Hello
In answer to the orginal question; i looked into the same issue a few months ago. I couldn't find any regulations, a Trust policy or a procedure on infusions (other than those specific to a particular procedure (Epidural) or specific drug use (Rheumatology)).
However i spoke to our Nurse Education Department who said that the advice from several sources UCL, British National Formulary, Safety In Doses, RCN Standards for Infusion Therapy (titles from memory) appeared to be that all medicines should be controlled, and preferably all infusions should be controlled.
In particular the British National Formulary instructs on how medicines should be given. I was also told that too much saline delivered too quickly can be fatal (although I don't recall whether this is specific to certain medical conditions).
Lee