You would think, in chasing blood pressure and potassium levels with the appropriate drugs and repletion solutions, that things would eventually stabilize. The human body, contrary to what you might think, has its own way of doing things--and this "own way" will cause more trouble (in terms of lab draws and brain-ache) than you ever expected.
Just because it's easy doesn't mean it's right.
Yeah, it's easy to replete a low sodium, but what happens if the paramaters the doctor ordered are wrong, wrong, wrong for that particular patient? Oops. Time to run the hypotonic solutions again!
You can't always get what you want.
Even if what you want is normal serum values and normal ABGs. Sometimes people have their own ideas.
Life is not fair, and nobody ever said it was.
Sometimes, no matter how hard you try to resuscitate a patient, that patient will simply not do what you want them to do.
Lesson learned: The human body tends toward stability, unless it gets a wild hare and decides not to.