What Are Intravenous Solutions?

One of the primary interventions in a hospital setting is the intravenous administration of solutions. Nurses need to know the differences between the solutions, what each one is for and what to watch out for when administering them. Volume expanders administered IV come in two broad categories: crystalloids and colloids. The IV route can also be used to administer blood and blood products, parenteral nutrition (nutrition that bypasses the gastrointestinal system) and medications.

Crystalloid Solutions

• Crystalloid solutions contain molecules small enough to pass through the membranes of cells and various vascular spaces. This gives them the ability to help move fluids into and out of the intracellular spaces through different tonicities, such as isotonic, hypotonic and hypertonic solutions. The most common types of isotonic crystalloids are normal saline solution (a solution of 0.9 percent sodium chloride) and lactated Ringer's solution. They promote no fluid shift and replace electrolytes. Hypotonic solutions include half-normal saline (0.45 percent NaCl) solution and 5 percent dextrose in water. These solutions hydrate the cells and get fluid out of the vessels. The hypertonic solutions of 5 percent dextrose in half-normal saline solution or 5 percent dextrose in normal saline solution bring the fluid back into circulation. They can expand the vessels and also replace some electrolytes.

Colloid Solutions

• A colloid solution contains a complex colloidal protein unable to pass through the cell membranes into the vascular spaces. This causes fluids to move out of the intracellular spaces and into the blood vessels. Albumin is the most commonly used colloid. It is used to replace albumin when there is a lack but is also a volume expander. Dextran can also be used to expand the fluid in the vessels. Hetastarch, a synthetic starch, is another colloid used for expansion. Finally, mannitol is used to move fluid off of a patient who is not urinating frequently. Mannitol helps pull the fluid into the vessels so that it can be processed for urination and is also useful in brain swelling situations.

Blood Products

• Blood products such as platelets and plasma can be transfused into a patient via a IV line. Usually, just a component of blood is administered, such as red blood cells, to help a patient's medical condition. All blood products are screened for blood type and Rh antigen. Blood products can be administered for a variety of reasons such as anemia, blood loss, and clotting diseases. Transfusion reactions, although rare, can occur and can be life-threatening if not caught in time.

Parenteral Nutrition

• Parenteral nutrition is nutrition administered via IV access. Although it is possible to give total parenteral nutrition through an IV inserted peripherally, it is not recommended. Most TPN must be administered through a central catheter or a peripherally inserted central catheter. This form of nutrition is generally reserved for patients who have a bowel blockage or some other reason for not using the gastrointestinal system. There are many complications associated with TPN, such as sepsis related to the IV site, liver dysfunction and glycemic abnormalities. For this reason, TPN is used with caution.

Medications

• Medications of all kinds can be given through the IV route. They can be added to a crystalloid solution and infused over an allotted period of time. Medications can also be infused at a slow drip so that the patient gets only a specified amount of the medication at a time. Finally, a nurse can push a syringe of medication directly into a patient's vein to elicit an immediate therapeutic response. Antibiotics, pain medications and anesthesia are a few of the types of medications that can be administered through an IV.