Let’s say you’re asked to write orders for IV fluids. Sounds simple enough, right? Then you click on the menu of choices and there’s twenty options to choose from. Which is the right one?!
Here are two basic rules to follow:
Match the IV fluid to osmolality. The average serum osmolality is about 300. This chart provides a helpful overview of the osmolality of different IV fluids, like normal saline (310) or D5W (253, and 170 kcal). This is important for conditions like hyponatremia, in which choosing the wrong IV fluid can be dangerous. Although normal saline can correct hyponatremia in cases of dehydration, normal saline actually causes a paradoxical reaction in SIADH, and can cause hyponatremia to get worse!
Match the rate and volume to volume status. Equally as important is how quickly fluids run and how much you give. There are certain conditions like CHF where you want to be careful about how much fluids you pump into a person, and will want to run the fluids slowly, say, 500 cc over 4-5 hours. There will be other scenarios where you are resuscitating someone in sepsis and may run a liter of normal saline over 30 minutes.