ICU rounds is a production of the Society of Critical Care Medicine.

Welcome back to surgical ICU rounds.

My name is Dr. Jeffrey Guy.

Today I want to talk about something we discuss frequently in rounds in intensive care unit,

and that is what exactly is a colloid.

I hear that term getting thrown around a lot,

and it seems a lot of times as we're throwing that term around, we don't have a real good understanding of it. I like to think that a lot of

what we do in the intensive care unit, at least the biology and the chemistry, is really strongly

founded on what I learned in high school science. It doesn't seem to be, you know, I really am in the opinion

that a lot of the care decision, the science,

isn't that high brow.

It's very basic elementary science.

And one of the first things I learned

in my ninth grade biology class

was the concept of osmosis.

And osmosis was defined then at that point in time,

is the movement of water across a semi-permable membrane, easy for me to say.

Well, we'd like to say that osmosis is the movement of water through a semi-permable membrane

from an area of high concentration of solute, so low concentration

of solute, into a region of higher concentration of solute, basically bringing those concentrations

on either side of that membrane into equilibrium. Now often when we're talking about the use of

intravenous fluids, the topic of using a colloid will come up. And whether a

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