Just like Vallar said, you'll need to do float compare.
Set it up with multiple events sending to different states
State [Health Check]
Events Full Health -------> [Full Health State]
75-99 Health -------> [High Health State]
51 - 74 Health ------> [Medium Health State]
1 - 50 Health -------> [Low Health State]
Have the float compare, compare your current global health float to set variables that you will have to create. Then based on the comparison, greather than, equal to, less than, set them as above stated events which will sent it to the new states (full, high, medium, low) and in these states you will then apply whatever action you wanted the trigger to say/do.
Hope that clears things up a bit.