What is a daily protocol for weaning an adult intensive care unit (ICU) patient from mechanical ventilation, including readiness criteria (improving underlying problem, adequate partial pressure of arterial oxygen (PaO2) >55 mmHg on fraction of inspired oxygen (FiO2) ≤0.40, PaO2/FiO2 ≥200, stable hemodynamics without vasopressors, light sedation, positive end‑expiratory pressure (PEEP) ≤5 cm H2O, pressure support ≤8 cm H2O, and rapid shallow breathing index (RSBI) ≤105 breaths/min/L), spontaneous breathing trial (SBT) settings and stop criteria, post‑extubation oxygen targets and prophylactic non‑invasive ventilation (NIV) or high‑flow nasal cannula (HFNC) for high‑risk patients, definition of extubation success, and management of difficult or prolonged weaning?

Protocol for Liberation from Mechanical Ventilation

Daily Readiness Assessment

Implement a standardized daily screening protocol performed by respiratory therapists or nurses to identify patients ready for weaning, with physician approval required only for the final extubation decision. 1

Assess all of the following criteria each morning:

• Resolution or significant improvement of the primary condition requiring mechanical ventilation 1
• Adequate oxygenation: PaO₂ >55 mmHg on FiO₂ ≤0.40, with PaO₂/FiO₂ ≥200 1
• Low ventilatory requirements: PEEP ≤5 cm H₂O, pressure support ≤8 cm H₂O 1
• Hemodynamic stability: No active myocardial ischemia, no vasopressor requirements, mean arterial pressure >65 mmHg 1, 2
• Adequate mental status: Patient arousable with light or no sedation 1
• Respiratory mechanics: RSBI ≤105 breaths/min/L (ideally <80) measured after 30-60 minutes of spontaneous breathing 1
• Airway protection: Intact cough on suctioning with minimal secretions or effective clearance mechanism 1

Spontaneous Breathing Trial (SBT) Protocol

Standard-Risk Patients

Conduct the initial SBT using pressure support ventilation of 5-8 cm H₂O with PEEP 5 cm H₂O rather than T-piece, as this approach increases SBT success rates from 76.7% to 84.6% and extubation success from 68.9% to 75.4%. 3, 1

SBT settings:

• Pressure support: 5-8 cm H₂O 3, 1
• PEEP: 5 cm H₂O 1
• FiO₂: ≤0.40 1
• Duration: 30 minutes 1, 4

High-Risk Patients

For patients at high risk of extubation failure, conduct a longer SBT of 60-120 minutes and consider using T-piece or CPAP without pressure support for more accurate assessment of true extubation readiness. 1, 4

High-risk criteria include:

• Age >65 years 3
• Cardiac failure as cause of respiratory failure 3
• APACHE II score >12 on day of extubation 3
• Failed more than one SBT 3
• PaCO₂ >45 mmHg after extubation 3
• More than one comorbid condition (COPD, CHF) 3
• Weak cough or excessive secretions 3
• Prolonged mechanical ventilation (>14 days) 4

SBT Failure Criteria - Stop Immediately If:

• Respiratory rate >35 breaths/min or increasing trend 1
• SpO₂ <90% 1
• Heart rate >140 bpm or sustained increase >20% 1
• Systolic blood pressure >180 mmHg or <90 mmHg 1
• Increased anxiety or diaphoresis 1
• Use of accessory muscles or abdominal paradox 1

If the SBT fails, return the patient to full ventilatory support for at least 24 hours before attempting another trial; do not repeat SBTs on the same day as this can cause respiratory muscle fatigue and worsen outcomes. 4

Post-Extubation Management

Standard-Risk Patients

Extubate directly to supplemental oxygen via face mask or nasal cannula, targeting SpO₂ 88-92%. 1

• Monitor SpO₂, respiratory rate, and work of breathing continuously for the first 24 hours 1
• Use supplemental oxygen cautiously, particularly in patients with chronic hypercapnia, to avoid masking hypoventilation or atelectasis 1

High-Risk Patients - Prophylactic NIV or HFNC

For high-risk patients who pass the SBT, apply prophylactic noninvasive ventilation (NIV) immediately after extubation (within 1 hour) rather than waiting for respiratory failure, as this reduces reintubation rates (RR 1.14,95% CI 1.05-1.23), ICU mortality (RR 0.37,95% CI 0.19-0.70), and ICU length of stay by 2.48 days. 3

NIV settings:

• IPAP: 10-12 cm H₂O 1
• EPAP: 5-10 cm H₂O 1
• FiO₂: Titrate to maintain SpO₂ 88-92% 1

Alternative: High-flow nasal cannula (HFNC) reduces reintubation rates compared to conventional oxygen therapy (4% vs 21%, P=0.01) and may be used in low-risk patients or when NIV is not tolerated 3

Patients with hypercapnia (PaCO₂ >45 mmHg) during the SBT derive particular benefit from prophylactic NIV, with reduced 90-day mortality (RR 0.58,95% CI 0.27-1.22). 3

Definition of Extubation Success

Extubation is considered successful if the patient does not require reintubation or noninvasive ventilation within 48 hours. 4

• The acceptable extubation failure rate should be 5-10%; higher rates suggest inadequate assessment 4
• Approximately 10% of patients who pass an SBT will still fail extubation within 48 hours 1, 4

Management of Difficult or Prolonged Weaning

Classification

• Simple weaning: Successfully pass first SBT and extubate on first attempt (70% of patients) 1
• Difficult weaning: Require up to 3 SBTs or up to 7 days from first SBT (15% of patients) 1
• Prolonged weaning: Require >3 SBTs or >7 days after first SBT (15% of patients) 1

Approach to Difficult/Prolonged Weaning

For patients who fail multiple SBTs, switch from T-piece trials to gradual reduction of pressure support ventilation (reduce by 2 cm H₂O every 24-48 hours) rather than repeating daily T-piece trials, as this reduces inspiratory muscle effort and cardiovascular stress. 2

Identify and address reversible causes:

• Respiratory muscle weakness: Perform diaphragmatic ultrasound to evaluate diaphragm thickness and excursion 2
• Fluid overload: Consider forced diuresis if pulmonary edema is evident; fluid overload can exceed 20 liters in difficult-to-wean patients 2
• Metabolic alkalosis: Bicarbonate >30 mmol/L diminishes respiratory drive; correct by reducing diuretics and repleting chloride with normal saline 2
• Inadequate oxygenation: Increase PEEP to 8-10 cm H₂O while targeting PaO₂/FiO₂ >200 mmHg; keep driving pressure <15 cm H₂O 2
• Excessive sedation: Reduce sedation to encourage spontaneous breathing efforts 2

For patients with hypercapnic respiratory failure (especially COPD), consider early transition to NIV to facilitate weaning, which reduces mortality (RR 0.54,95% CI 0.41-0.70), weaning failure (RR 0.61,95% CI 0.48-0.79), and ventilator-associated pneumonia (RR 0.22,95% CI 0.15-0.32). 1

Critical Pitfalls to Avoid

• Do not commence weaning when PaO₂ <55 mmHg on FiO₂ ≥0.40, as weaning failure probability is markedly increased 1
• Do not use SIMV for weaning, as it is inferior to pressure support and T-piece methods 1
• Do not rely solely on SBT success to predict extubation readiness; also assess upper airway patency, bulbar function, sputum load, and cough effectiveness 1, 4
• Do not delay extubation in patients who pass their first SBT, are <65 years old, have normal PaCO₂, and have no significant respiratory or cardiac comorbidities, as these low-risk patients rarely require prophylactic NIV 3
• Avoid premature weaning in patients still requiring vasopressors or with unresolved primary pathology 1