To add some numbers to the answers...
I have 1059 assets on the asset register which I'm responsible for, this includes 4 theatres' equipent (cardiac incl), 3 ITU's (mainly monitoring and ventilators) and over 250 infusion devices. With the current set-up which we've optimised over and over again it seems we are still 30%-40% short on human resources.
Rule of thumb in our case is at least one engineer per site and probably no more than 800 assets(depending on quantities of type) per engineer.
