Well, you've already put MOST of the Spoilers up, so...
(spoiler ahead)
Dissolve from Karloff's last dying words to-the very Surgical Theater where Karloff practiced and lectured, an indeterminite period later...the resident Surgeon has successfully operated on a blissfully unaware patient. Karloff's tragic experiments in Anesthesia have reaped dividends for medical science. The End.
As far as the Title, no one actually explains the "corridors of blood" in the film (not that I recall, it was over 5 years ago I saw it), but Surgery at that point in History was more butchery than medicine. Just as the film hinted at, Surgery consisted mostly of holding patients down and cutting them while they struggled and screamed...if you were lucky, they'd go into shock and you could make some accurate cuts and sutures before they died of bloodloss. Don't forget this was the period before Lister, so chances were high that Surgical incisions became Septic....
Corridors of Blood indeed.
Also, is the relevance of the title ever explained?
