Weaning From Mechanical Ventilation


Optimize Before Extubation
Withdraw sedative drugs like propofol etc. (CANNOT start SBT unless OFF sedation. Can use PRECEDEX during SBT)
Ensure adequate rest & nutrition
Prepare pt psychologically
Diurese to minimize pulmonary edema
Treat bronchospasm
Minimize secretions
Normalize electrolytes affecting muscle function (PO4, Mg, Ca)
Suppress fever with antipyretics
Treat systemic illness (infections)
Institute effective antianginal therapy
Exclude drug-induced neuromuscular blockage.
Criteria for Starting Weaning
Cause of respiratory failure improved
Adequate oxygenation: PaO2 60% on FiO2 40% (PaO2/FiO2 = 150-300) with PEEP 5
Hemodynamically stable: No myocardial ischemia or hypotension
Temp < 100.4° (38° C)
Hgb 7-10
Pt awake or easily arousable
Predicting Successful Extubation
Rapid Shallow Breathing Index (RSBI = RR ÷ Vt) < 105 during T-Piece trial best predicts successful weaning.
Higher values may be compatible with weaning in certain populations (e.g. small, elderly women) or if clinical judgment predicts success.
Conducting a Trial of Spontaneous Breathing
Give 30 min trial on T-tube or pressure support ventilation (PSV) of 5, with PEEP of 5
Consider adding CPAP (5 cm H20) for pt with obstruction (asthma, COPD)
Successful trial:
  • O2Sat > 90% or PaO2 60% mmHg on FiO2 40%
  • Increase in PaCO2 < 10 mmHg or decrease in pH < 0.10
  • RR < 35
  • RSBI < 100-105
  • HR < 140 or increased < 20% from baseline
  • sBP 80-160 or change < 20% from baseline
  • No signs of increase work of breathing (paradoxical breathing, accessory muscle use) or other signs of distress (diaphoresis, agitation)
If successful If unsuccessful
Proceed with extubation Repeat trial daily & gradually withdraw ventilation support
(pressure support & T-piece weaning equally efficacious & superior to IMV wean)