P0.1 and Extubation Failure in Critically Ill Patients

Weaning protocol SBTs will be performed in semirecumbent patients on Pressure Support Ventilation (PSV) mode with inspiratory pressure of 5 cmH2O and positive-end-expiratory pressure (PEEP) of 5 cmH2O as per ICU protocol. Inspiratory oxygen fraction (FiO2) will be adjusted for the achievement of an arterial oxygen saturation value \> 90%, as measured by pulse oximetry. The SBT duration will be 30 minutes as per ICU protocol. The criteria that will be used for poor SBT tolerance are: (1) diaphoresis; (2) use of accessory respiratory muscles; (3) RR \> 35/min; (4) oxygen saturation by pulse oximetry \< 90% with FiO2 ≥ 50%; (5) HR \> 140/min or greater than a 20% increase from baseline; (6) Systolic blood pressure \>180 mmHg or \<90 mmHg; (7) development of cardiac arrhythmias; and/or low level of consciousness. The decision to stop SBT will be made by the physicians. Patients who will fail SBT will be shifted to their previous ventilator mode and not be enrolled in the study. Patients who will complete the SBT will be extubated and followed-up for 72 hours. The medical team (physician, nurse, and respiratory therapist) involved in the extubation decision will be blinded to the P0.1 results. EF will be diagnosed if the patient is extubated but required reintubation within the following 72 hours. Criteria for acute respiratory failure after extubation are the development of at least one of the following: (a) respiratory acidosis with pH \< 7.32 and arterial CO2 pressure (PaCO2) \> 45 mmHg; (b) arterial oxygen saturation \< 90% with FiO2 \> 0.5; (c) RR \> 35/min; (d) clinical signs of respiratory fatigue. The management of post-extubation respiratory failure will not be protocolized and will be left to the physician's discretion. Ventilatory, including P0.1 and hemodynamic parameters, including EtCO2 will be recorded as the average of at least three measurements immediately before SBT, during SBT, and at 30 minutes after SBT initiation. Arterial and central venous blood gas (if central line present) will be measured immediately before SBT and at 30 minutes after SBT initiation.