What should the Positive End-Expiratory Pressure (PEEP) be set at for a successful Spontaneous Breathing Trial (SBT)?

PEEP Settings for Spontaneous Breathing Trials

For a successful spontaneous breathing trial (SBT), PEEP should be set at 5 cm H₂O with pressure support of 5-8 cm H₂O, rather than using zero PEEP or T-piece alone. 1

Guideline-Based Recommendations

The American College of Chest Physicians/American Thoracic Society 2017 guidelines provide a conditional recommendation (moderate-quality evidence) that initial SBTs should be conducted with inspiratory pressure augmentation of 5-8 cm H₂O rather than T-piece or CPAP alone. 1 This approach:

• Increases SBT success rates to 84.6% versus 76.7% with T-piece 1, 2
• Improves extubation success to 75.4% versus 68.9% with T-piece 1, 2
• Shows a trend toward lower ICU mortality (8.6% vs 11.6%) 3

Specific PEEP Parameters by Clinical Context

Standard-Risk Patients

• Use PEEP of 5 cm H₂O with pressure support 5-8 cm H₂O 1, 2
• Duration: 30 minutes is sufficient for most patients 3, 2
• This combination reduces work of breathing while still adequately assessing extubation readiness 4

High-Risk Patients

• Consider CPAP without pressure support augmentation (PEEP alone) for more stringent assessment 3
• Duration: 60-120 minutes recommended 3, 2
• High-risk features include: prolonged ventilation >14 days, chronic lung disease, myocardial dysfunction, neurologic impairment, or previous extubation failure 3, 5

Alternative Approach for Difficult-to-Wean Patients

• Initial trial: Zero PEEP/zero pressure support (ZEEP) 6
• If ZEEP fails: Immediately perform 5/5 trial (5 cm H₂O PEEP + 5 cm H₂O pressure support) 6
• This algorithmic approach achieved 96.2% successful liberation (82.4% with ZEEP alone, plus 13.8% who passed subsequent 5/5 trial) 6

Physiological Rationale

PEEP during SBT provides critical physiological support that more accurately reflects post-extubation conditions:

• Reduces inspiratory muscle effort significantly - esophageal pressure-time product was 128-148 cmH₂O·s/min with pressure support versus 292 cmH₂O·s/min with T-piece 4
• Prevents left ventricular failure - 11 of 14 difficult-to-wean patients developed LV failure during T-piece but not during pressure-supported trials 4
• Maintains lower pulmonary artery occlusion pressure - 17 mmHg with PSV-PEEP versus 21 mmHg with T-piece 4
• Improves breathing pattern - respiratory rate 19 breaths/min with PSV-PEEP versus 27 breaths/min with T-piece 4

Common Pitfalls to Avoid

Do not use T-piece alone as the initial SBT method - this may be overly stringent and delay extubation in patients who could successfully extubate, as T-piece trials underestimate the support provided by maintaining airway patency after extubation 1, 3

Do not assume pressure-supported SBTs guarantee extubation success - approximately 10% of patients who pass an SBT still fail extubation within 48 hours, requiring assessment of upper airway patency, bulbar function, sputum load, and cough effectiveness 3, 5

Avoid same-day repeat SBTs after failure - failed SBTs indicate respiratory muscle fatigue requiring time to resolve before another attempt 3

Post-Extubation Considerations

For high-risk patients who pass the SBT, use prophylactic noninvasive ventilation immediately after extubation rather than standard oxygen therapy (strong recommendation, moderate-quality evidence) 1, 5, 2