Classification of patients according to the weaning process
| Group/category | Definition |
| Simple weaning | Patients who proceed from initiation of weaning to successful extubation on the first attempt without difficulty |
| Difficult weaning | Patients who fail initial weaning and require up to three SBT or as long as 7 days from the first SBT to achieve successful weaning |
| Prolonged weaning | Patients who fail at least three weaning attempts or require >7 days of weaning after the first SBT |
SBT: spontaneous breathing trial.