I teach IV fluids to every third year medical student and resident that crosses the threshold at St John Hospital. It’s what I do. It’s a conventional lecture focusing on the expected fluid distribution following various flavors of IV fluids.
The dogma of IV fluids is that dextrose solutions, crystalloids and plasma expanders distribute across the body compartments in unique ways.
Dextrose solutions distribute like total body water, with two thirds disappearing into the intracellular compartment and the remaining third distributing one part to the plasma compartment and three parts to the interstitial compartment. So approximately 80 milliliters of a liter of D5W remains in the plasma compartment.
Isotonic saline is trapped in the extracellular compartment and one quarter of it expands the plasma compartment. So one quarter of a liter of isotonic saline remains in the plasma compartment.
Plasma expanders are locked to the plasma compartment so one liter of albumin expands the plasma compartment by one liter.
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| from the label of 4% albumin, the co-star of the SAFE trial |
So in summary:
- one liter of dextrose expands the plasma compartment by 80 mL
- one liter of 0.9% saline expands the plasma compartment by 250 mL
- one liter of 4% albumin expands the plasma compartment by 1,000 mL
