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Wening criteria

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"ventilator weaning"[MeSH Terms] AND "spontaneous breathing trial"

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I read "Wening criteria" as weaning criteria, meaning the criteria for weaning a patient off mechanical ventilation. If you meant something else, such as weaning from ECMO or parenteral nutrition, tell me.

Weaning criteria (liberation from mechanical ventilation)

Weaning is a two-step process. First you screen for readiness, then you run a spontaneous breathing trial (SBT). Assess readiness daily once the underlying disease starts to resolve.

1. Readiness to wean (screening)

These criteria are from the Washington Manual of Medical Therapeutics (section "Liberation From Mechanical Ventilation"):
  • Minimal ventilator support: FiO2 ≤40% and PEEP ≤5 cm H2O, keeping SpO2 >90%.
  • ABG: pH and PaCO2 at the patient's baseline. This matters most in chronic CO2 retainers.
  • Ventilation requirement: minute ventilation <10 L/min and respiratory rate <30/min.
  • Mental status: awake, alert and cooperative.
  • Secretions: thin, scant and easily suctioned, needing suction no more often than every 4 hours.
  • Strength: strong cough, and able to lift the head off the bed and hold it for >5 seconds.
  • Spontaneous tidal volume: >5 mL/kg ideal body weight.
  • Rapid shallow breathing index (RSBI, Tobin index): RR divided by VT in litres should be ≤105. An RSBI >105 predicts failure accurately. An RSBI ≤105 is less accurate at predicting success.
  • Airway patency: check for a cuff leak if laryngeal edema is a concern. If there is no leak, usually delay extubation and give IV steroids for 12-24 hours first.
Most clinical protocols also expect the following, which are not all in the sources I pulled:
  • The cause of respiratory failure is improving.
  • The patient is hemodynamically stable, with no or minimal vasopressors.
  • There is no active myocardial ischemia.
  • Sedation is interrupted.

2. Spontaneous breathing trial

  • Do a daily SBT of 30-120 minutes. Combined with daily sedation interruption, this is the strongest predictor of timely liberation.
  • Methods:
    • T-piece: the patient is off the ventilator but still intubated.
    • Low-level pressure support: PS 5-10 cm H2O with PEEP about 5.
  • SIMV has the poorest weaning outcomes.
  • A 30-minute trial is as effective as a 2-hour trial in patients not expected to have difficulty.
  • A single daily trial is as effective as several trials a day, and simpler.
  • If the SBT fails, give at least 24 hours of full ventilator rest before the next attempt (Fishman's Pulmonary Diseases and Disorders, "Weaning Trials").

3. SBT failure signs (stop the trial)

These come from standard teaching, not the sources I pulled:
  • RR >35/min
  • SpO2 <90%
  • HR >140/min or a sustained change of more than 20%
  • Systolic BP >180 or <90 mmHg
  • Agitation, diaphoresis or anxiety
  • Rapid shallow breathing

4. After extubation

  • Failure rates as high as 23.5% have been reported even when all objective criteria are met.
  • COPD or chronic hypercapnic failure: extubation to NPPV lowers mortality, pneumonia and reintubation.
  • Select low-risk patients: high-flow nasal cannula reduces reintubation within 48-72 hours, and is noninferior to NPPV.
Sources: Washington Manual of Medical Therapeutics, Liberation From Mechanical Ventilation, p. 292. Fishman's Pulmonary Diseases and Disorders, Weaning Trials.

Recent evidence check

A PubMed search of the last 2 years found nothing that contradicts the above. Recent systematic reviews cover:
  • Left ventricular systolic dysfunction and weaning failure (PMID 40544079)
  • Paired spontaneous awakening and breathing trials (PMID 40423382)
  • Nurse-led weaning protocols (PMID 40823569)
If you want a specific angle, I can go deeper on one of these: RSBI and other predictors, difficult or prolonged weaning, tracheostomy weaning, or extubation failure risk.
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