Preventive role of hydergine in fentanyl deaths?

I just published a post discussing the possible role of hydergine for Alzheimer's, and also more importantly in delaying brain deaths from cerebral anoxia- specifically the so called "cat experiment"   also  reading its usage by European surgeons of a modified-procedure were they give there patients hydergine prior to  undertaking major surgeries on their patients.  For details I did not review these experiments  on these usages only their  citations in the textbook by Pearson and Shaw entitled "Life Extension " and also  the small textbook  by the Life Extension Foundation  entitled "The Physician's Guide to Life Extension Drugs. In the latter citation the reader will find 10 pages of this 268 page booklet devoted to this drug.
Most people are unaware that in the 1980's hydergine was  the fifth most commonly prescribed drug in Europe. In my  2010  year copy of CPS ( Compendium of Pharmaceuticals and Specialties )-the medical doctors pharmaceutical reference bible on drugs-  only 3 lines of  a single column of over a 2778 page double column book is devoted to this drug with the headlines on page 1091 reading   " Adjunctive Management of idiopathic Dementia "