Hi Bonnie
Not sure if you're still here and realise this is years late however thought I might reply for those who still have this problem. This is a very common problem with no easy fix, generally if you have smaller IV bags (100ml) it is best to use them but use what you've available, time and date. Puncturing IV bags as frequently as is required to create flushes poses an infection risk and the port isn't designed for this, usually it becomes damaged before you have removed all the fluid. And need to be cautious/aware educate on IPC practice.
However there is another option which MAY be possible to organise... Again it's not something thats likely to be available immediately but it might be more sustainable for the future. If you can organise it and it's not possible to get ampules. There is a spike port which makes the system closed and no needles involved which would be less risk than repeated needle spiking. I am not 100% sure of how long this can be used for etc. And the best option remains single use amps/prefilled syringes.
I've attached a picture below. This may be an option for places where saline ampules are unlikely to become available anytime soon.