IV Fluids

Isotonic Solutions:

• 0.9% Saline (aka Normal Saline)
• Normal Saline is given to increase the amount of fluid in the blood vessels (intravascular space), without significantly changing the balance of electrolytes in the body.  This is useful for making sure a patient remains in a well-hydrated state of homeostasis.  Normal Saline also happens to be the only IV solution that can be infused at the same time as a blood product.
• Use to expand volume, dilute medications, and to keep vein open.
• Ringer’s Solution
• Lactated Ringers
• Ringer’s and Lactated Ringer’s Solutions contain a wider variety of electrolytes than Normal Saline, which makes them even more similar to what’s found in blood plasma.
• Use for fluid resuscitation
• 5% Dextrose in 0.225% Saline
• 5% Dextrose in Water (D5W) 
• The Isotonic Dextrose solutions have the same goal as the hypertonic dextrose solutions; to provide extra calories to the patient. Dextrose is just a sugar, which can be easily absorbed by the body and turned into energy.
• 5% Dextrose in Water is a special case. Although it is technically isotonic, it acts upon the body as if it is hypotonic as glucose is metabolized.

Hypotonic Solutions: contain less solute than blood, which causes water to want to leave the hypotonic solution and enter an area that has a higher concentration of solute via osmosis.  When discussing IV fluids, that usually means that the water will want to leave the intravascular space and enter Red Blood Cells (RBCs).

• 0.45% Saline
• the most common reason to give 0.45% Saline is for true dehydration, which is when the body has lost water, without losing any electrolytes (this is different from fluid volume deficit, when the body loses BOTH water AND electrolytes).  In dehydration, the body already has a normal amount of electrolytes, so there is no need to provide more in the IV solution.  The patient simply needs some of their water replaced!
• *5% Dextrose in Water 
• this is technically isotonic, but once the dextrose is absorbed then it acts on the body as if it was hypotonic

Hypertonic Solutions: has a higher solute to solvent ratio than blood does. Blood basically becomes our definition of what “Isotonic” means. Useful for a patient who needs electrolytes but is already on fluid overload, such as in Heart Failure or severe edema.  That way you are providing the patient with needed electrolytes, but minimizing the extra water that their condition doesn’t get worse.

• 3% Saline
• typically used to treat severe cases of hyponatremia (low sodium).  This makes sense because if your blood stream has become hypotonic and it’s supposed to be isotonic, then adding a hypertonic solution will help increase the electrolyte imbalance back to normal levels. 
• Caution: You need to infuse the IV solution very slowly and cautiously, and watch the patient closely for any evidence of intravascular overload (too much fluid in the blood vessels).  This could be increased blood pressure, pulmonary edema (fluid in the lungs), or even hypernatremia (high sodium).
• 10% Dextrose in Water
• 5% Dextrose in 0.45% Saline
• 5% Dextrose in 0.9% Saline
• These three dextrose solutions are primarily used for the purpose of providing the patient with extra calories.