What is the target airway occlusion pressure (P0.1) for extubation?

Airway Occlusion Pressure (P0.1) Goals for Extubation

For successful extubation, target a P0.1 ≤4 cm H₂O, as values above 6 cm H₂O predict weaning failure, while values at or below 4 cm H₂O indicate likely extubation success. 1

Evidence-Based P0.1 Thresholds

The ATS/ERS guidelines establish clear cutoff values for P0.1 in predicting extubation outcomes:

• P0.1 ≤4 cm H₂O: Suggests weaning is likely to be successful 1
• P0.1 >6 cm H₂O: Indicates discontinuation of mechanical ventilation is likely to be unsuccessful 1
• P0.1 between 4-6 cm H₂O: Represents an intermediate zone requiring additional assessment parameters 1

Clinical Application Algorithm

Step 1: Measure P0.1 During Pre-Extubation Assessment

• Measure P0.1 during spontaneous breathing trial or low-level pressure support (5-8 cm H₂O) 1
• The measurement reflects respiratory drive and neuromuscular output, not just inspiratory center activity 1
• Modern ventilators can measure P0.1 automatically without additional equipment 1, 2

Step 2: Interpret P0.1 in Context

High P0.1 (>6 cm H₂O) indicates:

• Enhanced respiratory center activity and increased work of breathing 1
• High risk of extubation failure - delay extubation and address underlying causes 1
• May reflect increased respiratory load, muscle weakness, or inadequate ventilatory support 1

Low P0.1 (≤4 cm H₂O) indicates:

• Appropriate respiratory drive with manageable work of breathing 1
• Favorable conditions for extubation success 1
• Proceed with extubation if other readiness criteria are met 3

Intermediate P0.1 (4-6 cm H₂O) requires:

• Additional assessment with maximum inspiratory pressure (PiMax) if available 1
• Evaluation for risk factors: upper airway obstruction, residual pulmonary disease, muscle weakness 1
• Consider prophylactic noninvasive ventilation after extubation 4

Step 3: Post-Extubation Monitoring

• Measure P0.1 at 1 hour post-extubation to detect early respiratory distress 5
• P0.1 >4.2 cm H₂O at 1 hour post-extubation predicts respiratory failure requiring reintubation 5
• P0.1 ≤1.8 cm H₂O at 1 hour post-extubation indicates stable respiratory status 5

Critical Caveats and Limitations

Factors That Affect P0.1 Accuracy

• Dynamic hyperinflation and intrinsic PEEP: P0.1 measured as subatmospheric pressure at 0.1 seconds underestimates true respiratory effort, as it neglects the work required to overcome PEEPi 1
• Upper airway resistance: In patients with abnormal airway resistance breathing through intact upper airways, P0.1 may underestimate true values due to long time constants 1
• Endotracheal tube presence: In intubated patients, the rigid ETT bypassing the compliant upper airway allows P0.1 to more accurately reflect esophageal pressure changes 1
• Breath-to-breath variability: P0.1 shows significant variability between breaths, requiring averaging of multiple measurements 1, 2
• Expiratory muscle activity: Active expiration increases P0.1 variability and generates unreliable values 1

When P0.1 Alone Is Insufficient

P0.1 should not be used in isolation for extubation decisions. A low P0.1 may reflect:

• Reduced respiratory center output 1
• Deterioration in neural pathways to respiratory muscles 1
• Impaired electromechanical coupling 1
• Impaired pressure-generating capacity of inspiratory muscles 1

Combine P0.1 with:

• Rapid shallow breathing index (f/VT ratio <105 breaths/min/L) 1
• Cuff leak test for airway patency 3
• Maximum inspiratory pressure (PiMax >25 cm H₂O in high-risk patients) 1
• Hemodynamic stability and adequate oxygenation (FiO₂ ≤0.5, PEEP ≤6 cm H₂O) 3

Special Populations

Pediatric Patients

• P0.1 and P0.1/P0.1max are the most useful airway pressure measurements for predicting extubation failure in children 6
• Children who fail extubation demonstrate lower P0.1 values and lower P0.1/P0.1max ratios 6
• The receiver operating characteristic curve area for P0.1 in predicting pediatric extubation failure is 0.76 6
• Combine P0.1 assessment with air leak pressure measurement (risk if >25 cm H₂O for cuffed ETT) 3

COPD Patients

• Measure P0.1 both before and 1 hour after extubation in COPD patients 5
• Post-extubation P0.1 >4.2 cm H₂O strongly predicts hypercapnic respiratory insufficiency requiring reintubation 5
• Consider prophylactic noninvasive ventilation if P0.1 is in the intermediate range (4-6 cm H₂O) 4

Measurement Technique

• 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 1
• The occlusion must occur exactly at the point of zero flow, typically by closing the inspiratory line during exhalation 1
• Patients must be unable to anticipate occlusions, which should be performed silently and unexpectedly 1
• Most modern ventilators have integrated P0.1 measurement capabilities that automatically perform occlusions 1, 2
• The measurement correlates well with esophageal pressure-time product (within-subjects R² = 0.8) 7

Performance Characteristics for Detecting Injurious Effort

• P0.1 >3.5 cm H₂O: 80% sensitive and 77% specific for detecting high inspiratory effort (≥200 cm H₂O·s·min⁻¹) 7
• P0.1 ≤1.0 cm H₂O: 100% sensitive and 92% specific for low effort (≤50 cm H₂O·s·min⁻¹) 7
• Area under ROC curve for detecting potentially high effort: 0.81 7
• Area under ROC curve for detecting potentially low effort: 0.92 7