IV fluid restores fluid to the intravascular compartment, and some IV fluids are also used to facilitate the movement of fluid between compartments due to osmosis. There are three types of IV fluids: isotonic, hypotonic, and hypertonic.
Isotonic solutions are IV fluids that have a similar concentration of dissolved particles as blood. An example of an isotonic IV solution is 0. Because the concentration of the IV fluid is similar to the blood, the fluid stays in the intravascular space and osmosis does not cause fluid movement between compartments. See Figure Isotonic solutions are used for patients with fluid volume deficit also called hypovolemia to raise their blood pressure. However, infusion of too much isotonic fluid can cause excessive fluid volume also referred to as hypervolemia.
Hypotonic solutions have a lower concentration of dissolved solutes than blood. An example of a hypotonic IV solution is 0. When hypotonic IV solutions are infused, it results in a decreased concentration of dissolved solutes in the blood as compared to the intracellular space.
This imbalance causes osmotic movement of water from the intravascular compartment into the intracellular space. For this reason, hypotonic fluids are used to treat cellular dehydration.
However, if too much fluid moves out of the intravascular compartment into cells, cerebral edema can occur. If a patient has diabetic ketoacidosis, their bloodstream is going to be overfilled with ketones and glucose, making it relatively hypertonic compared to normal blood. Starting to see a pattern here? The red blood cells in particular are concerning, because they are basically swimming in a hypertonic solution… and you only have to take one look at what happens to an egg placed in hypertonic solution to see that it is not a good situation!
Just like the egg, water will soon start exiting the red blood cells. Without any intervention, they will become severely dehydrated and likely start dying.
In order to correct this imbalance, we might choose to administer a hypotonic IV solution with the intention of diluting the bloodstream and ultimately driving the water back into the red blood cells. This will cause water to start moving back into the red blood cells via osmosis. Typically, if a patient needs a hypotonic solution then they will receive 0.
In nursing school and on the NCLEX exam , you will be required to know what type of IV fluids are considered isotonic, hypotonic, and hypertonic. In this article, I give you an easy overview of each solution and how they work on the cellular level. In addition, I have an isotonic, hypotonic, and hypertonic quiz you can take to test your knowledge on this content.
Each part is made up of a solution and depending on the tonicity of the fluid you can having shifting of fluids from outside of the cell to the inside via osmosis. The cell loves to be in an isotonic state and when something happens to make it unequal like with hypotonic or hypertonic conditions it will use osmosis to try to equal it out.
That's why isotonic solutions such as 0. Because these solutions expand the intravascular compartment, closely monitor the patient for signs and symptoms of fluid overload, especially if he has a history of hypertension or heart failure. Although D 5 W is isotonic in the bag, it acts like a hypotonic solution once it enters the bloodstream because simple sugars such as dextrose are the preferred energy source for cells.
The low concentration of dextrose in D 5 W is quickly consumed by the cells lining the vein and circulating in the bloodstream. Use this solution with caution in patients at risk for increased intracranial pressure ICP. The liver converts lactate to bicarbonate, so don't give lactated Ringer's solution if the patient has a serum blood pH above 7.
Potassium chloride may be added in low concentrations to replace losses from the gastrointestinal system. When a hypotonic solution is administered, it puts more water in the serum than is found inside cells.
As a result, water moves into the cells, causing them to swell. Although hypotonic solutions help replace intracellular fluid, the extra water also moves into the cells of the tunica intima of the vein at the catheter insertion site. This may cause the cells to swell and burst, exposing the vein's basement membrane and potentially leading to phlebitis and infiltration.
Watch all I. Because hypotonic solutions have the potential to cause sudden fluid shifts from blood vessels into cells, don't administer them indefinitely. Stop infusing a hypotonic solution once the patient can drink enough to meet his fluid needs.
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