Go downstairs and save the game in the next room.
Go to the next room - and solve the puzzle.
This pole has three switches and one hole. Here is the proper sequence:
Left switch -a knight
Right switch - nothing (no symbol)
Middle switch - a coffin
Put the hand into the hole and jump into it after the cutscene.
There is the save point at the eastern end of this room.
There is also a narrow passage in the western part of this area. Go forward until you reach the room with two Needlers. Wheeler will kill them. Go to the "boss door" but don't open it yet. Go north and take First Aid Kit, Health Drink and save the game. Now enter to fight with Asphyxia.
This monster can be very annoying - she can grab Alex and kill him immediately. Don't use the gun during this fight - it's useless. Pick the axe and avoid her blows changing sides from left to right. You will need some luck to find yourself near her tail. The X marker will appear - hit her then and quickly move to her head. You should be able to finish her off then.
Xbox 360: killing of Asphyxia will give you the Catch Your Breath achievement (50 p.).
Leave this place through the window after the fight.