Flight Attendant reported she had no confidence in her ability to evacuate a 600 LB passenger in the event of an emergency.

Narrative

A passenger weighing approximately 600 LBS was boarded by lift. [The passenger] was placed in a row of 3 seats. [The passenger] was not able to slide over to the window; so [the passenger] remained in the aisle seat. Five seatbelt extensions were required. I am reporting for one obvious reason. There was NO way I could have evacuated this passenger of size. [The passenger] could barely walk; and [the passenger's] size would not allow egress through the windows/doors. When we landed; a group of rampers were removing [the passenger] from the seat; and due to [the passenger's] size/weight; [the passenger] fell down. [The passenger] also was attached to a visible catheter and required 3 O2 bottles. In my opinion; this should have been a MedEvac. This passenger's needs were not met while traveling on a commercial aircraft. From what I observed; our rampers are not trained in the proper handling of a person of size. The rampers are trained to handle cargo/baggage not passengers of size. From my standpoint as a trained safety professional; the aircraft doors and windows are NOT big enough for a person of [this] size to evacuate successfully.