FRCA Notes

Difficult Extubation

An SAQ on difficult extubation appeared in 2019 (64% pass rate), based around the DAS guidelines.

Examiner feedback from the question was fairly non-specific, while the curriculum is also light on requirements for extubation beyond demonstrating 'appropriate management of extubation'.

Resources

  • Tracheal extubation is a critical step and, although the majority of problems at extubation are minor, a small number have serious consequences

  • Respiratory complications at extubation are common
    • 1/3rd of reported cases during NAP4 were major airway complications during emergence/in recovery
    • More common in patients who are obese or those with OSA

Airway obstruction

  • The primary cause of airway complications at the end of anaesthesia; may occur in up to 20%
  • There are a host of potential causes, such as:
    • Laryngospasm (17-25%)
    • Inadequate reversal of NMBA (up to 10%); up to 41% of patients still arrive in recovery with a ToF ratio <0.9
    • Bronchospasm (1%)
    • Reduced pharyngeal tone e.g. obese/OSA, residual anaesthesia, excessive opioids
    • Stridor
    • Obstruction of ETT or tracheostomy e.g. biting, secretions
    • Retained throat pack
    • Laryngeal compromise
      • Progressive oedema and glottic dysfunction leading to stridor and orthopnoea
      • Can occur following surgical intervention (e.g. drainage of head and neck abscess) or be due to other factors (e.g. prolonged Trendelenburg positioning)

Altered airway reflexes

  • Exaggerated reflexes may cause coughing or bucking (18-66%) or breath-holding (13-20%)

  • Dysfunctional reflexes can causes paradoxical vocal cause motion
    • Paradoxical vocal cord motion (i.e. adduction in inspiration) is more common in young females and the emotionally distressed
    • It can cause stridor; it is relieved by anxiolytic/sedation/opioid agents

  • Reduced reflexes may lead to aspiration
    • The risk of aspiration is increased by forceful inspiratory effort (negative intrathoracic pressure opens oesophagus) or forceful PPV (distends stomach)
    • E.g. deep extubation

Airway injury

  • Airway injury may be direct or indirect

  • Direct injury is usually:
    • Surgical e.g.ENT surgery, OMFS surgery or other surgery on the head & neck area
    • Anaesthetic e.g. laryngoscopy, effects of airway devices or adjuncts such as NG tubes, TOE

  • Indirect injury describes haematoma, tissue oedema or other swelling (e.g. reduced lymphatic drainage) as a consequence of surgery

Respiratory

  • Hypoxia (up to 24%)

  • Post-operative pulmonary complications

  • Post-obstructive pulmonary oedema (0.1%)
    • 10% of all anaesthesia-related airway complications in NAP4
    • Due to forced inspiration against an occluded airway or closed glottis
    • Typically in young adults attempting to inhale against a laryngospastic glottis or an ETT on which they are biting
    • Management is largely similar to cardiogenic pulmonary oedema; oxygen, CPAP ± diuretics

Cardiovascular

  • Sympathetic activation e.g. hypertension, tachycardia and raised CVP (10%)
  • Dysrhythmia (7%)
  • Bleeding e.g. post-thyroidectomy, post-tonsillectomy, which may cause airway obstruction

Other

  • Neurological e.g. raised ICP, raised IOP
  • Infection e.g. mediastinitis following treatment for deep airway or head and neck infections

General

  • Obesity
  • OSA
  • Risk of aspiration
  • Pre-operative airway obstruction
  • Instability of the respiratory, cardiovascular, neurological or metabolic systems

Surgical factors

  • Head and neck surgery inc. ENT, OMFS, cervical spine surgery
  • Steep Trendelenburg positioning
  • Prolonged surgery
  • Difficult airway access e.g. presence of implants, halo frames

Anaesthetic factors

  • Difficult airway management, including facemask ventilation or intubation, at induction
  • Airway trauma, bleeding or other oedema
  • Use of drugs which may compromise airway patency e.g. NMBA, opioids
  • Inability to oxygenate appropriately e.g. HFNO and NIV contra-indicated following trans-sphenoidal pituitary surgery

  • Extubation is an elective process, which should be planned and executed
  • There is no 'one-size fits all' model for extubation, although the common goals are:
    • Ensure uninterrupted oxygen delivery
    • Avoid airway stimulation
    • Back-up plan permitting ventilation and re-intubation without difficulty should extubation fail
  • The ultimate choice of technique will depend on the patient and their pathology

General steps

  • In general, all (difficult) extubation strategies have in common:
    • Adequate airway equipment available for re-intubation, including HFNO
    • Anaesthetic drugs drawn up for re-intubation, including temporising measures e.g. adrenaline nebulisers
    • Verbalised management strategy in case of failed extubation
    • Extubation in a safe environment (typically theatre) with adequate staff around (ODP, ENT surgeons)
    • An appropriate period of monitoring folowing extubation

  • Following the DAS basic extubation algorithm leads you to one of five possible steps:
    • Low-risk patients can be:
      1. Extubated awake
      2. Extubated deep

    • High-risk patients can be extubated awake (if appropriate), or can:
      1. Be extubated using advanced airway techniques
        • Deep exchange of their endotracheal tube for a supraglottic device
        • Extubation with a remifentanil infusion still running
        • Extubation over an airway exchange catheter
      2. Have extubation postponed
      3. Undergo tracheostomy

  • One should extubate the patient either fully awake or when deeply anaesthetised, not in intermediate planes of anaesthesia

Awake extubation

  • Benefits from a spontaneously breathing in whom airway reflexes has returned, who is likely to be able to maintain and protect their airway in an ongoing fashion
  • The technique may result in adverse respiratory (coughing, straining, bucking), cardiovascular (sympathetic activation i.e. hypertension, tachycardia, venous engorgement) or other sequelae
  • If these sequelae are undesirable and/or unable to be managed by other means, then consider deep extubation

Deep extubation

  • May be desirable in various head & neck surgeries inc. ENT, OMFS, neurosurgery
  • Benefits from avoiding the aforementioned ill-effects of airway irritation caused by and endotracheal tube in an awake patient
  • Not appropriate for those at risk of aspiration, with anticipated/known difficult bag-mask ventilation or re-intubation

  • It is technically more challenging, as it requires establishment of spontaneously ventilation but with adequate depth of anaesthesia
  • Suctioning of the larynx under direct vision is mandatory to prevent tracheal soiling
  • Once the tube is removed, airway maintaining manoeuvres and adjuncts may still be required
  • Also requires ongoing monitoring until recovery from the full effects of anaesthesia to ensure no further interventions are needed

LMA Exchange

  • The ETT is exchanged for a SAD after appropriate suctioning of the airway under direct vision
  • Benefits from:
    • Smoother emergence from anaesthesia
    • Reduced coughing, breath-holding and bucking
    • Reduced haemodynamic changes around extubation
    • A degree of protection of the larynx against secretions with the SAD in situ
  • Consider checking the correct seating of the SAD at the laryngeal inlet with a flexible bronchoscope before weaning anaesthesia
  • Not appropriate for those at risk of aspiration, with anticipated difficult bag-mask ventilation or re-intubation

Remifentanil

  • Extubation with an ongoing remifentanil infusion
  • Requires careful dose titration to achieve spontaneous ventilation e.g. Ce 1-2ng/ml
  • The ETT is removed once the awake patient obeys commands and demonstrates adequate ventilation
  • Benefits from:
    • Obtunded coughing and straining
    • Reduced haemodynamic changes
    • Facilitation of awake extubation

Airway Exchange Catheter

  • The AEC is a long, hollow, narrow, semi-rigid bougie which can be placed in the trachea through the ETT
  • The AEC is inserted with the tip at the level of the mid-trachea (i.e. above the carina and never more than 25cm from the lips)
  • The ETT is then removed; the AEC left in situ and taped to the patient

  • Benefits from:
    • Functioning as a bougie to facilitate re-intubation if necessary
    • Ability to generate capnography and therefore a marker of ventilation
    • Theoretical ability to provide oxygenation
  • However, should avoid administering oxygen due to concerns re: barotrauma and pneumothorax if there is impeded expiration/gas outflow

  • Well-tolerated by the awake patient
  • Can be left in for up to 72hrs
  • In general removed as soon as the complications which may lead to the need for re-intubation have been ruled out
  • Requires monitoring in an appropriate high-care area

Keep asleep and transfer to ICU

  • Allows time for underlying issues to be addressed
  • Airway remains at risk due to:
    • Tube obstruction e.g. from secretions
    • Tube displacement e.g. during transfer, during turns
  • Can lead to other complications such as:
    • Prolonged ventilation may lead to HAP/VAP
    • Weakness from prolonged ventilation

Tracheostomy

  • May be performed electively or in an emergency setting
  • Multiple benefits but not insignificant risk (see separate page on tracheostomies)