Composition of default fluid replacement solutions

Simon Oczkowski, MD, MHSc, MSc, is a critical care clinician and an associate professor of medicine in the Division of Critical Care at McMaster University. His clinical and research interests include end-of-life care and decision-making, organ donation, and patient and family engagement. He has developed guidelines for the Society of Critical Care Medicine and European Society of Intensive Care Medicine.

What is the default fluid replacement solution that you use? Do you include potassium in your default IV fluid treatment?

Simon Oczkowski, MD, MHSc, MSc: When it comes to maintenance fluids in hospital, I think the first and most important thing to think about is why does a patient need maintenance fluids at all? In general, what we’re finding is that too much fluid is also harmful for patients, and we should be viewing fluids as a drug or another medication, where you can actually overdose and cause harm by providing it. So, the first thing to think about is why does the patient need maintenance IV fluids?

If it’s a patient who has reduced oral intake, perhaps they are post operative—patients like that are the ones who would typically need IV maintenance fluid—commonly what I see is patients get prescribed maintenance fluid when they come into the emergency room, and people forget to use it and reduce the amount later on. The thing I suggest to most of the trainees I work with is that instead of using IV maintenance fluid, you should be using IV maintenance feeding. Make sure the patient has enough to eat, has enough to drink, and you’re removing any barriers to nutrition. And it is only in those remaining patients where IV maintenance fluids are needed.

In that group of patients who are not able to eat or drink for a prolonged period of time, you need to provide water, you need to provide electrolytes, and you need to provide some glucose. There are many calculators and equations available online to help you choose which solution might be best. However, what I find is that most hospitals will have 1 or 2 fluids available that include all of these. So, typically in my hospital, for instance, we have 2/3 and 1/3, so that includes glucose, that includes sodium, and then I also add into that usually 40 mEq/L of potassium, and that comes in the bag.

But what fluid is available in your hospital might vary, so rather than getting too specific about the calculations, you need to actually see what’s available in your intensive care unit (ICU), on your ward, and provide something. But in those patients with maintenance fluids, I usually use something like 2/3 and 1/3, with 40 mEq/L KCl, in order to provide water, electrolytes, and glucose.