Saline versus balanced solutions: are clinical trials comparing two crystalloid solutions really needed?

Some of our colleagues believe that everything should be tested in prospective, randomized clinical trials. Some of our colleagues also believe that so-called pragmatic trials can help improve the care of critically ill patients. The designs of such studies are based on the postulate that patients are all the same and will be globally either improved or harmed by one strategy compared with another. This may be true for some interventions but is certainly not true for all, including choice of crystalloid solution.