IV Fluids and Electrolytes!

Question 1

Why is “normal” saline not really physiologically normal?

Answer 1

NS contains more chloride than plasma does.
In comparison, the chloride content of serum is normally 99 - 109 mmol/l, while the chloride content of NS is 154 mmol/l.

Question 2

How does the amount of elemental calcium differ between calcium chloride and calcium gluconate?

Answer 2

1 g of calcium chloride contains 3x as much elemental calcium as 1 g of calcium gluconate.

[From UpToDate, drug information;
1 g calcium gluconate = 93 mg of elemental calcium
1 g of calcium chloride = 270 mg of elemental calcium]

Note: calcium chloride is preferably administered via central line as it is more irritating to the the veins than calcium gluconate

Question 3

In regards to the osmolality of IV solutions, the osmolality as measured in vivo is…

Answer 3

…more important than that measured in vitro.

Question 4

A 5% dextrose solution in water (D5W) is isotonic in vitro, but…

Answer 4

…the in vivo effect is that of pure water because the glucose is rapidly metabolized.

(From PubMed, http://www.ncbi.nlm.nih.gov/pubmed/19326054)