A spontaneous breathing trial (SBT) is a test whereby patients attempt to breathe independently, while usually still connected to ventilators. It can predict whether they have the ability to successfully wean.2 Postop patients who meet all of the weaning criteria may be extubated after a single trial. Depending on the patient's lungs, trials may be as short as five to 15 minutes, and repeated up to four times a day. There are a number of ways that this can be done, but first, you'll need to help the individual prepare mentally.