FRCA Notes

Extubation on Critical Care

Resources

  • Extubation in critically unwell patients carries risks
    • Up to 15% of patients will require re-intubation within 48hrs
    • Post-extubation stridor occurs in 12 - 37% but no evidence for routine use of steroids

  • Protocolised weaning is advocated for extubation in many patient groups
    • A titrated work-rest cycle approach uses short bursts of high activity with prolonged periods of effective rest
    • It may be useful in patient groups where respiratory muscle fatigue is the principle cause of weaning failure e.g. COPD

Respiratory parameters

Factor Value
RR <30bpm (rapid, shallow breathing almost always due to muscular weakness)
VT >5ml/kg (or >325ml)
FVC >15ml/kg
MV <15L/min
Max Pinsp Less than -30cmH2O (normal -90 to -120cmH2O)
Rapid shallow breathing index (RR/VT; RSBI) <105bpm/L
  • Other factors include:
    • P0.1/Max Pinsp ratio >0.3
    • P0.1*RSBI <300
    • Dynamic compliance, oxygenation and Max Pinsp index
    • Integrative weaning index

General

  • Ability to protect airway post-extubation
  • Reasonable cough
  • Nutrition, anaemia and conditioning
  • General disease resolution

  • SBT's are used to identify patients who would fail liberation from mechanical ventilation
    • It is a litmus test for determining readiness to breathe without a ventilator
    • Aims to observe the patient under respiratory load conditions which simulate those following extubation
  • Recommended for any patient ventilated for >48hrs

Eligibility

  • Lung disease which is stable or resolving
  • Ventilated with:
    • An FiO2 <0.5 (P:F ratio >24kPa)
    • PEEP <5 - 10cmH2O
  • Are haemodynamically stable i.e. little-to-no vasoactive support
  • Are generating spontaneous breaths (>6bpm)

Performance

  • One's unit may have its own protocol e.g. see this one from University Hospitals Sussex
  • It seems using pressure support ventilation or a T-piece to do the SBT makes little difference to the outcome (NEJM, 2022)
  • No single parameter in isolation should be used to judge SBT success of failure
  • Having said that, of the criteria used to stop the SBT, the rapid shallow breathing index (RR/VT) is the most consistent and powerful predictor

  • Successful SBT does not guarantee successful extubation
  • Patients may still require re-intubation (approx. 20%)
  • If an SBT failed, the BREATHE trial demonstrated early extubation to NIV did not shorten time to liberation from any ventilation

  • There's some suggestion that extubating general ICU patients overnight is associated with (JAMA, 2016):
    • Shorter length of ICU stay, but not overall hospital stay
    • Greater frequency of requiring re-intubation
    • Higher ICU and in-hospital mortality
  • This may not hold true for cardiac ICU patients (Annals of Thoracic Surgery, 2019 )