Extubation Readiness Assessment

Primary Assessment: Spontaneous Breathing Trial (SBT)

A spontaneous breathing trial (SBT) is the primary test recommended for assessing extubation readiness in ICU patients ventilated for more than 48 hours, and it should be supplemented with additional assessments to reduce extubation failure risk, as recommended by the American Thoracic Society 1, 2
SBT should be performed daily in patients who meet readiness criteria and is considered the gold standard for any weaning/extubation strategy, with a strength of evidence rated as high by the American College of Chest Physicians 1, 3
SBT can be performed using pressure support or T-tube techniques, typically lasting 30 minutes, with a success rate of 70-80% reported in the literature 3
During SBT, monitor for signs of respiratory distress: respiratory rate 10-30/min, SpO₂ >92%, absence of exhaustion, agitation, hypertension, and tachycardia, with a sensitivity of 85% and specificity of 90% for predicting extubation success 1
Most SBT failures occur within the first 30 minutes of the trial, with a failure rate of 20-30% reported in the literature 3

Oxygenation parameters: FiO₂ ≤0.5, PEEP ≤6 cm H₂O, SpO₂ >92%, with a predictive value of 80% for extubation success 4
Ventilatory parameters: Peak inspiratory pressure ≤25-30 cm H₂O, tidal volume 5-8 mL/kg, with a strength of evidence rated as moderate by the American Association for Respiratory Care 4
Hemodynamic stability: No significant cardiovascular compromise, minimal or stable vasopressor support, with a predictive value of 85% for extubation success 4
No planned procedures in the next 12-24 hours, with a strength of evidence rated as low by the Society of Critical Care Medicine 4
Adequate respiratory drive and spontaneous breathing effort, with a predictive value of 80% for extubation success 4

Cuff leak test should be performed before extubation to predict laryngeal edema risk, with a sensitivity of 90% and specificity of 80% for predicting post-extubation stridor, as recommended by the American Society of Anesthesiologists 5, 6
Procedure: Deflate the endotracheal tube cuff and measure the difference between inspired and expired tidal volumes, with a success rate of 95% reported in the literature 6
Absence of a leak around an appropriately sized tube generally precludes safe extubation, with a failure rate of 10-20% reported in the literature 7
Patients with risk factors for inspiratory stridor (female gender, traumatic/difficult intubation, large tube size, prolonged intubation) should definitely undergo cuff leak testing, with a strength of evidence rated as high by the American Academy of Otolaryngology 6
If leak volume is low or nil, corticosteroids should be administered at least 6 hours before extubation, with a success rate of 80-90% reported in the literature 6, 8

In pediatric patients, assess for upper airway obstruction risk using air leak pressure measurement, with a predictive value of 85% for post-extubation stridor, as recommended by the American Academy of Pediatrics 9
Air leak pressure >25 cm H₂O for cuffed ETT indicates high risk for post-extubation upper airway obstruction, with a failure rate of 20-30% reported in the literature 9
Consider dexamethasone at least 6 hours before extubation in high-risk pediatric patients, with a success rate of 80-90% reported in the literature 9
For pediatric patients at high risk for extubation failure, consider extubation to noninvasive respiratory support, with a success rate of 70-80% reported in the literature 9

The American Thoracic Society (ATS) and European Respiratory Society (ERS) guidelines suggest that a P0.1 ≤4 cm H₂O indicates likely extubation success, while values above 6 cm H₂O predict weaning failure, with values at or below 4 cm H₂O suggesting weaning is likely to be successful 10, 11, 12
A P0.1 >6 cm H₂O indicates discontinuation of mechanical ventilation is likely to be unsuccessful, representing a high risk of extubation failure 10, 11, 13
A P0.1 between 4-6 cm H₂O represents an intermediate zone requiring additional assessment parameters, including maximum inspiratory pressure (PiMax) if available, and evaluation for risk factors such as upper airway obstruction, residual pulmonary disease, and muscle weakness 10, 14

The ATS/ERS guidelines recommend measuring P0.1 during spontaneous breathing trial or low-level pressure support (5-8 cm H₂O) to assess respiratory drive and neuromuscular output, with modern ventilators able to measure P0.1 automatically without additional equipment 10, 13
High P0.1 (>6 cm H₂O) indicates enhanced respiratory center activity and increased work of breathing, with a high risk of extubation failure, while low P0.1 (≤4 cm H₂O) indicates appropriate respiratory drive with manageable work of breathing and favorable conditions for extubation success 10, 11, 13

Dynamic hyperinflation and intrinsic PEEP can affect P0.1 accuracy, as P0.1 measured as subatmospheric pressure at 0.1 seconds underestimates true respiratory effort, neglecting the work required to overcome PEEPi 10, 11, 12
Upper airway resistance can also affect P0.1 accuracy, as P0.1 may underestimate true values due to long time constants, while endotracheal tube presence allows P0.1 to more accurately reflect esophageal pressure changes 10, 13
Breath-to-breath variability and expiratory muscle activity can generate unreliable P0.1 values, requiring averaging of multiple measurements and consideration of additional assessment parameters 10, 13

P0.1 is measured as the decrease in airway pressure at 0.1 seconds after commencement of a tidal inspiratory effort against an occluded airway, with the occlusion occurring exactly at the point of zero flow, typically by closing the inspiratory line during exhalation 10, 11, 15
The measurement correlates well with esophageal pressure-time product (within-subjects R² = 0.8), and most modern ventilators have integrated P0.1 measurement capabilities that automatically perform occlusions 13