This skill station covers:
Extubation guidelines, equipment and strategies
Staged extubation and Airway exchange catheters
This section covers how we assess patients for extubation and airway device exchange, and how we perform these procedures safely.
Extubation and airway exchange are covered in the same module because the techniques for airway device exchange and high-risk extubation have many similarities.
Extubation – The Risk Paradox
Tracheal extubation carries a similar risk profile to tracheal intubation but receives much less attention.
In NAP 4, about one third of anaesthesia incidents occurred around extubation and recovery. Most were due to airway obstruction: laryngospasm, airway swelling, bleeding and device occlusion by biting.
The diagnosis of obstruction was often delayed, resulting in mortality and morbidity.
Decreased Airway Reflexes
Increased Airway Reflexes
Airway Injury and Swelling
Airway injury may not become evident until extubation is attempted.
The year after NAP4, the Difficult Airway Society (DAS) published their extubation guideline. They are based mainly on expert opinion, as there is very little trial evidence.
They are really designed for adult peri-operative care and not critical care patients; however, the same basic principles apply to all patients.
The Basic algorithm outlines planning and preparation, followed by risk assessment.
The Basic algorithm
Risk Assessment
- History, examination and investigations are required for risk assessment.
- DAS divides risk factors into ‘Airway’ and ‘General’ (see Basic algorithm)
- It can also be useful to think of these risk factors in terms of anatomical and physiological difficulties (see Airway Assessment module – link)
- The DAS Low risk and At risk algorithms to guide clinicians towards an extubation strategy.
Awake or asleep?
A major difference between the Low risk and At risk algorithms is that the Low risk algorithm includes the option to extubate patients while asleep (‘deep extubation’).
Deep extubation is more commonly performed in the operating theatre (OT), the perceived benefits being decreased coughing and haemodynamic stability.
Critically ill patients will usually be designated as At risk and are therefore extubated awake.
Sedative and/or analgesic drugs might be of benefit in some critically ill patients to control agitation or maintain stable blood pressure and/or intracranial pressure.
Short acting agents are preferable, such as low dose propofol, remifentanil, or dexmedetomidine.
The extubation strategy should ideally be considered prior to intubation.
It should include a plan for the timing and technique of extubation, and the disposition and ongoing care of the patient.
Patients should be extubated in clinical areas with full monitoring and emergency equipment. ED resuscitation areas and ICU have these facilities.
If anaesthetists are involved in extubation, they may prefer to take the patient to OT.
Consider whether a senior anaesthetist or ENT surgeon should be present or immediately available.
Extubation is a team decision and a team activity. Involve nursing staff. In ICU patients, involve allied health staff (Speech Pathology and Physiotherapy).
Head up positioning helps with coughing, secretion management and to increase safe apnoea time in case of problems with extubation ongoing airway management.
- Pre-extubation – most patients should receive 100% oxygen via the ETT to increase safe apnoea time.
- Post extubation – oxygen therapy should be judged on a per-patient basis to avoid wastage of equipment: most patients can safely be extubated onto room air or standard nasal cannulas.
- High flow oxygen should be humidified.
- Consider steroids patients who are At risk due to airway risk factors (see below)
- Ensure neuromuscular blockade is reversed/inactive.
- Consider anti-sialagogue.
- Analgesia and sedative drugs.
- Full monitoring including waveform capnography.
- Resuscitation equipment.
- Airway Trolley.
- Equipment for advanced techniques for At risk patients.
- Wire cutters (wired jaw), clip removers (neck surgery).
- Deep extubation.
- Awake extubation.
- Airway exchange catheter or staged extubation kit (see Advanced Extubation Techniques below).
- Monitoring.
- Location.
- Re-intubation plans ABCD.
Steroids to prevent post-extubation stridor
- Patients with airway risk factors (see Pathophysiology of failed extubation – Airway injury and swelling above).
- Patients who fail a cuff-leak test.
- Patients with confirmed injury/swelling on nasendoscopy.
There is good evidence that steroids can decrease the incidence of post-extubation stridor and re-intubation.
Multiple doses, equivalent to 100mg hydrocortisone four times daily, are preferable to single doses.
Standard Approach
- Head up position.
- Aspirate nasogastric tube (note that this does not reliably empty the stomach completely).
- Suction oropharynx, preferably under direct vision.
- Administer 100% O2 via tracheal tube.
- Apply positive pressure, deflate cuff and remove tube at end inspiration.
- Administer oxygen as required.
- Patients must be cared for in the OT, recovery area, ED resuscitation bay, HDU or ICU. Monitoring should include ECG, BP, SpO2 and waveform capnography, and there should be immediate availability of clinicians with advanced airway skills.
- Nursing staff must be trained to monitor for clinical signs that predict the need for re-intubation: hoarse voice, cough, difficulty swallowing, drooling, stridor, orthopnoea. Patients should also be closely watched for bleeding; into the airway, into drains or into an expanding haematoma.
- Only one intervention has been found to be beneficial in the immediate treatment of the patient with post-extubation stridor. Nebulised adrenaline (3-5mls of 1:1000 solution, nebulised with oxygen at 6L/min) can relieve the situation, but its effect may only be temporary. This treatment should be administered while senior help is sought, so a thorough airway assessment can be performed and a decision made about ongoing airway management.
If it all seems too hard…
It is important to remember that extubation can always be delayed.
Admitting the patient to the ICU for further assessment is prudent if there is any doubt about the airway.
The patient can also undergo elective tracheostomy if problems with the airway are thought to be insurmountable in the short term.
The DAS guideline refers to the “LMA technique”. This is an advanced technique used in anaesthesia and is not covered on the CCAM course.
The two main techniques covered on CCAM are the Airway Exchange Catheter (AEC) and the Staged Extubation Kit.
Note: AECs are also used for the exchange of one airway device for another (as the name implies!). These techniques are also covered in this section.
Airway Exchange Catheters for Staged Extubation
Airway exchange catheters (AECs) are long catheters, originally designed for changing one airway device (SAD or ETT) for another, that can be used for staged extubation.
The most used device is the Cook™ AEC.
Cook™ Airway Exchange Catheter
Cook™ Airway Exchange Catheter
- Size range 5-19 Fr, 50 – 100cm long
- Most have hollow lumen
- O2 delivery by insufflation (constant flow) or manual ventilation
- 15mm and Luer-lock Rapi-Fit™ connectors provided.
- High-pressure wall/cylinder O2 is NOT RECOMMENDED
For staged extubation, the AEC is inserted through the ETT and positioned with the tip just above the carina. The patient is then extubated, leaving the AEC in situ (to facilitate re-intubation), until the patient is deemed safe.
The duration of use is highly variable, and the device may or may not be used to deliver oxygen during this time.
It is important to note that Cook™ have stated that their AECs are designed for airway exchange only and are not designed to be left in the airway for long periods. However, this ‘off label’ practice is relatively commonplace and seems to be well tolerated by patients.
The Evidence
A large case series has retrospectively analysed the practice of staged extubation in 354 high-risk patients. On initial examination, the study seems to suggest that the AEC is a useful adjunct.
- 14% required re-intubation using the AEC, with a high success rate (92%) and few complications
- 86% were deemed safe and the AEC was removed. Of these, 12% required re-intubation, which was difficult – more attempts and four surgical airways.
Further analysis of this paper questions the usefulness of the AEC.
- 41% of the patients who were deemed safe enough for their AECs to be removed required re-intubation – so the assumption that these patients would tolerate extubation was incorrect nearly half of the time.
- It may be that the AECs were removed too soon – the average duration of use was 3.9 hours, and it is known that laryngeal oedema can occur up to 8 hours post extubation.
- The AEC itself might also have an effect – by narrowing the airway lumen, causing trauma and inflammation, and precipitating cough, laryngeal spasm and stridor.
High pressure oxygen and the AEC
It is possible to deliver high-pressure oxygen via AECs – up to 400kPa if using unrestricted wall oxygen.
The use of high-pressure O2 is therefore risky and should be avoided.
In 2010, there were two deaths associated with the use of AECs:
Case 1:
- AEC used to exchange SAD for ETT after failed intubation.
- During exchange, O2 insufflated via AEC at 15L/min.
- This caused the rupture of the right main bronchus, with migration of the catheter through the lung and out into the chest wall.
- Massive surgical emphysema, barotrauma, cardiac arrest and death.
Case 2:
- Young patient post maxillofacial surgery, with elastic band inter-maxillary fixation.
- Sent to recovery area with AEC in situ, with O2 insufflated at 5L/min, to facilitate re-intubation of problems.
- Banding reduced his mouth opening and ability to exhale.
- Tension pneumothorax, cardiac arrest and death.
These deaths were followed in 2011 by a review of the literature which revealed a worryingly high incidence of barotrauma associated with the delivery of oxygen via AECs. Of the 18 cases of barotrauma identified, high pressure ventilation was used in 16.
CCAM recommends that O2 should only be delivered via AECs and AICs using the 15mm connector attached to a bag-valve apparatus, with constant flow oxygen or careful manual ventilation.
Cook™ Staged Extubation Set
Cook™ Staged Extubation Set
- Flexible wire (145cm, 0.9mm diameter)
- Soft, blunt tipped re0intubation catheter (83cm, 14 Fr)
- Wire and catheter have depth markings
- 15mm and Luer-lock Rapi-Fit™ connectors provided.
- High-pressure wall/cylinder O2 is NOT RECOMMENDED
The Cook™ Staged Extubation Set has been designed with the above concerns in mind.
In this technique, a soft-tipped wire is inserted through the tracheal tube, which is then removed. The wire is narrower and less irritating than an AEC and can theoretically be left in for a long period. Should the patient require re-intubation, a catheter with a blunt, atraumatic tip is inserted over the guidewire to stiffen the whole apparatus so that a tracheal tube can be introduced.
The catheter comes with Rapi-Fit™ connectors to allow oxygen delivery during the re-intubation attempt.
Both the AEC and the Aintree Intubation Catheter (AIC) can be used for airway exchange.
The AIC has a larger internal diameter to allow placement using a bronchoscope. It is therefore easier to confirm positioning just above the carina.
Great care must be taken with both devices that their distal position does not change when the initial device is removed and the exchange device placed. Using a laryngoscope to facilitate passage of the exchange device is recommended.
Hold-up of a replacement ETT at the level of the vocal cords can be avoided by a 90° left turn (also see Plan A section)
Aintree Intubating Catheter™
Aintree Intubating Catheter™
- 56 cm long – fits over standard-length bronchoscope (60 cm)
- Internal diameter 4.7 mm – for use with slim bronchoscope
- Outer diameter 6.5 mm – can be used to exchange devices with ID ≥ 7.0mm
Problem: AIC has limited length
- Length of AIC limited to length of bronchoscope.
- Removing initial device can be tricky.
- Solution: insert AEC through AIC before removing first device.
- Increased overall length helps removal of first device and insertion of new device.
Problem: AEC is narrow gauge
- Narrow gauge of AEC can cause hold up of tubes.
- This is dues to flexibility of AEC and large step between AEC and tube.
- Solution: railroad AIC over AEC to decrease flexibility and decrease step.