Mechanical ventilation

Liberation: daily SAT and SBT

Reviewed Nov 2026·6 references
New· views rounded down, updated weekly

Screen every patient every morning. Pair a spontaneous awakening trial with a spontaneous breathing trial (30-120 min, pressure support 5-8 or T-piece). Extubate those who pass and can protect the airway; support high-risk patients after extubation.

At the bedside

Timed steps
  1. 1

    Readiness screen

    Every morning

    Cause improving; FiO2 ≤ 0.4-0.5 and PEEP ≤ 8 with SpO2 ≥ 90%; haemodynamically stable (no or low-dose vasopressor); some respiratory effort; able to follow commands is helpful.

  2. 2

    SAT

    Every morning

    Stop or reduce sedation (keep analgesia). Fail: agitation, RR > 35, SpO2 < 88%, arrhythmia, distress. Restart at half dose if failed.

  3. 3

    SBT

    If SAT passed

    Inspiratory pressure augmentation (PS 5-8, PEEP 0-5) rather than T-piece for the first SBT; 30 min (PS) to 120 min.

  4. 4

    Failure criteria

    During SBT

    RR > 35 for > 5 min, SpO2 < 90%, HR > 140 or ± 20%, SBP > 180 or < 90, agitation, sweating, accessory muscle use. RSBI (RR/Vt in L) > 105 suggests failure.

  5. 5

    Extubate

    Passed

    Check cough, secretions, consciousness and cuff leak (if at risk). See module 6 for extubation technique.

  6. 6

    Post-extubation support

    High risk

    Age > 65, cardiac or respiratory disease, hypercapnia, prolonged ventilation: prophylactic NIV and/or HFNC.

  7. 7

    Find why

    Failed

    Load (secretions, bronchospasm, oedema), capacity (weakness, low phosphate, sedation), cardiac (weaning-induced pulmonary oedema), neuro, anxiety. Rest on full support and retry in 24 h.

Weaning categories (ERS 2007)

CategoryDefinitionTypical mortality
SimpleExtubated after first SBT~5%
DifficultUp to 3 SBTs or ≤ 7 days from first SBTHigher
Prolonged> 3 failed SBTs or > 7 days after first SBTUp to ~25-30%
Red flag · call your senior now
Desaturation, rising BP and B-lines during SBT: weaning-induced pulmonary oedema; treat with diuretics/nitrates.
Pitfall
Not doing the SBT because the 'patient looks tired' (screen objectively).
Pitfall
Long SBTs (2 h T-piece) in patients likely to pass: 30-min PS trials are as good.
Pearl
ABC trial: pairing SAT and SBT reduced ventilator days and 1-year mortality.

Calculators for this topic

Rapid shallow breathing index

RR ÷ tidal volume in litres during a spontaneous breathing trial.

References

  1. 1

    Girard TD, Alhazzani W, Kress JP, et al. An official ATS/ACCP clinical practice guideline: liberation from mechanical ventilation in critically ill adults. Am J Respir Crit Care Med. 2017;195(1):120-133

  2. 2

    Girard TD, Kress JP, Fuchs BD, et al. Efficacy and safety of a paired sedation and ventilator weaning protocol (ABC trial). Lancet. 2008;371(9607):126-134

  3. 3

    Ely EW, Baker AM, Dunagan DP, et al. Effect on the duration of mechanical ventilation of identifying patients capable of breathing spontaneously. N Engl J Med. 1996;335(25):1864-1869

  4. 4

    Subirà C, Hernández G, Vázquez A, et al. Effect of pressure support vs T-piece ventilation strategies during spontaneous breathing trials on successful extubation. JAMA. 2019;321(22):2175-2182

  5. 5

    Boles JM, Bion J, Connors A, et al. Weaning from mechanical ventilation. Eur Respir J. 2007;29(5):1033-1056

  6. 6

    Thille AW, Muller G, Gacouin A, et al. Effect of postextubation high-flow nasal oxygen with noninvasive ventilation vs high-flow nasal oxygen alone on reintubation among patients at high risk of extubation failure (HIGH-WEAN). JAMA. 2019;322(15):1465-1475

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