Fig 2. Problem definition using the PEEP value.
Illustration of the problem statement with progression of a single patient’s PEEP-level during a stay in the ICU. In this regard, the event is the time at which the PEEP-level is decreased. Any PEEP-level decrease that is followed by an increase to at least the same level as before refers to a failed weaning (red triangle). A PEEP-level decrease without further increase to a previous level until the end of the ICU stay refers to a successful weaning (green triangle). Hence, in this figure there are one failed weaning and two successful weaning attempts.