Weaning and extubation

Surgical approach (if applicable)

• Not a surgical operation. Relevant procedural/ICU workflow:
  • Daily sedation hold / spontaneous awakening trial (SAT) + spontaneous breathing trial (SBT)
  • Assess readiness, plan extubation strategy (standard vs high-risk), prepare equipment and staff
  • Extubate to appropriate support (face mask, HFNO, NIV, CPAP), monitor closely, manage complications
  • If failure: treat reversible causes, re-intubate early if needed; consider tracheostomy if prolonged wean

Anaesthetic management (if applicable)

• Context: ICU weaning/extubation or end-of-anaesthetic extubation (the principles overlap).
• Type of anaesthesia:
  • ICU: sedation/analgesia titration rather than intra-op anaesthesia
  • Theatre: GA with ETT/SGA; extubation at end of case
• Airway device:
  • Consider airway exchange catheter for high-risk extubation; consider staged extubation
• Duration:
  • ICU: days–weeks; theatre: minutes at end of surgery
• How painful:
  • Inadequate analgesia → tachypnoea, poor cough, splinting, atelectasis, extubation failure
• Key anaesthetic/ICU priorities:

Definitions and aims

• Weaning: gradual reduction of ventilatory support until patient sustains adequate spontaneous ventilation.
• Extubation: removal of ETT when airway protection and ventilation/oxygenation are adequate.
• Aims: minimise ventilator-associated harm (VAP, diaphragm dysfunction, delirium) while avoiding premature extubation and re-intubation.

Physiology relevant to weaning

• Work of breathing increases when support is reduced: resistive (airway resistance, secretions, bronchospasm) + elastic (↓ compliance: oedema, atelectasis, ARDS) loads.
• Cardiovascular: transition to spontaneous breathing increases venous return and LV afterload (more negative intrathoracic pressure) → may precipitate pulmonary oedema/ischaemia in vulnerable patients.
• Respiratory muscle function: diaphragm disuse atrophy with controlled ventilation; fatigue if load exceeds capacity during SBT.
• Gas exchange: loss of PEEP/mean airway pressure can worsen V/Q mismatch and atelectasis; oxygenation may drop post-extubation.

Readiness to wean: prerequisites (ICU)

• Underlying cause improving and no new major instability.
• Oxygenation acceptable on modest settings.
  • Target SpO2 typically 92–96% (or 88–92% in COPD/CO2 retainers as appropriate).
• Ventilation adequate: pH acceptable (often ≥ 7.30) with manageable PaCO2 for that patient.
• Haemodynamic stability: minimal/no vasopressors, no uncontrolled arrhythmia/ischaemia.
• Neurological: awake enough to initiate breaths and protect airway; delirium/agitation controlled.
• Temperature, Hb, electrolytes: treat fever, anaemia, hypophosphataemia, hypomagnesaemia, hypokalaemia which impair muscle function.
• Airway/secretions: manageable secretions, effective cough, suctioning not excessively frequent.

Weaning strategies (ICU)

• Daily protocolised approach: SAT + SBT reduces duration of ventilation and ICU stay.
• SBT methods: T-piece, CPAP, or low-level pressure support (e.g., PS 5–8 cmH2O with PEEP 5).
  • Duration often 30–120 minutes depending on unit protocol and patient risk.
• Gradual reduction: reduce PS, reduce SIMV rate (less favoured), or switch to assisted modes; avoid prolonged SIMV-only weans if not progressing.
• Adjuncts: physiotherapy, early mobilisation, optimise nutrition, treat fluid overload, bronchodilators, diuresis if weaning-induced pulmonary oedema suspected.
• Tracheostomy: consider if prolonged ventilation anticipated, difficult wean, heavy secretion burden, or need for ongoing airway protection; balance against procedural risk.

Predictors/indices (useful but not definitive)

• RSBI (rapid shallow breathing index) = f/VT (breaths/min divided by litres).
  • RSBI < 105 often associated with weaning success, but performance varies; interpret in context.
• Respiratory muscle strength: NIF/MIP more negative than about −20 to −30 cmH2O suggests adequate strength (context-dependent).
• Vital capacity (older metric): >10–15 mL/kg sometimes quoted; limited ICU utility.
• Cuff leak test: assesses risk of post-extubation laryngeal oedema/stridor (not a test of readiness to breathe).

Extubation readiness: a structured approach

• 1) Can they breathe? (ventilation/oxygenation likely to be sustained off the ventilator)
  • Successful SBT without distress: stable RR, acceptable gas exchange, no marked tachycardia/HTN, no diaphoresis or agitation.
• 2) Can they protect their airway? (conscious level, cough, swallow, secretion burden)
  • Assess: cough on suction/catheter, ability to manage secretions, gag not required.
• 3) Is the upper airway patent? (laryngeal oedema, obstruction risk)
  • Risk factors for oedema: prolonged intubation, traumatic intubation, large tube, female, high cuff pressures, airway surgery, prone positioning, fluid overload.
  • If high risk: cuff leak test, consider steroids (e.g., dexamethasone) pre-extubation per local policy; plan for stridor management.
• 4) Is there a plan if it fails? (re-intubation strategy, equipment, skilled help, ceiling of care)

High-risk extubation (ICU and theatre): identification and planning

• High-risk features:
  • Difficult re-intubation predicted/known (airway pathology, limited mouth opening/neck movement, obesity, previous difficult intubation).
  • High risk of obstruction: airway oedema, head/neck surgery, airway burns, OSA, haematoma risk.
  • High risk of respiratory failure: COPD, heart failure, neuromuscular weakness, high secretion load, poor cough, borderline gas exchange, prolonged ventilation.
• Planning options:
  • Extubate fully awake where appropriate; ensure full reversal of neuromuscular blockade (quantitative TOF).
  • Staged extubation with airway exchange catheter (AEC) left in situ for rapid re-intubation; oxygen insufflation via AEC only with caution and appropriate technique due to barotrauma risk.
  • Extubate to HFNO or NIV (particularly COPD, obesity hypoventilation, cardiogenic pulmonary oedema, post-op high-risk).
  • Delay extubation / consider tracheostomy if airway patency or protection is doubtful.

Practical extubation sequence (ICU/theatre)

• Preparation: suction oral + ETT, sit up, pre-oxygenate, ensure monitoring, check cuff pressure history, confirm plan and re-intubation kit readiness.
• Optimise: analgesia, antiemetic, bronchodilator if wheezy, treat fluid overload, ensure normothermia.
• Reversal: ensure no residual paralysis (quantitative TOF ratio ≥ 0.9).
• Extubation: deflate cuff, remove at end-inspiration (common practice), apply oxygen, encourage cough, clear secretions.
• Post-extubation: continuous observation, early ABG if concern, chest physio, humidification, consider HFNO/NIV, manage pain and delirium.

Post-extubation complications and management

• Upper airway obstruction/stridor (laryngeal oedema):
  • Immediate: high-flow oxygen, sit up, nebulised adrenaline, IV dexamethasone (if not already), consider heliox where available, call for help early.
  • If worsening/impending obstruction: early re-intubation (do not persist with temporising measures).
• Laryngospasm (more theatre than ICU): jaw thrust, CPAP with 100% O2, deepen anaesthesia, consider small-dose propofol; if persistent, suxamethonium and intubate/ventilate.
• Respiratory failure (hypoxaemia/hypercapnia): treat cause (atelectasis, bronchospasm, pulmonary oedema, pneumonia, PE, opioid excess). Use HFNO/NIV when appropriate; re-intubate early if failing.
• Aspiration: suction, oxygen, consider bronchoscopy if particulate, antibiotics only if infection suspected (not routine), re-intubate if needed.
• Negative pressure pulmonary oedema (post-obstruction): oxygen, CPAP/PEEP, diuretics if appropriate, consider re-intubation/ventilation.
• Haemodynamic instability/ischaemia during wean/extubation: treat pain/anxiety, optimise preload/afterload, consider echo, diuresis/vasodilators/inotropes as indicated.

Extubation in selected groups (high-yield)

• COPD/CO2 retainers:
  • Accept permissive hypercapnia if pH acceptable; extubate to NIV if high risk; avoid excessive oxygen (target saturations per patient).
• Obesity/OSA:
  • Head-up positioning, extubate fully awake, consider CPAP/NIV, aggressive atelectasis prevention (PEEP, recruitment, early mobilisation).
• Neuromuscular disease/weakness:
  • High risk of failure due to weak cough/secretions; consider NIV, cough assist, and lower threshold for tracheostomy if prolonged.
• Head/neck surgery or airway oedema risk:
  • Consider delayed extubation, cuff leak assessment, steroids, AEC/staged extubation; ensure immediate access to re-intubation and surgical airway expertise.