Invasive mechanical ventilation for \>48 hours,

patient is ready for SBTs for assessment for extubation,

has a normal sinus rhythm at time of SBT (no pacemaker),

is tolerating pressure support ventilation ≤14 cm H2O (SpO2 ≥ 90% with FiO2 ≤ 40% and PEEP ≤ 10 cm H2O),

hemodynamically stable (low or no vasopressors), stable neurological status (no deterioration in GCS during prior 24 hours \& ICP \< 20),

intact airway reflexes (cough \& gag).

Weaning And Variability Evaluation