Design: Randomized Clinical Trial. Methods: This study will include patients with COPD, admitted to the Intensive Care Unit of Hospital Nossa Senhora da Conceição, undergoing MV for at least 48 hours. When considered by the care team ready for SBT, they will be randomized to one of the following strategies: SBT in Pressure Support or SBT through "T" Tube. The primary endpoint of this study will be the reduction in the days spent on MV. Other outcomes measured will be mortality, extubation and success rate, time to weaning of MV, length of ICU stay and incidence of tracheostomy.