AB - sorry to hear of your kitty's health issue.
I can't help you with the technical part of your questions.....but looks like these are available from Chewy with an Rx, which I'm sure your vet could provide. Delivery by Chewy would save all that driving anyway.
https://www.chewy.com/icu-medical-lactated-ringers/dp/173586?gad_source=1
I am not a vet or even some kind of expert, so naturally what I post should be verified and confirmed by your choice of practitioners.
Good luck to your little one!