Spontaneous breathing trials (SBTs) assess readiness for extubation, yet the use of conventional parameters used to establish weaning success may be elusive, especially in high-risk patients. Currently, non-invasive techniques allow comprehensive bedside assessment of advanced respiratory mechanics, including metrics of respiratory system compliance (CRS), respiratory muscle effort (POCC) and respiratory drive intensity (P0.1). This study investigates whether these measurements during SBT may improve the prediction of extubation outcomes

To be eligible, patients had to meet all of the following criteria:

1. Age ≥ 18 years.
2. The presence of ≥ 1 among the following factors to define the high-risk for re-intubation: age older than 65 years; heart failure as the primary indication for mechanical ventilation; moderate to severe chronic obstructive pulmonary disease (COPD); an Acute Physiology and Chronic Health Evaluation II (APACHE II) score higher than 12 on extubation day; body mass index of more than 30; inadequate cough reflex or suctioning >2 times within 8 hours before extubation; prolonged use of invasive ventilation (≥ 7 days from the first SBT); more than 2 comorbidities categorized based on the Charlson Comorbidity Index.
3. Deemed ready to be weaned from the ventilator, based on the following criteria: (a) invasive mechanical ventilation for more than 48 hours, including at least 12 hours of pressure support ventilation with PEEP ≤ 8 cmH2O and pressure support ≤ 10 cmH2O; (b) Improvement of the condition leading to intubation; (c) patient making inspiratory effort; (d) adequate gas exchange, as indicated by a ratio of partial pressure of arterial oxygen (PaO2) to inspiratory fraction of oxygen (FiO2) ≥ 150 with FiO2 ≤ 40% and arterial pH within normal range (7.30 - 7.50); (e) Glasgow Coma Score higher than 13; (f) a core temperature below 38°C; (g) Richmond agitation and sedation scale between -1 and +1.

Eligibility required readiness for scheduled extubation after successfully completing a 30-minute SBT in the pressure-support mode (7 cmH₂O)

SBT success was defined by the following criteria [19]: (a) adequate gas exchange, as indicated by a ratio of partial pressure of arterial oxygen (PaO2) to inspiratory fraction of oxygen (FiO2) ≥ 150 with FiO2 ≤ 40% and arterial pH within the normal range (7.30 - 7.50); (b) respiratory rate < 35/min; (c) spontaneous tidal volume higher than 5 ml of predicted body weight (PBW); (d) a ratio of respiratory rate to tidal volume (i.e. the rapid shallow breathing index, RSBI) < 105/min per liter; (e) systolic blood pressure between 90 and 160 mmHg and heart rate < 140/min, with or without low doses of vasopressors (< 0.5 mcg/kg/min). Exclusion criteria were tracheostomy, patients undergoing withdrawal of life-sustaining treatments, known neuromuscular diseases.

High-risk patients for re-intubation were defined as follow :

The presence of ≥ 1 among the following factors to define the high-risk for re-intubation: age older than 65 years; heart failure as the primary indication for mechanical ventilation; moderate to severe chronic obstructive pulmonary disease (COPD); an Acute Physiology and Chronic Health Evaluation II (APACHE II) score higher than 12 on extubation day; body mass index of more than 30; inadequate cough reflex or suctioning >2 times within 8 hours before extubation; prolonged use of invasive ventilation (≥ 7 days from the first SBT); more than 2 comorbidities categorized based on the Charlson Comorbidity Index.