In an adult mechanically ventilated patient who is ready for extubation (adequate mental status, stable hemodynamics, minimal secretions, acceptable oxygenation), how is a cuff‑leak test performed, what leak volume or percentage defines an adequate leak, and what should be done if the leak is absent or minimal?

Cuff-Leak Test: Performance and Management

How to Perform the Test

The cuff-leak test should be performed by positioning the patient semi-recumbent, thoroughly suctioning oral and tracheal secretions, setting the ventilator to assist-control volume mode, ensuring adequate sedation to prevent coughing, then deflating the endotracheal tube cuff and measuring the difference between the inspired tidal volume (with cuff inflated) and the average of the three lowest expired tidal volumes among six measurements after cuff deflation. 1

Step-by-Step Technique:

• Patient preparation: Semi-recumbent positioning with thorough suctioning to remove secretions 1
• Ventilator settings: Assist-control mode (volume control) 1
• Sedation: Ensure adequate sedation as coughing significantly reduces measurement reliability 1
• Measurement: Calculate absolute leak volume as inspired Vt (cuff inflated) minus average expired Vt (cuff deflated) 1
• Alternative calculation: Relative leak volume = (absolute leak volume ÷ inspired Vt) × 100% 1

Defining an Adequate Leak

A cuff leak volume of ≥110 mL (absolute) or ≥10% (relative) indicates an adequate leak and low risk for post-extubation complications. 1, 2

Interpretation Thresholds:

• Positive test (high risk): Absolute leak volume <110 mL or relative leak volume <10% 1
• Negative test (low risk): Absolute leak volume ≥110 mL or relative leak volume ≥10% 1, 2

Test Performance Characteristics:

• Specificity: Excellent at 87-92%, meaning a positive test reliably identifies high-risk patients 3, 1
• Sensitivity: Only moderate at 56-66%, meaning the test misses many patients who will develop complications 3, 1
• Negative predictive value: 97-98%, making it highly reliable for indicating low risk 3, 1
• Positive predictive value: Only 12-15%, meaning most patients who fail the test will NOT develop postextubation stridor 3, 4

Management When Leak is Absent or Minimal

If the cuff-leak test is positive (absent or minimal leak), administer systemic corticosteroids (prednisolone 1 mg/kg/day or equivalent) at least 4-6 hours before extubation, then proceed with extubation 4-12 hours after steroid administration rather than delaying extubation indefinitely. 3, 1, 4

Management Algorithm for Failed Cuff-Leak Test:

Immediate intervention:

• Give systemic corticosteroids immediately upon positive test 3, 4
• Prednisolone 1 mg/kg/day (or equivalent dose of alternative corticosteroid) 3, 4
• Oral and parenteral (IV) steroids have similar efficacy; oral route is preferred due to fewer administration-related complications 4

Timing of extubation:

• Administer steroids at least 4 hours before extubation 5, 3, 4
• Proceed with extubation 4-12 hours after steroid administration 3, 1, 4
• Do NOT delay extubation for days, as ongoing mechanical ventilation carries its own risks 5, 4

Evidence for steroid efficacy:

• Systemic steroids reduce reintubation rate from 17.0% to 5.8% (RR 0.32; 95% CI 0.14-0.76) 5, 3
• Systemic steroids reduce postextubation stridor rate from 31.9% to 10.8% (RR 0.35; 95% CI 0.20-0.63) 5, 3

Post-Extubation Monitoring:

• Postextubation stridor typically occurs within minutes of extubation 4
• Have equipment ready for high-flow nasal cannula oxygen therapy 4
• Prepare nebulized racemic epinephrine for stridor treatment 4
• Be prepared for reintubation if severe airway obstruction develops 4

Who Should Undergo Testing

The cuff-leak test should be reserved for high-risk patients, including those with intubation duration >6 days, traumatic or difficult intubation, large endotracheal tube size, female sex, and reintubation after unplanned extubation. 3, 4

The American Thoracic Society/American College of Chest Physicians recommend performing the test several hours before planned extubation in these high-risk patients 3

Important Caveats and Pitfalls

Despite a negative cuff-leak test, patients still require close post-extubation monitoring due to the test's moderate sensitivity (only 56-66%). 3, 1

Technical Limitations:

• The test is susceptible to tube size, respiratory system compliance and resistance, and airway collapse 3
• Coughing during cuff deflation hinders accurate measurement and lowers reproducibility 3, 1
• Inspiratory flow and system compliance significantly affect the test through effects on the inspiratory component of the total leak 6

Clinical Context:

• The test should not be relied upon as the sole predictor of post-extubation airway complications 3
• The low positive predictive value (12-15%) means that most patients who fail the test will NOT develop postextubation stridor, but the intervention (steroids) is still warranted given the high specificity and potential severity of complications 3, 4
• Laryngeal edema is more common among patients intubated >36 hours, with an incidence of postextubation stridor of 6-37% 5