No filters left? Suffocating, yet? Try to drown yourself; when you lift yourself up from the water, the short choking timeout will be reset.
Metro is a brilliant game from all perspectives (perhaps the Fallout 5 of 2019); the single most annoying flop of the entire game is perhaps the final bear fight. The bear cannot be defeated by dealing damage. You can also try to do it like they do in the movies and stay close to the edge of the platform; however it seems that a 5 ton bear has instant deceleration (nevermind the momentum that a huge bear must have after running a stretch) and will not fall off the platform.
Perhaps the safest recipe is the following:
after which, a cutscene will trigger.
The bear cannot reach the player behind the wooden wheel and right on the edge of the platform. It will just stay there, growl, scratch and take bullets to the head. It is not certain how much damage must be dealt and there is no apparent indicator that the bear had enough and it's time to let you wallop you right into the cutscene.
Most likely the developers thought that it would be "realistic" to have the player both fight the bear and probably think about letting the bear run off the edge of the platform. Unfortunately, nothing is in the least realistic about that bear as emphasized formerly. . .