Weaning from mechanical ventilation should be considered when the disease process prompting intubation has improved. Daily screening of intubated patients for weaning potential should be performed. Several studies show that most patients on mechanical ventilation should have scheduled spontaneous breathing trials (SBT) following daily sedation breaks(Zakhary & Uppal, 2017). Aside from the improvement of the primary etiology of the disease process, the patient should be alert, following commands, initiating breaths, able to hold their head up, able to cough with the recent PaO2 ≥ 60 with FiO2 ≤ 40% and PEEP ≤ 8 and needs suctioning ≤ every 4 hours, and hemodynamically stable with minimal pressor support before considering extubation(Zakhary & Uppal, 2017). Daily SBT should involve at least 30-120 mins of breathing without significant ventilatory support, specifically the use of either an open T-piece breathing system or minimal amounts of ventilatory support such as pressure support to overcome the resistance of the ETT or low levels of CPAP(Jameson et al., 2020). However, the patient must initiate all breaths and control tidal volume. A successful SBT is where the patient continues to breathe without distress with stable vital signs and a stable arterial or ETCO2 tension. Tachypnea, hypoxemia, tachycardia, bradycardia, hypotension, hypertension, increased anxiety, or diaphoresis are some indications of SBT failure(Jameson et al., 2020). Other risks during the weaning process are unplanned extubation, especially when the patient becomes suddenly very restless and agitated and develops dysrhythmias. If the SBT is successful, rapid shallow breathing index (RSBI) or f/VT, calculated as a respiratory rate per min divided by the TV in liters, should be done at the end of SBT, which can be used to predict weanability. An RSBI of <105 at the end of SBT warrants an extubation trial(Jameson et al., 2020). Despite a thorough weaning trial, patients may still develop respiratory distress after extubation and may require a reintubation.
Jameson, J. L., Fauci, A. S., Kasper, D. L., Hauser, S. L., Longo, D. L., & Loscalzo, J. (2020). Respiratory failure. In Harrison’s Manual of Medicine (20th ed., pp. 75–76). McGraw Hill.
Zakhary, B., & Uppal, A. (2017). Mechanical Ventilation. In S. C. McKean, J. J. Ross, D. D. Dressler, & D. B. Scheurer (Eds.), Principles and practice of hospital medicine (2nd ed., pp. 2524–2541). McGraw-Hill.