So who is clever with CPP an MAP and stuff? So I attended a job the other day and my current level of knowledge is not good enough to work this out:

40F. FAST +ve, blown pupil, GCS 14 (3,5,6) when lying down, GCS 8 (1,4,3) when upright with full decorticate rigidity, dropping BP.

I have subsequently found out she had a bleed 2° to metastatic deposits.

But I don't understand why her BP was dropping. It went from 130/115 down to 87/73. 

I understand that CPP = (dBP+1/3(sBP-dBP)) - ICP and that CPP should be roughly 70mmHg. But if this is the case, why would her BP drop if her ICP was raised?

Also, fluctuating GCS with patient position? Whats that all about? 

Any insight would be gratefully received :)