When in battle, make sure that you always have a elder vitae blood pack in your inventory so that if your life or blood stock was low then you can just equip a elder vitae pack which will raise both bars fully. You can only spawn one pack when using cheats so make sure that you spawn one straight after using the one in your inventory. The quick way to spawn a elder vitae blood pack is to push "~" and then type in "give" space and then "i". You can then push the down key three times and then push enter.
Have fun!!!!