What is the purpose of spontaneous breathing trials in ventilated patients?

• A. To test maximum ventilator support
• B. To assess readiness for extubation
• C. To evaluate oxygen toxicity
• D. To measure airway resistance only

Answer: (B)

Spontaneous breathing trials test whether a patient on mechanical ventilation can breathe safely without substantial ventilator support, which helps determine readiness for extubation. During an SBT, support from the ventilator is reduced or removed for a set period (often using minimal pressure support, CPAP, or a T-piece) while closely watching how the patient handles breathing, gas exchange, and circulation. If the patient maintains adequate oxygenation and carbon dioxide levels, keeps breathing efforts manageable, and remains hemodynamically stable without signs of distress, they are likely ready for extubation. If they show excessive work of breathing, tachypnea, hypoxemia, hypertension or hypotension, or changes in mental status, the trial is not tolerated, and more time on ventilation with re-evaluation is needed.