Something to think about...
Remember right before the lava pit there was a caged supply room full of health, armor, and shit loads of ammo. There was more stuff in there than you could even possibly hold. Why would they do that? It got me thinking then I noticed the chair... I pushed that sucker all the way down the hall and into the door entering the lava pit stuck it in and jammed the door up so it wouldn't lock as I entered the lava pit. Now I could make runs back to the room ans use the extra health and ammo. Made the lava pit a helluva to easier and I think they might have intended you to do this considering there was only one chair [knocked over on it side in the middle of the room] and they gave you more health than you could possibly pick up in one refill...
Think outside the box.
[probably just all those adventure games bubbling up inside of me.]