The following objectives were used for comparison: 1) primary objective: reintubation rate during hospitalization; 2) secondary objectives: length of hospitalization at the Coronary Care Unit; time from intubation to start of weaning; time from start of weaning to extubation; time from SBT and extubation; presence of respiratory infection in patients requiring reintubation; mortality of patients requiring reintubation.

Once the cause leading to the need of MV was resolved, patients from both groups underwent a daily clinical evaluation in the mornings, to determine whether they were ready for mechanical ventilation weaning, according to the following clinical SBT criteria: 1) Cause of MV: resolution of the cause and abnormalities leading to MV; 2) neurological stability: patient awake, without or with minimal infusion of sedatives/narcotics, with effective cough and Glasgow scale ≥ 9; 3) cardiovascular stability: mean blood pressure (MBP) ≥ 60 mm Hg, without vasopressors or with low vasopressor doses, heart rate (HR) ≤ 140 / min, hemoglobin (Hb) ≥ 8,0 - 10,0 g/L, partial arterial oxygen pressure (PaO2) ≥ 60 mm Hg with fraction of inhaled oxygen (FiO2) ≤ 0.4, oxygenation index (PaO2 / FiO2) ≥ 150 - 300 without significant respiratory acidosis; 4) metabolic stability: temperature < 37.8° C (armpit) and lack of hydroelectrolytic disorders.

Inclusion Criteria:

• patients hospitalized at the CCU with MV for over 24 hours;
• age over 18 years;
• both genders;
• patients capable of spontaneous ventilation;
• patients with indication for MV weaning.

Exclusion Criteria:

• conditions and/or circumstances that might result in difficulty to understand the informed consent (psychiatric disorder, alcohol or drug addiction, mental disability);
• patient denies to sign the informed consent;
• end-stage diseases and
• dependence on mechanical ventilation.