Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

26. Fluid and Electrolyte Balance, Acid Base Balance

Acid-Base Balance

Anatomy & Physiology

26. Fluid and Electrolyte Balance, Acid Base Balance

Acid-Base Balance

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Problem L3.1

Textbook Question

Elise Anderson is a 6-year-old girl who presents to the emergency department with a history of vomiting for the past 3 days. The nurse notices that her respiratory rate is abnormally low. What is the likely reason for this change in ventilation? Predict what Elise's arterial blood gas values would show.

Verified step by step guidance

Understand the physiological context: Vomiting for 3 days can lead to a significant loss of stomach acid (hydrochloric acid, HCl), which contains hydrogen ions (H⁺). This loss can result in a condition called metabolic alkalosis, where the blood becomes more alkaline (higher pH).

Relate metabolic alkalosis to respiratory compensation: The body attempts to compensate for metabolic alkalosis by reducing the respiratory rate. This hypoventilation leads to an increase in carbon dioxide (CO₂) levels in the blood, which helps lower the pH back toward normal by forming more carbonic acid (H₂CO₃).

Predict arterial blood gas (ABG) values: In metabolic alkalosis, you would expect the following changes: (1) Elevated blood pH (greater than 7.45), (2) Decreased hydrogen ion concentration ([H⁺]), (3) Elevated bicarbonate (HCO₃⁻) levels due to the alkalosis, and (4) Elevated partial pressure of carbon dioxide (PaCO₂) as a result of hypoventilation.

Explain the link between low respiratory rate and ABG values: The low respiratory rate observed in Elise is the body's compensatory mechanism to retain CO₂. This retention increases PaCO₂, which helps counteract the alkalosis by shifting the bicarbonate buffer system equilibrium toward producing more H⁺ ions: \( \text{CO}_2 + \text{H}_2\text{O} \leftrightarrow \text{H}_2\text{CO}_3 \leftrightarrow \text{H}^+ + \text{HCO}_3^- \).

Summarize the likely findings: Elise's ABG values would likely show a high pH (alkalosis), high bicarbonate (HCO₃⁻), and high PaCO₂ due to respiratory compensation. These findings are consistent with metabolic alkalosis and the body's attempt to restore acid-base balance.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Respiratory Rate and Ventilation

Respiratory rate refers to the number of breaths taken per minute and is a critical indicator of respiratory function. In children, a low respiratory rate can indicate hypoventilation, where the body is not expelling enough carbon dioxide (CO2). This can lead to respiratory acidosis, where the blood becomes more acidic due to increased CO2 levels.

Arterial Blood Gas (ABG) Analysis

Arterial blood gas analysis measures the levels of oxygen (O2), carbon dioxide (CO2), and the pH of the blood. It helps assess respiratory and metabolic function. In cases of hypoventilation, ABG values typically show elevated CO2 (hypercapnia) and decreased pH (acidosis), indicating respiratory failure or distress.

Causes of Vomiting and Its Effects

Vomiting can lead to dehydration and electrolyte imbalances, which may affect respiratory function. In children, prolonged vomiting can result in metabolic alkalosis due to loss of gastric acid. This condition can further complicate the respiratory status, potentially leading to changes in ventilation patterns and respiratory rate.

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Related Practice

Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

c. Respiratory compensation for metabolic acidosis consists of hypoventilation.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

d. Renal compensation for metabolic alkalosis consists of reabsorption of hydrogen ions and secretion of bicarbonate ions.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

e. You would expect to find an elevated Pco₂ in arterial blood gas analysis of a patient with respiratory acidosis.

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Textbook Question

Diabetic ketoacidosis is characterized by an increased level of ketone bodies, which causes metabolic acidosis. A patient in diabetic ketoacidosis will have an altered rate of ventilation. Will the patient be hyperventilating or hypoventilating? How will a change in the rate and depth of ventilation compensate for an acidosis that is metabolic in nature?

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Textbook Question

Ms. Johanssen is a patient in the hospital. The nurse examines her laboratory reports and notices that she has developed hyperkalemia and acidosis over the past several days. On closer examination of her medical chart, the nurse also sees that her physician recently doubled her dose of spironolactone, an aldosterone-blocking diuretic. How does this explain her laboratory findings?

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Textbook Question

A laboratory printout of arterial blood gases indicates that a patient has an increased Pco₂ , decreased pH, and normal bicarbonate ion concentration. Is this patient in acidosis or alkalosis? Is the pH disturbance respiratory or metabolic in nature? Explain your reasoning. How long do you think the patient has had this pH disturbance? (Hint: Look at the bicarbonate ion concentration. What system controls the concentration of bicarbonate ions, and how quickly does it compensate for pH disturbances?)

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Multiple Choice

Hyperventilation can lead to __________.

One way the kidneys maintain HCO₃^– balance is by __________.

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