Potassium either comes pre-added or can be manually added to any intravenous solution at a concentration of 2 mEq/100 ml or 20 mEq/L to provide the appropriate amount of K for maintenance. The maintenance K requirement is estimated at 2 mEq/100 ml of fluid or 20 mEq/L. Combine this with hypotonic IV fluids, and you have a perfect formula for hyponatremia. The more ADH, the more water is reabsorbed from the collecting duct of the kidneys. All of these things cause an increase in ADH release. They are vomiting, or have respiratory illness, or require surgery, or have fever. We know that kids in the hospital are stressed. Reference: AAP Guidelines on Maintenance IV Fluids in Hospitalized Children Based on current research, it is determined that giving hypotonic solutions as maintenance IV fluids is associated with severe morbidity and even mortality due to hyponatremia. Note that all of these are considered hypotonic to plasma. (154 mEq/L divided by 5 is roughly 30 mEq/L).įor decades, our maintenance IV fluids have ranged anywhere from 1/5NS to 1/3NS to Ѕ NS. So if we wanted to add 30mEq/L of Na, we would need 1/5NS. When we speak about adding sodium to IV fluids, we talk about it in terms of normal saline. For an adult, this will provide about 75 mEq of Na/day, equivalent to approximately 4.5 G of salt. So, Na is added to maintenance fluids at a concentration of 3 mEq/100ml or 30 mEq/L. Holliday and Segar decided on this number by looking at the sodium content of human and cows' milk. Salt intake => increase in plasma Na and osmolality => increased thirst and increased ADH secretion => chug-a-lug => water intake and water retention, plasma dilution => plasma Na and osmolality decline almost to baseline at the expense of expanded plasma volume (I cannot take off my rings socks leave deep marks on shin!) => the kidney stops making renin => no renin, so no angiotensin and no aldosterone => Na re absorption declines in the collecting duct => urinary Na excretion increases until all the salt from the pizza has been excreted => plasma osmolality falls as Na is excreted => ADH shuts off => water is excreted until plasma volume has declined to baseline.īased on recommendations made by Holliday and Segar, the daily sodium requirement was estimated at 3 mEq/100 ml of water water requirement.
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