Cuff Leak Test for Bilateral Vocal Cord Edema
In patients with bilateral vocal cord edema who are intubated and meet extubation criteria, perform the cuff leak test several hours before planned extubation, and if positive (leak volume <110 mL absolute or <10% relative), immediately administer systemic corticosteroids (prednisolone 1 mg/kg/day) at least 4-6 hours before proceeding with extubation rather than delaying indefinitely. 1, 2, 3
Patient Preparation and Test Technique
Before performing the test, ensure proper setup to maximize accuracy:
- Position the patient semi-recumbent and perform thorough oral and tracheal suctioning to remove secretions that could interfere with measurements 2
- Set the ventilator to assist-control mode (volume control) and ensure adequate sedation to prevent coughing, as coughing significantly reduces measurement reliability and reproducibility 2
- Measure the inspired tidal volume with the cuff inflated, then deflate the cuff and record six expired tidal volumes, calculating the average of the three lowest measurements 2
Interpreting the Results
The test yields two key measurements with specific thresholds:
- Calculate absolute leak volume as: inspired Vt (cuff inflated) minus average expired Vt (cuff deflated), with <110 mL indicating a positive test 2
- Calculate relative leak volume as: (absolute leak volume ÷ inspired Vt) × 100%, with <10% indicating a positive test 2
- Understand that the test has excellent specificity (87-92%) but only moderate sensitivity (56-66%), meaning a negative test reliably indicates low risk (negative predictive value 97-98%), but a positive test has poor positive predictive value (12-15%) 1, 2, 3
Management Algorithm Based on Test Results
If Test is Positive (Failed Cuff Leak):
- Administer systemic corticosteroids immediately—prednisolone 1 mg/kg/day or equivalent—at least 4-6 hours before extubation 1, 3
- Proceed with extubation 4-12 hours after steroid administration rather than delaying for days, as recommended by the American Thoracic Society 1, 3
- Oral and parenteral (IV) steroids have similar efficacy, with oral being preferred due to fewer administration-related complications 3
- This approach reduces reintubation rate from 17.0% to 5.8% and postextubation stridor rate from 31.9% to 10.8% 1
If Test is Negative (Passed Cuff Leak):
- Proceed with extubation as planned, but maintain standard post-extubation monitoring due to the test's moderate sensitivity (44% of complications will still be missed) 2, 3
Post-Extubation Monitoring and Rescue
Prepare for potential complications before extubation:
- Have equipment ready for high-flow nasal cannula oxygen therapy, nebulized racemic epinephrine for stridor treatment, and reintubation capability 3
- Recognize that postextubation stridor typically occurs within minutes of extubation, requiring immediate intervention 3
- Monitor closely for signs of airway obstruction, as severe laryngeal edema can progress rapidly to complete obstruction 4, 5
High-Risk Patients Requiring Testing
Reserve the cuff leak test for patients with specific risk factors, as recommended by the American College of Critical Care Medicine:
- Intubation duration >6 days 1, 3
- Traumatic or difficult intubation 1, 3
- Large endotracheal tube size 1, 3
- Female sex 1, 3
- Reintubation after unplanned extubation 1, 3
Important Caveats and Technical Limitations
Be aware of factors that affect test accuracy:
- The test is susceptible to tube size, respiratory system compliance and resistance, and airway collapse 1
- Coughing during cuff deflation significantly hinders accurate measurement and lowers reproducibility 1, 2
- Do not rely solely on the cuff leak test, as no single available test can correctly estimate the risk of post-extubation airway complications, per the American Thoracic Society 1
- Most patients who fail the test (85-86%) will NOT develop postextubation stridor, but the consequences of missing true positives are severe enough to warrant prophylactic steroid treatment 1, 3