How Much Peep Is Too Little?

Many people, their process for managing peep is to go up to whatever the patient needs and then to very slowly wing it over a period of days. You can imagine if for any reason you had a patient on far too much peep, what is that going to mean for their trajectory of their mechanical ventilation? The other possibility we didn't mention was that the patient is hypoxic for a reason which is not related to airspace disease. They have a lot of well ventilated lung but they're hypoxic for some other reason. But again these are not diseases that will improve and in fact maybe harm by additional peep.