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Intravenous solutions

Intravenous (IV) fluids are infused to maintain fluid balance, replace fluid losses, and treat electrolyte imbalances. They are commonly available in volumes ranging from 25 mL to 1,000 mL and are dispensed in either plastic bags or glass bottles.

Glass bottles are used primarily for infusing substances that are unstable in plastic bags. For fluids to flow out of a glass bottle, there must be a mechanism that allows air to enter the bottle. This is usually accomplished by incorporating a vent into the drip chamber of the tubing. In most healthcare facilities today, IV solutions are supplied in plastic bags. Because the bag collapses as the fluid infuses, no air vent is required for the fluid to flow out of the bag.

IV fluids are commonly organized into three general categories: isotonic, hypotonic, and hypertonic. Providers typically order a solution based on the particular patient’s serum electrolyte values and fluid-volume balance. All IV fluids must be administered carefully, but hypertonic solutions are particularly risky. These solutions pull fluid into the vascular space by osmosis, resulting in an increased vascular volume that can result in pulmonary edema, particularly in patients who have cardiac or renal disease.

Isotonic solutions have an approximate electrolyte content of 300 mEq/L. This type of solution is infused to replace fluid losses, usually extracellular losses, and to expand the intravascular volume. Most isotonic solutions do not provide calories or free water. Examples of isotonic solutions are 0.9% sodium chloride, commonly called normal saline (NS), and lactated Ringer’s (LR).

Hypotonic solutions have an electrolyte content of less than 250 mEq/L and are administered to expand the intracellular space. They are commonly infused to dilute extracellular fluid and rehydrate the cells of patients who have hypertonic fluid imbalances and to treat gastric fluid loss and dehydration from excessive diuresis. This type of solution provides free water, sodium, and chloride but does not provide calories or other electrolytes. An example of a hypotonic solution is 0.45% sodium chloride (0.45% NS), commonly called half normal saline.

Solutions with an electrolyte content of 375 mEq/L or more are considered hypertonic. Hypertonic solutions are infused to treat patients who have severe hyponatremia. Depending on the type of hypertonic fluid infused, it can provide patients with calories, free water, and some electrolytes. Examples of hypertonic solutions are dextrose 10% in water (D10W) and dextrose 5% in 0.9% sodium chloride (D5NS).

Because hypertonic solutions can be extremely irritating to the patient’s veins, some must only be infused through a central line. Before initiating a hypertonic solution, be sure to check your facility’s policy to determine the appropriate intravenous route.

Additives such as vitamins and electrolytes are often infused along with an IV solution. Most IV fluids are manufactured with the additives already included to avoid contamination of the fluid and to prevent errors. If an IV solution is not available with the prescribed additives already included, they should be added in the pharmacy department under a laminar flow hood.

Because the names of IV solutions are often abbreviated or shortened, it is important to become familiar with the names of the different solutions. If you are uncertain about a solution, consult an intravenous therapy drug guide or a pharmacist before initiating the infusion.


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