or semi-upright
• Ensure the patient’s head is in the neutral position if possible
• Approach the patient from the front
• Ensure the scope screen, patient and operator are well aligned

Position for ATI
Patient, operator and screen positioning and set up prior to ATI

Oxygenation

High-flow nasal oxygen (HFNO) is a commonly used technique to maintain oxygenation and helps the spread of local anaesthetic when topicalising the airway. Other options include using nasal cannulae, a nasal sponge, or a Hudson mask with a hole cut out to allow for access.

use of HFNO for ATI Use of HFNO during ATI

Topicalisation

Local anaesthetic (LA) should be applied to the oropharynx and larynx for oral intubation. If using the nasal route, a vasoconstrictor and local anaesthetic should also be applied to the nasopharynx. In our hospital, we use a pre-mixed combination of phenylephrine and lidocaine (co-phenylcaine) to the nostrils via a mucosal atomising device (MAD).

We topicalise the oropharynx with 10% lidocaine spray, up to a maximum dose of 9mg/kg, but much lower doses are usually needed. Topicalisation should be tested e.g. with a Yankauer sucker. If the patient reacts then more lidocaine spray should be applied.

MAD device
Nasal sponge MAD and malleable MAD bent to allow topicalisation of the vocal cords.

Sedation

Although not compulsory, sedation helps with patient compliance and comfort. Remifentanil given as a target-controlled infusion is often used in UK practice. Ideally a separate practitioner should be responsible for sedating the patient as the commonest complications of ATI, such as apnoea, airway obstruction and desaturation occur due to over-sedation.

Tracheal Tubes

A flexible nasal or a reinforced tracheal tube are used for nasal intubations. A small tube (6-6.5mm internal diameter) reduces the risk of trauma and impingement. A reinforced tube is best for oral intubations. When using a VL, a bougie or stylet may be needed to assist with tube placement.

Oral or Nasal Route?

When using a flexible bronchoscope the nasal route is more comfortable for the patient. The choice of oral or nasal route depends on patient factors, pathology and surgical procedure, this should be discussed with the surgeon at the team brief.

Once the tracheal tube is in place its position must be confirmed with a two-point check 1 - capnography and 2 - viewing the tracheal lumen with the bronchoscope.

Awake Videolaryngoscopic Intubation

Awake videolaryngoscopic intubation may be easier, faster and safer to perform than flexible bronchoscopy because most anaesthetists are familiar with laryngoscopy. Patient preparation should be the same as the oral bronchoscopic technique with thorough topicalisation of the airway. Limited mouth opening is an obvious restriction to its use.

Use of a videolaryngoscope in an awake patient

If there is significant supraglottic swelling and passing of the bronchoscope causes obstruction of the airway (the ‘cork in bottle’ effect) an awake VL technique may be better tolerated.

Fibreoptic assisted awake VL - A common problem with VL is that even with a good view of the glottis it may not be possible to pass the tube into the trachea. A second operator can guide a flexible bronchoscope into the trachea and then railroad the tube, as when using a bougie [8].

Awake tracheostomy under Local Anaesthesia

If flexible bronchoscopic or videolaryngoscopic techniques are not possible a surgical tracheostomy under local anaesthesia is an option. The most common indication is a tumour involving the airway. This relies on a patient who is able to be compliant and lie flat for the duration of the procedure. This technique should only be performed by a skilled surgeon and only when all other options have been excluded.

Tracheostomy in an awake patient

Supraglottic Airway Device

Supraglottic airway devices can be used in an awake patient to either provide a patent airway, or as a channel to guide the flexible bronchoscope into the trachea.

Insertion of supraglottic device in an awake patient

Please share your experiences of ATI in the discussion below. What is your preferred technique Have you used videolaryngoscopy for awake intubation? What went well? What problems did you encounter? As this is a public open forum, please be considerate of patient confidentiality.

In the next step we will have an opportunity to watch Dr James O’Carroll and Dr Ed Roberts perform an awake tracheal intubation, before we go on to review the recently published DAS ATI Guidelines.

References

  1. Alhomary M, Ramadan E, Curran E, Walsh SR. Videolaryngoscopy vs. fibreoptic bronchoscopy for awake tracheal intubation: a systematic review and meta-analysis. Anaesthesia 2018; 73: 1151–1161.

  2. El-Boghdadly K, Onwochei DN, Cuddihy J, et al. A prospective cohort study of awake fibreoptic intubation practice at a tertiary centre. Anaesthesia 2017; 72: 694–703.

  3. Joseph TT, Gal JS, DeMaria SJ, Lin H-M, Levine AI, Hyman JB. A Retrospective Study of Success, Failure, and Time Needed to Perform Awake Intubation. Anesthesiology 2016; 125: 105–114.

  4. Law JA, Morris IR, Brousseau PA, de la Ronde S, Milne AD. The incidence, success rate, and complications of awake tracheal intubation in 1,554 patients over 12 years: an historical cohort study. Canadian Journal of Anaesthesia = Journal Canadien d’anesthesie 2015; 62: 736–744.

  5. Nørskov AK, Wetterslev J, Rosenstock C V., et al. Prediction of difficult mask ventilation using a systematic assessment of risk factors vs. existing practice – a cluster randomised clinical trial in 94,006 patients. Anaesthesia 2017; 72: 296–308.

  6. Cook TM, Woodall NM, Frerk CM. 4th National Audit Project of the Royal College of Anaesthetists and The Difficult Airway Society. Cook T, Woodall N, Frerk C, eds. British Journal of Anaesthesia 2011; 106: 617–31

  7. Checketts, M. R., Alladi, R., Ferguson, K., Gemmell, L., Handy, J. M., Klein, A. Association of Anaesthetists of Great Britain and Ireland (2016). Anaesthesia, 71(1), 85–93. doi:10.1111/anae.13316

  8. T. G. Saunders M. L. Gibbins C. A. Seller F. E. Kelly T. M. Cook. Videolaryngoscope‐assisted flexible intubation tracheal tube exchange in a patient with a difficult airway. Anaesthesia Reports. April 2017

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Airway Matters

UCL (University College London)