Pharmacology · chapter 5 · Fluids and Electrolytes, Vitamins, Minerals, and Alternative Therapies
Fluid Volume
The 14 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.
Key points
What fluid volume means
Fluid Volume Introduction Fluid volume refers to the total amount of fluid present in the body, which includes both intracellular (inside cells) and extracellular (outside cells) fluids.
The body is mostly water
The body is composed of approximately 60 percent water, which is distributed throughout the body in various compartments, including blood vessels, tissues, and organs.
What a fluid imbalance is
An abnormal distribution of fluids between the ICF and ECF compartments can disrupt cellular function and result in fluid imbalance in the form of either a deficit or an excess (Brinkman et al., 2023).
Causes of fluid imbalance
A fluid imbalance can be caused by a variety of factors including medical conditions, such as kidney and heart disease, medication use, and lifestyle factors, such as diet and exercise.
Treating the imbalance
Treatment for the imbalance typically involves addressing the underlying cause and restoring the balance of fluids and electrolytes in the body. This may include oral or intravenous fluids, electrolyte replacement, and other interventions as necessary.
Why hypovolemia develops
This can be due to a loss of sodium from the body, decreased fluid intake, or a combination of both. Several conditions and diseases can lead to fluid volume deficit, such as dehydration, diabetes insipidus, and hemorrhage.
Drugs that can cause hypovolemia
Certain drugs, including diuretics, blood pressure drugs (e.g., angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), which inhibit aldosterone), and laxatives (which increase fluid loss through stools), can lead to hypovolemia (Melendez-Rivera Anjum, 2022).
Treating fluid volume deficit
Treatment of fluid volume deficit involves replenishing fluids and electrolytes through oral rehydration therapy or intravenous (IV) fluid replacement, depending on the severity of the deficit.
Why hypervolemia develops
This can be due to increased fluid intake, decreased fluid output, or a combination of both. Several conditions and diseases can lead to fluid volume excess, including heart failure, liver disease, and kidney disease (Ekinci et al., 2018).
Drugs that cause fluid retention
Certain drugs such as nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids (which can lead to fluid retention by affecting the kidneys’ ability to eliminate sodium and water), hormonal therapies such as estrogen replacement (which can lead to fluid retention), and diabetes drugs such as thiazolidinediones can cause fluid retention as an adverse effect.
Treating hypervolemia
Treatment of hypervolemia involves addressing the underlying cause, restricting fluid and sodium intake, and increasing urine output through diuretic drugs.
Fluid replacement is closely monitored
Fluid volume replacement is administered by health care professionals, and the treatment is closely monitored to ensure that the client’s fluid and electrolyte levels are being properly balanced.
Blood products used for replacement
The most commonly used forms of blood products for fluid replacement are packed red blood cells (PRBCs), platelets, plasma, and cryoprecipitated anti-hemophilic factor (cryo) (American Red Cross, n.d.)
Why blood products are given
Blood and blood products are administered intravenously to replenish lost fluids/blood, maintain the body’s blood pressure and hormonal balance, and restore the body’s oxygen-carrying capacity (Lotterman Sharma, 2022).
Terms to know
- Fluid volume deficit
- Fluid Volume Deficit Fluid volume deficit, also known as hypovolemia, is a condition that occurs when there is a decrease in the body’s fluid volume.
- Fluid volume excess
- Fluid Volume Excess Fluid volume excess, also known as hypervolemia, is a condition that occurs when there is an abnormal increase in the body’s total fluid volume.
- Electrolytes
- Electrolytes are electrically charged minerals such as sodium, potassium, chloride, phosphate, magnesium, and calcium, which play roles in regulating cellular function and maintaining the body’s fluid balance (Melendez-Rivera Anjum, 2022).
- Fluid volume replacement
- Fluid Replacement Fluid volume replacement is a medical treatment that involves replenishing lost fluid and electrolytes, specifically sodium in the body, typically through IV infusion.
Practice questions
Stuck on select-all-that-apply? How to take them one option at a time.
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Every question here, with the answer
A client who has been taking a diuretic and a laxative at home reports dizziness when standing up. The nurse notes a fast heart rate and a drop in blood pressure on standing. Which imbalance does the nurse suspect?
- Fluid shift into the lungs
- Normal fluid balance with anxiety
- Fluid volume deficit
- Fluid volume excess
Answer: Fluid volume deficit
Diuretics and laxatives can lead to hypovolemia, and postural dizziness, postural hypotension and tachycardia are manifestations of fluid volume deficit. Fluid volume excess shows as swelling, crackles, weight gain and high blood pressure instead.
A client with heart failure is admitted with fluid volume excess. Which findings would the nurse expect? Select all that apply.
- Swelling in the ankles and feet
- Crackles in the lungs
- Weight gain
- Shortness of breath
- Postural hypotension
Answer: Swelling in the ankles and feet, Crackles in the lungs, Weight gain, Shortness of breath
Shortness of breath, crackles, swelling of the legs, ankles and feet, weight gain and high blood pressure are listed manifestations of fluid volume excess. Postural hypotension belongs to fluid volume deficit.
A client with hypervolemia from kidney disease asks what the treatment will involve. Which answer by the nurse is accurate?
- Receiving an IV fluid bolus
- Increasing salt in the diet
- Limiting fluid and sodium and taking a diuretic to increase urine output
- Drinking extra fluids to flush the kidneys
Answer: Limiting fluid and sodium and taking a diuretic to increase urine output
Hypervolemia is treated by addressing the cause, restricting fluid and sodium intake, and increasing urine output with diuretics. Extra fluids, an IV bolus or more salt would add to the excess.
A nurse reviews the home medications of a client who has developed swelling in both legs. Which medication could be contributing to fluid retention?
- An ACE inhibitor
- A nonsteroidal anti-inflammatory drug (NSAID)
- A loop diuretic
- A laxative
Answer: A nonsteroidal anti-inflammatory drug (NSAID)
NSAIDs and corticosteroids can cause fluid retention by affecting the kidneys' ability to eliminate sodium and water. Laxatives, diuretics and ACE inhibitors are listed as drugs that can lead to hypovolemia, not retention.
A client is admitted after a severe hemorrhage. Which are purposes of giving blood and blood products to this client? Select all that apply.
- Increase urine output through diuresis
- Maintain blood pressure
- Prevent shock
- Replenish lost fluids and blood
- Restore oxygen-carrying capacity
Answer: Maintain blood pressure, Prevent shock, Replenish lost fluids and blood, Restore oxygen-carrying capacity
After severe blood loss, replacement restores blood volume and prevents shock, and blood products replenish lost blood, maintain blood pressure and restore oxygen-carrying capacity. Increasing urine output is the goal of diuretics in hypervolemia.
A nursing student asks what fluid volume deficit usually results from. Which response is accurate?
- Loss of sodium, decreased fluid intake, or both
- Increased fluid intake
- Heart failure and liver disease
- Decreased fluid output
Answer: Loss of sodium, decreased fluid intake, or both
Fluid volume deficit can be due to loss of sodium, decreased fluid intake, or both. Increased intake, decreased output, heart failure and liver disease are causes of fluid volume excess.
Where every quote comes from
Section 5.1 Fluid Volume of Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver, OpenStax, 2024. Read the whole section free at openstax.org.
The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.