Quote from Sweet_Wild_Rose
Fluid warmer. Temps are set at 104, bottles are labeled with the date they must be used by (3 weeks) and get refilled daily. Ours are similar to this, but have two units- one for fluids and one for blankets.
We have the same thing, however, ours is set at 103. It looks like a large steel refrigerator. Top part is for bottles of saline, bottom is for
blankets. And we date them and rotate them out...but we usually use them before they even get close to needing replacement.
I honestly don't think microwaving is ever safe. You have no way of determining if it was heated evenly, which could cause extremely hot spots. And like you mentioned, you don't know if the bottle has broken down at all into the solution.