Various disease states predispose patients to respiratory failure ultimately requiring mechanical ventilation for respiratory support. In patients with sepsis, the need for mechanical ventilation may be prevented by instituting early aggressive resuscitative measures [1]; however, this protocol-based care may not result in improved outcomes [2, 3]. Similarly, instituting non-invasive ventilation in patients with acute cardiogenic pulmonary edema or acute exacerbation of chronic obstructive pulmonary disease could reduce the need for intubation and mechanical ventilation in these patients [4–7].

Once a patient has been intubated, several strategies which could speed up readiness for liberation from mechanical ventilation include the use of lung protective ventilation in ARDS [8], interruption of sedatives on a daily basis [9], implementing physical and occupational therapy early [10], conservative fluid management in ARDS [11] and the prevention of ventilator-associated pneumonia [12].

Patients determined to be ready for a trial of spontaneous breathing should exhibit improvement in the underlying factors that led to respiratory failure and be hemodynamically stable with a ratio of partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO₂/FiO₂) that exceeds 200 on a positive end-expiratory pressure (PEEP) of 5 cmH₂O or less [13].

An SBT is performed to demonstrate the patient’s ability to breathe on minimal or no ventilator support for at least 30 min. Usually, this is performed on continuous positive airway pressure, low-level pressure support or utilizing a T-piece. The occurrence of oxygen saturation ≤90 %, heart rate >140/min, respiratory rate >35/min for more than 5 min, a sustained variation of 20 % or more in the heart rate, systolic blood pressure below 90 mmHg or exceeding 180 mmHg, increase in anxiety or diaphoresis all portend failure [13].

A successful trial of spontaneous breathing will lead to an evaluation of the patient’s ability to effect airway protection upon removal of the endotracheal tube. This assesses the patient’s mentation, strength of cough and quantity of airway secretions. Demonstration of adequate unassisted breathing and airway protection should prompt immediate removal of the endotracheal tube. Otherwise, if SBT is unsuccessful, re-initiation of mechanical ventilation at the prior support level should be ensured while a careful investigation is performed to determine and treat the underlying reason for failure before repeating an evaluation for a trial of spontaneous breathing again [13].

Demonstration of some capability to interact with the health care team is required prior to removal of the patient’s endotracheal tube. However, the exact significance and the degree to which it plays a role in successful extubation remain controversial [14]. It has been suggested that in patients capable of protecting their airway, a Glasgow coma scale score of ≥8 predicts successful extubation [15]. Prolonged mechanical ventilation, female sex and traumatic or repeated intubation have all been associated with post-extubation upper airway obstruction [16] leading to suggestions for the use of the cuff leak test (air leak detection during mechanical ventilation with a deflated endotracheal tube balloon) in these patients to assess the patency of the upper airway prior to extubation [17]. Patients at high risk of post-extubation stridor were identified in a single study of intubated medical patients using a cuff leak of <110 ml within 24 h of extubation [18]. Steroids and/or epinephrine may be used during this period to reduce the risk or for treatment in those patients who develop stridor afterwards [19]. The use of NIPPV and/or heliox has also been advocated [19].

The use of weaning protocols enforces daily evaluation of readiness for extubation by using pre-specified criteria and implementing trial of spontaneous breathing in a structured form. The WEAN study, a multicenter, randomized controlled trial which compared automated weaning with the use of a standardized protocol demonstrated significantly faster liberation from mechanical ventilation and fewer cases of protracted ventilation or tracheostomies [20]. Similarly, a large Cochrane meta-analysis of ten trials compared automated weaning protocols and non-automated weaning strategies and demonstrated a decrease in the duration of mechanical ventilation, time to successful extubation, ICU length of stay and proportion of patients on mechanical ventilation for more than 7 days in patients on a protocolized weaning strategy [21]. Though yet to be widely adopted, this automated strategy possibly ensures all mechanically ventilated patients are given a fair chance to demonstrate their ability for spontaneous breathing at the earliest time (Figs. 31.3 and 31.4).

Procedure to be implemented by physician or appropriately certified healthcare professional after eligibility has been determined following collaborative daily assessment by nursing and respiratory therapist. Necessary equipment and personnel confirmed to be available and responsible physician notified.