Nah, once they see you, you either kill them or use the Blink skill (the teleport) to move somewhere where they can't reach you, then wait until everything goes back to normal - however enemy patrols will slightly change, most of the times for the worst.
The low-chaos ending doesn't exactly require 0 kills, mind you. I killed around 20+ enemies and I could still get the good/not-chaotic ending.
The tallboys, those guards using the robo-walker things, cannot be taken down throughout non-lethal ways, which sucks.