Hypertonic Hypotonic Isotonic Solutions

Last updated on May 18th, 2022 at 08:55 am

Isotonic Hypotonic and Hypertonic Solutions Examples

IV Fluids Nursing Study Guide: Isotonic, Hypertonic, and Hypotonic Solutions

Water is necessary to every cell in our bodies, as our bodies are made up of about 60% water. IV fluids may be required when a person does not have enough fluids in their body.

Intravenous fluids, commonly referred to as intravenous solutions, are additional fluids used in intravenous therapy to restore or maintain adequate fluid volume and electrolyte balance when oral administration is not an option.

Intravenous fluid therapy is a convenient and simple method to administer fluids, replace electrolytes, and administer drugs and blood products straight to the intravascular fluid compartment.

Types of IV Fluids

Intravenous fluids come in a variety of forms and are classified in a variety of ways. Depending on why a patient needs them, the healthcare provider will choose which type is best for them.

When it comes to IV fluids and cells inside the body, osmosis and osmotic pressure are significant players. Osmosis, a process that regulates water and electrolytes so that their distribution and composition in the compartments stay balanced, transports fluid between them. 

Depending on the treatment goal, IV fluids are specifically tailored to elicit a certain reaction in the cells through osmosis.

A. Crystalloids

Micro molecules in crystalloid IV solutions move quickly over semipermeable membranes. According to their relative tonicity relative to plasma, they are divided into three categories.

1. Isotonic Solutions

Most IV fluids are isotonic, which means that the solute and solvent concentrations/ratios are the same. The following is a list of IV fluids and their indications that fall under this category.

• Normal saline solution (0.9% NaCl) or NSS. The percentage of sodium chloride dissolved in the solution is similar to the normal concentration of sodium and chloride in the intravascular space, which is why it is termed normal saline solution.

Indications: Normal saline is the preferred isotonic solution for expanding the extracellular fluid (ECF) volume. It is also the IV fluid being used together with blood products and also used to replenish huge amounts of sodium lost from burns and trauma.

It should never be infused if the patient has heart failure, pulmonary edema, renal impairment, or any other condition that causes sodium retention since it may result in fluid volume overload.

• D5W (dextrose 5% in water). D5W is initially an isotonic solution that provides free water for the kidneys and when dextrose is absorbed, the residual water and electrolytes make an isotonic solution. A liter of this IV fluid contains less than 200 kcal and 50 grams of glucose.

Indications: It is given to those who have low sugar levels in the blood (hypoglycemia), insulin shock, hypernatremia, or dehydration (fluid loss). It should never be used for fluid resuscitation as it may result in hyperglycemia. It should also be avoided to be used in patients at risk for or with increased intracranial pressure as cerebral edema may develop.

• Lactated Ringer’s 5% Dextrose in Water (D5LRS). Electrolytes such as sodium, potassium, calcium, and chloride are present in D5LRs, also known as Ringer’s Lactate or Hartmann solution. It also contains bicarbonate precursors to prevent acidosis, but it lacks calories and magnesium, and it only replaces a little amount of potassium. Because its electrolyte composition is closely related to the chemistry of the body’s blood serum and plasma, it is the most biologically responsive fluid.

Indications: Lactated Ringer’s is used to treat dehydration, sodium deficiency, and fluid loss in the gastrointestinal tract. It is also used to treat fluid loss from burns, fistula drainage, and injuries. It is the primary option for some patients that needs fluid resuscitation and is frequently used to manage metabolic acidosis. Lactated Ringer’s is converted to bicarbonate in the liver, hence it should not be given to patients who are unable to metabolize lactate, such as those with liver illness or lactic acidosis. Patients suffering from cardiovascular or kidney failure should use it with caution.

• Ringer’s Solution. Ringer’s solution is an isotonic IV solution with a similar composition to Lactated Ringer’s Solution but without the lactate.

Indications: Lactated Ringer’s has the same indications as Lactated Ringer’s but without the lactate contraindications.

Nursing Considerations When Using Isotonic Solutions

When giving isotonic IV fluids, these are the general nursing interventions and considerations:

• Keep a record of the patient’s baseline data. Examine the patient’s vital signs, characteristics of edema, lung sounds, and heart sounds before starting the infusion. Continue to monitor the patient during and after the infusion.
• Watch out for indicators of fluid overload. Elevated blood pressure, irregular pulse, pulmonary crackles, difficulty and shortness of breath, peripheral edema, distended neck veins, and unusual heart sounds are all indications of fluid overload or hypervolemia.
• Continuous monitoring of persistent hypovolemia. Reduced urine production, poor skin turgor, tachycardia, a weak pulse, and low blood pressure are all signs of persistent hypovolemia.
• Avoid incidence of fluid overload. Following a sudden or excessive infusion of isotonic IV fluids, patients being managed for hypovolemia can rapidly develop fluid overload.
• Raise the head of the bed at a 35 to a 45-degree angle. Place the client in a semi-Fowler’s position except if contraindicated.
• Raise the legs of the patient. Elevate the patient’s legs if edema is evident to encourage venous return.
• Teach the patients and their families. Educate patients and their families on how to identify the signs and symptoms of hypervolemia. Instruct patients to contact their nurse if they experience any difficulty breathing or observe any edema.
• Closely monitor patients with heart failure. Patients with hypertension and heart failure should be thoroughly assessed for indications of hypervolemia as isotonic solutions expand the intravascular space.

2. Hypotonic Solutions

If the total electrolyte concentration of an IV solution is less than 250 mEq/L, it is considered hypotonic. To establish homeostasis, they cause fluid to transfer from the ECF to the ICF, causing cells to expand and possibly rupture. Hypotonic IV fluids are typically used to replace cellular fluid, give free water for the elimination of bodily wastes, and address cellular dehydration.

• 0.45% Sodium Chloride (0.45% NaCl). The hypotonic IV solution sodium chloride 0.45%, sometimes called half-strength normal saline, is used to replace the water in patients with hypovolemia and hypernatremia. Excessive use of these solutions can cause hyponatremia, especially in people who are susceptible to water retention.

• 0.33% Sodium Chloride Solution (0.33% NaCl). 0.33% NaCl IV fluids are administered to help the kidneys to maintain the necessary amounts of water, and they’re usually paired with dextrose to improve tonicity. Patients with heart failure or renal dysfunction should use it with caution.

• 0.225% Sodium Chloride Solution (0.225% NaCl). Because it is the most hypotonic IV fluid known, it is frequently used as a maintenance solution for pediatric patients. It can also be used with dextrose.

• 2.5% Dextrose in Water (D2.5W). This solution is being used to manage dehydration and lower sodium and potassium levels. It should not be given with blood products since it can cause red blood cell hemolysis.

Nursing Considerations When Using Hypotonic Solutions

When giving hypotonic IV fluids, these are the general nursing interventions and considerations:

• Keep a record of the patient’s baseline data. Examine the patient’s vital signs, characteristics of edema, lung sounds, and heart sounds before starting the infusion. Continue to monitor the patient during and after the infusion.
• Do not use them if there are any contraindications to the patient. Hypotonic solutions can aggravate hypovolemia and hypotension, resulting in cardiovascular collapse. Patients with liver disease, injuries, or burns should not use this type of IV fluid.
• Watch out for the possibility of increased intracranial pressure is a possibility (ICP). It should never be given to patients who are at risk of developing ICP because the movement of fluid could result in cerebral edema.
• Watch out for signs of a fluid volume deficiency. In older individuals, confusion is one of the signs and symptoms. Instruct patients to notify the nurse if they become lightheaded.
• Avoid infusing excessively. Intravascular fluid deficiency, hypotension, cellular swelling, and cell injury can all result from an excessive administration of hypotonic IV fluids.
• Never use hypotonic solutions in combination with blood products. The majority of hypotonic solutions can induce hemolysis in red blood cells, mainly when the IV fluid is infused rapidly.

3. Hypertonic Solutions

Hypertonic solutions contain more solutes than plasma and drive fluids to flow out of cells and into the ECF in order to balance particle concentrations between the two compartments. Cells shrink as a result of this action, which may compromise their function. They are also known as volume expanders since they pull water out of the intracellular space, increasing the levels of extracellular fluid.

a. Hypertonic Sodium Chloride IV Fluids. The sodium and chloride concentrations in hypertonic sodium chloride solutions are higher than those found in plasma. Fluids are shifted from the intracellular space to the intravascular and interstitial spaces when a hypertonic sodium chloride solution is administered. These IV solutions come in 3% sodium chloride (3% NaCl) and 5% sodium chloride (5% NaCl).

Indications: They are used to treat acute sodium deficiency and should only be used to treat hyponatremia in life-threatening situations. These are also administered as part of diuretic therapy in patients with cerebral edema.

b. Hypertonic Dextrose Solutions. Isotonic solutions containing 5% dextrose, such as D5NSS and D5LRS, are somewhat hypertonic as their total osmolality exceeds that of the ECF. Dextrose, on the other hand, is quickly absorbed and only the isotonic solution remains, therefore its effect on the ICF is only transient. In the short term, hypertonic dextrose solutions are known to give kilocalories to the patient.

c. Dextrose 10% in Water (D10W). This IV fluid is a hypertonic IV solution that delivers calories, free water, and no electrolytes and is used to treat ketosis from starvation. If necessary, it should be infused through a central line; however, it should not be administered through the same line as blood products because it can elicit RBC hemolysis.

d. Dextrose 20% in Water (D20W). This hypertonic IV solution is an osmotic diuretic that promotes diuresis by causing fluid changes between compartments.

e. Dextrose 50% in Water (D50W). This hypertonic IV solution is widely used to treat severe hypoglycemia and is given as a bolus through the IV.

Nursing Considerations When Using Hypertonic Solutions

When giving hypertonic IV fluids, these are the general nursing interventions and considerations:

• Keep a record of the patient’s baseline data. Examine the patient’s vital signs, characteristics of edema, lung sounds, and heart sounds before starting the infusion. Continue to monitor the patient during and after the infusion.
• Watch out for indicators of fluid volume overload. Hypertonic solutions raise the extracellular fluid volume and increase the risk of hypervolemia by moving fluid from the ICF to the ECF. Monitor for swelling in the arms, legs, and face, as well as shortness of breath, hypertension, and bodily discomforts such as headache and cramping.
• Closely observe the patient during administration. Hypertonic solutions should only be used in high-acuity locations, with nurses on hand to monitor for possible repercussions.
• Always confirm the doctor’s order. The exact hypertonic fluid to be infused, the total volume to be infused, the infusion rate and the duration of the infusion should all be specified in the prescription for hypertonic solutions.
• Evaluate the patient’s medical history. Hypertonic IV fluids should not be given to patients who have kidney or cardiac disorders, or who are dehydrated. Patients with renal or cardiac problems may experience fluid volume overload as a result of these solutions, which might compromise renal filtration processes.
• Prevent fluid volume overload at all costs. Make sure that hypertonic fluid infusion does not result in fluid volume excess or overload.
• Do not infuse the solution in peripheral sites. Hypertonic solutions should be delivered through a central vascular access device put into a central vein since they can cause irritation and damage to the blood vessel.
• ●       Watch out for the blood glucose levels of the patient. Hyperglycemia can be caused by a rapid infusion of hypertonic dextrose solutions. These solutions should be used with caution with diabetic patients.

Colloids

Colloids are intravenous fluids containing high-molecular-weight solutes; technically, they are hypertonic solutions that, when infused, induce an osmotic pull on fluids from the interstitial and extracellular spaces. Large molecules in colloids cannot pass through semipermeable membranes. They are beneficial for increasing blood pressure and expanding intravascular volume. Colloids are recommended for patients who are malnourished or who are unable to sustain massive fluid infusions.

• Human Albumin

Human albuminis a plasma-derived solution that comes in two concentrations: 5% albumin and 25% albumin. 5% albumin is a typical colloid solution used to enhance blood volume and replenish protein levels in cases like burns, pancreatitis, and trauma-induced plasma loss. In contrast, 25% albumin is utilized in conjunction with sodium and water limitation to reduce excessive edema. Albumin is administered using similar guidelines and nursing considerations as other blood transfusion products. It is not prescribed to patients with severe anemia, heart failure, or known albumin sensitivity. Because of the risk of hypotension and flushing, angiotensin-converting enzyme inhibitors should be avoided for at least 24 hours before infusing albumin.

• Dextrans

Dextrans comes in two forms: low-molecular-weight dextrans (LMWD) and high-molecular-weight dextrans (HMWD), both of which are polysaccharides that function as colloids. If blood cross-matching is expected, draw the patient’s blood first before administering dextran as it may interfere with the cross-matching result.

1. LMWDs do not have any electrolytes in them and are used to treat shock caused by burns, hemorrhage, trauma, or surgery. They are used to prevent venous thromboembolism in some surgical procedures. They are not recommended for patients with thrombocytopenia, hypofibrinogenemia, or dextran hypersensitivity.
2. HMWD is used to treat hypovolemia and hypotension in patients. They are, however, contraindicated in patients suffering from hemorrhagic shock.

• Etherified Starch

These starch-based solutions are used to enhance intravascular fluid levels; however, they can affect the body’s natural coagulation. EloHAES, HyperHAES, and Voluven are examples of these solutions.

• Gelatin

A gelatin solution has a lower molecular weight than dextrans, therefore it stays in the bloodstream for a lesser duration.

• Plasma Protein Fraction (PPF)

PPFsare a plasma-derived solution that, like albumin, is heated before administration. To boost the circulating volume, it’s best to infuse gradually.

Nursing Considerations When Using Colloid Solutions

When giving Colloid Solutions, these are the general nursing interventions and considerations:

• Check the patient’s history of allergy. Although rare, most colloids can induce allergic reactions, so get a thorough allergy history and inquire if they have ever had an adverse reaction to an IV infusion.
• Use an 18-gauge needle. When giving colloid solutions, a bigger needle is necessary.
• Keep a record of the patient’s baseline data. Examine the patient’s vital signs, characteristics of edema, lung sounds, and heart sounds before starting the infusion. Continue to monitor the patient during and after the infusion.
• Closely monitor the patient’s reaction. Constant monitoring of intake and output must be done to recognize signs of fluid volume overload, hypertension, shortness of breath, abnormal breath sounds like crackles, and swelling.
• Keep an eye on the coagulation indexes. Colloid solutions can impair platelet function and lengthen bleeding durations; thus, coagulation indexes must be carefully monitored.

Patient Scenarios

Most of the time, when administering IV fluids to patients, the tonicity, or measurement of osmotic pressure between two solutions that are opposing their health status, is provided. For example, the blood of a dehydrated patient is hypertonic, so a hypotonic solution will be most likely ordered to restore the tonicity to normal limits.

For some nurses, the topic of IV fluids is a challenging one. To better comprehend this topic, here are some of the patient scenarios that nurses may encounter, as well as the most common IV fluids to use and their rationale.

Scenario 1: A 38-year-old patient was brought to the emergency department after suffering from nausea, vomiting, and loose bowel movements for three days. The patient is dehydrated, but all electrolytes are within normal limits, according to the blood test.

The type of solution the patient’s blood has: Hypertonic

What type of IV fluid would the physician most likely prescribe for this patient?

• To expand their volume and give them more to move or shift around, an isotonic solution like 0.9% NaCl or Normal Saline may be used at first.
• To move the fluid into the cells, the next IV fluid will be a hypotonic solution, usually 0.45% NaCl is used.

Scenario 2: In the cardiology unit, a nurse is caring for a 63-year-old male patient who has +3 pitting edema on both lower extremities. The patient’s blood test reveals that he has congestive heart failure (CHF).

The type of solution the patient’s blood has: Hypotonic

What type of IV fluid would the physician most likely prescribe for this patient?

• For the fluid to transfer out of the extracellular space and into the vein, where it will be filtered out by the kidneys, a hypertonic solution will be the best option.

Scenario 3: The nurse receives a patient with low blood pressure, a frail appearance, and complains of dizziness and abdominal pain during the endorsement process. The blood test reveals that the patient has adrenal insufficiency.

The type of solution the patient’s blood has: Isotonic

What type of IV fluid would the physician most likely prescribe for this patient?

• Adrenal insufficiency results in loss of volume and sodium, causing hypovolemia and hyponatremic conditions. Isotonic solutions will most likely be used to treat the patient’s hypotension by increasing the volume of fluid in the veins.

Conclusion

When giving IV fluids, the type and amount of fluid administered can have an impact on the patient’s condition, thus nurses must be aware of the distinctions between fluid products and their implications.

Crystalloid solutions, which contain small molecules that flow easily across semipermeable membranes from the bloodstream into cells and body tissues, or Colloid solutions, which contain large molecules that do not pass through semipermeable membranes and thus remain in the blood vessels, are two types of fluid solutions.

Crystalloid solutions can be classified as isotonic, hypotonic, or hypertonic depending on their relative tonicity. To promote patient safety and a better outcome, nurses should become familiar with the nursing considerations for each type of intravenous fluids.

Nursing References

Ackley, B. J., Ladwig, G. B., Makic, M. B., Martinez-Kratz, M. R., & Zanotti, M. (2020). Nursing diagnoses handbook: An evidence-based guide to planning care. St. Louis, MO: Elsevier.  Buy on Amazon

Gulanick, M., & Myers, J. L. (2022). Nursing care plans: Diagnoses, interventions, & outcomes. St. Louis, MO: Elsevier. Buy on Amazon

Ignatavicius, D. D., Workman, M. L., Rebar, C. R., & Heimgartner, N. M. (2018). Medical-surgical nursing: Concepts for interprofessional collaborative care. St. Louis, MO: Elsevier.  Buy on Amazon

Silvestri, L. A. (2020). Saunders comprehensive review for the NCLEX-RN examination. St. Louis, MO: Elsevier.  Buy on Amazon

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