Gareth Benbow, 33, of Inverness, was accused of having a vendetta against Raigmore Hospital in Inverness.
Sheriff Margaret Neilson said medical staff had saved his life on 19 occasions following numerous overdoses.
Jailing Benbow for two years and five months, she said he had a "misguided view" he was not treated properly.
A jury at Inverness Sheriff Court took less than 40 minutes to unanimously convict Benbow of the malicious call, following a two-day trial.
The court heard that staff and visitors who were evacuated from the hospital on 24 August last year.
The patients included eight people receiving treatment in intensive care, nine in a cancer ward and 10 children.
A member of staff who had previously dealt with Benbow recognised his voice in the hoax call. He denied making the threat.
Sentencing Benbow, Sheriff Neilson told him: "The staff in the intensive care unit had saved your life on 19 occasions after your numerous overdoses.
"You have a misguided view that you have not been treated appropriately by doctors in the past and appear to be pursuing some kind of vendetta against Raigmore Hospital and those who work there."
A man who made a bomb threat which led to more than 20 patients being evacuated from a hospital has been jailed.