How to assess patient readiness for a Spontaneous Breathing Trial (SBT)?

Assessing Patient Readiness for Spontaneous Breathing Trial

Use daily protocolized screening with an extubation readiness testing (ERT) bundle to assess SBT eligibility, rather than relying on clinical judgment alone. 1

Daily Screening Criteria

Perform daily assessment of the following readiness criteria before initiating an SBT:

• Clinical stability: Resolution or improvement of the primary cause of respiratory failure 1, 2
• Adequate oxygenation: Patient can maintain acceptable oxygen saturation on current support 1, 2
• Hemodynamic stability: No active myocardial ischemia, no significant vasopressor requirements 1, 2
• Ventilator mode transition: Switch from controlled to assisted ventilation as soon as patient recovery allows 1, 2
• Sedation level: Patient should be awake and cooperative, with Richmond Agitation Scale Score (RASS) ideally at 0 (alert and calm) 2, 3

Protocolized Extubation Readiness Testing (ERT) Bundle

Implement a comprehensive ERT bundle that includes the SBT plus additional objective assessments, which reduces extubation failure rates by 3.3-11.7% with 90% sensitivity and 94% positive predictive value for extubation success. 1, 2

The ERT bundle must assess:

• Respiratory muscle strength: Use maximal inspiratory pressure (PiMax) measurement, particularly for patients at risk for muscle weakness or extubation failure 1
• Upper airway patency: Perform endotracheal tube air leak test in patients with cuffed tubes to assess risk of postextubation upper airway obstruction 1
• Neurologic control: Evaluate bulbar function and ability to protect the airway 1, 2
• Secretion management: Assess sputum load and cough effectiveness 1, 2
• Gas exchange capability: Confirm patient can maintain adequate minute ventilation without excessive respiratory effort 1

Risk Stratification for SBT Method Selection

Standard-Risk Patients

Use either pressure support (5-8 cm H₂O) with CPAP or CPAP alone during the SBT. 1, 4

Standard-risk patients include those without:

• Prolonged mechanical ventilation (>14 days) 2, 5
• Chronic lung disease 2, 5
• Myocardial dysfunction 2, 5
• Neurologic impairment or neuromuscular disease 2, 5
• Previous failed extubation 2, 5

High-Risk Patients

Use CPAP without pressure support augmentation (or T-piece) for more accurate assessment of true extubation readiness. 1, 2

High-risk criteria include:

• Previously failed extubation attempts 2, 5
• Upper airway anomalies 2, 5
• Ineffective cough or impaired bulbar function 2, 5
• Borderline passing of previous SBT 2

SBT Duration Protocol

• Standard-risk patients: Conduct SBT for 30 minutes, as most failures occur within this timeframe 1, 2, 4
• High-risk patients: Extend SBT duration to 60-120 minutes for better predictive accuracy 1, 2

Critical Pitfalls to Avoid

Do not rely solely on SBT success to predict extubation readiness—approximately 10% of patients who pass an SBT will still fail extubation within 48 hours. 1, 2, 5

Do not perform repeat SBTs on the same day after failure, as this can lead to respiratory muscle fatigue and worsening respiratory mechanics. 2 Instead, identify and address the underlying causes of failure before attempting another trial the following day. 2

Do not use Synchronized Intermittent Mandatory Ventilation (SIMV) for weaning, as it is inferior to pressure support and T-piece methods. 1

Do not ignore non-respiratory factors that affect extubation success, including upper airway patency, bulbar function, sputum load, and cough effectiveness—these must be systematically evaluated even after a successful SBT. 1, 2, 5

Documentation Requirements

Create a documented weaning plan that includes:

• Specific readiness criteria met 1, 2
• SBT method and duration used 2, 3
• Physiological parameters during the trial 2, 3
• Clinical extubation criteria assessed 2, 3
• Plan for post-extubation respiratory support, particularly for high-risk patients 2, 5