I don’t give the claim much weight, but someone made a claim in a thread elsewhere on the zombie show Fear The Walking Dead that this is the accepted course of action if medical staff must abandon a hospital with no continuity of care and no hope of rescue.
NOW maybe I could see this being the truth for patients on life support or feeding tubes etc that absolutely will not survive, but no way in hell for anyone else. For instance one of the character’s medical issue is heroin withdrawal.
So I believe this is either a lie or a misinterpretation.
Here is an article I found that says during Katrina they actually debated doing it to patients who would not otherwise survive the ordeal, a big qualifier.
It was illegal, there was (and probably never will be) any protocol that states anything like this, and in the Memorial Hospital scenario, there was actually no need to do it any case as rescue was ongoing.