After the patient is removed from the ventilator but the endotracheal tube cannot be extubated, the operator will let the patient breathe in a T-tube. The T-tube can breathe through a tracheostomy tube or through an endotracheal tube.

For patients on long-term mechanical ventilation, weaning off mechanical ventilation using PSV, or difficult or failed trials of CPAP or T-tube, SIMV is the appropriate method to choose.

Currently, patients on ventilators, weaned off ventilators by CPAP or T-tube trials are often used clinically to avoid hospital-acquired infections, lung damage due to ventilators, expensive treatment costs leading to difficulty in weaning off ventilators and the patient's risk of death.