During bedside care, a nurse should know why the physician prescribed a specific type of IV fluid for a certain patient. So just in case something goes wrong while the patient is on IV therapy, the nurse would be able to apply the proper interventions.
Here’s an easy guide on how to fully understand and differentiate hypertonic, hypotonic, and isotonic solutions, with their corresponding nursing interventions.
What are IV Fluids?
As a recap, intravenous fluids or solutions are fluids administered via the intravenous route, when oral administration is not recommended.
Why are IV fluids administered?
- To maintain or restore fluid volume
- To replace electrolytes in the intravascular compartment
- To administer medications because it is the fastest way for medicines to work.
- For parenteral nutrition for feeding replacement
Iso- means” equal.” In other words, isotonic fluids have equal osmotic pressure inside and outside of a cell. The solutes have the same concentration as the blood plasma; that’s why it expands intracellular and extracellular compartments when it’s infused.
Remember the keyword “equal” when studying isotonic solutions. It has equal osmolality with the insides and outsides of the cell and has equal blood plasma concentration. As a result, it does not cause red blood cells to swell or shrink. It is indicated for patients who have hypovolemia.
Total concentration of solutes: 250 to 375 mEq/L
Isotonic IV Fluids:
- Normal Saline Solution / 0.9% NaCl
- D5 Water / Dextrose in 5% Water
- D5LRS / Dextrose in Water with 5% Lactated Ringer’s Solution
- Ringer’s Solution
Nursing Management when administering Isotonic Solutions:
- Assessment: Vital signs, signs of edema, auscultate heart, and lung sounds for any signs of fluid overload.
- Observe: Hypervolemia or fluid overload signs such as (bounding pulse, high blood pressure, respiratory crackles, shortness of breath, dyspnea, edema, jugular vein distention, extra heart sounds).
- Prevent hypervolemia: Patients who are prescribed with isotonic solutions have hypovolemia, which may lead to hypervolemia, when not monitored properly.
- Patient’s position: As a nurse, it is important to prevent hypervolemia with Semi-fowler’s position or elevate the head of the bed at a 35-45 degree angle. If a patient has peripheral edema, elevate the patient’s leg to promote venous return.
- Monitor: Hypovolemia or lack of fluid. Observe for signs and symptoms such as decreased urine output, tachycardia, poor skin turgor, weak pulse, and low blood pressure.
- Watch out for: Signs of swelling any difficulty of breathing. It must be reported immediately.
Hypo- means low which, in the case of IV fluids, has fewer solutes and has more fluid. This will cause the fluids to move inside the cell, resulting in the expansion or swelling of the cell.
Since the osmolality of hypotonic solutions is lower, the fluid from outside of the cell enters inside the cell to achieve homeostasis. This then may result in swelling, even the rupturing of cells. This is why it’s indicated to assist in excreting bodily wastes, to address cellular dehydration, and to replace the fluid inside the cell.
Total concentration of solutes: 250 mEq/L or less
Hypotonic IV Fluids:
- 0.45% NaCl / 0.45% Sodium Chloride
- 0.33% NaCl / 0.33% Sodium Chloride
- 0.225% NaCl / 0.225% Sodium Chloride
- 2.5% Dextrose in Water / D25W
Nursing Management when administering Hypotonic Solutions
- Assessment: Vital signs, edema, auscultation of heart, and lung sounds.
- Contraindications: Hypovolemia, hypotension, liver damage, increased intracranial pressure (ICP), burns, trauma, administration, and blood products.
- Watch out for: Signs of increased intracranial pressure because it may lead to cerebral edema. Monitor for signs and symptoms of fluid volume deficit such as confusion and dizziness. Also, look for signs of excessive infusion like hypotension, cellular damage, and cellular edema.
Hyper- means excess, meaning this type of solution has more solutes than fluid, which is the complete opposite of hypotonic solutions. Hypertonic solutions cause fluids to move out from inside of the cell to create homeostasis; this will cause the solutes to be normalized inside and outside the cell.
As the exact opposite of hypotonic solutions, hypertonic solutions cause the cell to shrink from the inside. This volume expander pulls out the fluid from the inside of the cell, increasing the extracellular fluid volume, and causing the cell to shrink.
Total concentration of solutes: 375 mEq/L
Hypertonic IV solutions:
- 10% Dextrose in Water (D10W)
- 20% Dextrose in Water (D20W)
- 50% Dextrose in Water (D50W)
Nursing Management when administering Hypertonic Solutions
- Assessment: Vital signs, edema, auscultate for heart and lung sounds.
- Watch out for: Hypervolemia or fluid overload, swelling in the face, arms, and legs, hypertension, difficulty of breathing, signs of hyperglycemia, and any discomfort in the body.
- Hyperglycemia: Since rapid infusion of hypertonic solutions may cause hyperglycemia, the nurse must monitor the patient’s glucose count. Patients with diabetes mellitus must be monitored accordingly.
- Verify the doctor’s order: The nurse is responsible for verifying the doctor’s order on which specific hypertonic IV fluid should be administered, the total volume, time to be consumed, and infusion rate.
- Contraindications: Heart disease, kidney damage, dehydrated patients.
- IV Route: Hypertonic solutions are administered through a central vein using a central vascular access device. Hypertonic solutions should not be administered peripherally because it can cause irritation and damage to the blood vessels.
Just remember that hypertonic solutions may cause the cell to shrink, while hypotonic solutions may cause the cell to swell and explode. When it comes to isotonic solutions, remember the keyword “equal,” meaning they have equal osmolality with the insides and outsides of the cell.
Knowing these concepts by heart helps you easily identify what nursing interventions to apply for certain cases. If you’ve also noticed, the nursing management for the three IV solutions is highly focused on avoiding fluid volume excess. Always look out for signs of edema and remember to take note of each fluid’s contraindications.