F/E & A/B LECTURE 4

Introduction to Acid-Base Balance

• The concept of acid-base balance is complex and requires thorough understanding of physiological processes.

• Acid-base balance is crucial for maintaining homeostasis in the body, impacting cellular functions and metabolic pathways.

• Recommended to read chapter sections and review charts for clarity on nuanced concepts.

Understanding Acid-Base Balance

• Refers to the body's hydrogen ion (H+) concentration, which is vital for regulating various biochemical reactions.

• Measured by pH: a logarithmic scale reflecting hydrogen ion concentration in blood.

• Normal pH range for arterial blood: 7.35 - 7.45; deviations can adversely affect organ function and overall health.

• pH regulation is essential for proper body functioning, as enzymes, hormones, and metabolic processes depend on specific pH ranges to operate effectively.

Definitions

• Acid: A substance that dissociates and releases hydrogen ions in a solution, increasing acidity.

• Base: A substance that combines with hydrogen ions, reducing the hydrogen ion concentration and increasing pH.

• An inverse relationship exists between hydrogen ions and pH; increased hydrogen ions lead to lower pH (more acidic environment) and vice versa.

• The balance between acids and bases is critical for maintaining physiological processes.

pH Scale

• Below 7.35: Acidosis, indicating an increase in H+ concentration.

• Above 7.45: Alkalosis, indicating a decrease in H+ concentration.

• Normal pH: 7.35–7.45 is critical for health; deviations below 6.8 or above 7.8 can be fatal.

• pH imbalances can lead to significant clinical issues, affecting oxygen transport and enzyme function.

Major Components In Acid-Base Balance

• Bicarbonate (HCO3): The primary anion in extracellular fluid, playing a significant role in buffering pH and maintaining alkali reserves.

• Carbonic Acid (H2CO3): The main acid in the body, formed from the combination of CO2 and water.

• Maintaining a 1:20 ratio of carbonic acid to bicarbonate is crucial for pH stability and proper physiological functioning.

• Any alterations in this ratio can lead to various acid-base disorders.

Body's Mechanisms for pH Regulation

• Blood Buffers: Fast-acting buffers that neutralize pH shifts within seconds, providing immediate support against environmental changes.

  • These systems absorb hydrogen ions if acid is present or release hydrogen ions if a base is present.

  • Common buffer systems include:

    • Bicarbonate and Carbonic Acid: The primary buffering system in the blood.

    • Phosphate: Important in intracellular fluid and urine buffering.

    • Proteins (e.g., hemoglobin, albumin, globulins): Contribute to buffering by binding or releasing hydrogen ions.

• Respiratory System: The second line of defense, making adjustments over minutes to maintain pH stability.

  • Controls CO2 levels through respiration rates:

    • Increased respiration decreases CO2 (raises pH), thereby correcting acidosis.

    • Decreased respiration retains CO2 (lowers pH), thereby compensating for alkalosis.

• Kidneys: The slowest response, taking hours to days to adjust, but are crucial for long-term regulation.

  • The kidneys adjust blood pH through excreting or absorbing acids or bases.

  • They retain bicarbonate if pH is low or excrete bicarbonate if pH is high, providing a critical compensatory mechanism during imbalances.

Types of Acid-Base Imbalances

• Acidosis: Defined as a pH < 7.35 and can result from either excess acid production or insufficient base (bicarbonate).

  • Categories:

    • Respiratory Acidosis: Retention of CO2 due to hypoventilation or lung diseases such as COPD leads to increased acidity.

    • Metabolic Acidosis: Loss of bicarbonate (e.g., diarrhea) or excessive acid production (e.g., diabetic ketoacidosis).

• Alkalosis: Defined as a pH > 7.45, which may result from insufficient acid or excessive base.

  • Categories:

    • Respiratory Alkalosis: Caused by hyperventilation, leading to loss of CO2.

    • Metabolic Alkalosis: Increased bicarbonate levels (e.g., vomiting) or decreased acid levels (e.g., potassium depletion).

Signs and Symptoms of Acidosis

• Symptoms include weakness, disorientation, and potential coma.

• Kussmaul's respirations: Deep, rapid breathing pattern that occurs as a compensatory mechanism to expel CO2 and increase pH.

• Possible hyperkalemia (high potassium levels) and hypotension, indicating potential complications.

Signs and Symptoms of Alkalosis

• Symptoms may include irritability, confusion, convulsions, and in severe cases, death.

• Muscle hypertonicity and shallow respirations may also occur, along with hypokalemia (low potassium levels).

Nursing Diagnoses

• For Acidosis: Nursing diagnoses may include decreased cardiac output, risk for fluid volume excess, risk for injury, impaired gas exchange, and ineffective airway clearance.

• For Alkalosis: Nursing diagnoses may include ineffective breathing pattern, risk for impaired gas exchange, and deficient fluid volume, indicating the need for careful monitoring.

Additional Learning Resources

• Review related chapter boxes (e.g., metabolic acidosis box on page 498) for further clarification on specific conditions.

• Utilize videos and diagrams for enhanced understanding of acid-base balance, ABGs (Arterial Blood Gases), and the implications for clinical practice.

Conclusion

• Acid-base balance is a complex but crucial aspect of physiology, influencing various bodily functions and health outcomes.

• Understanding the mechanisms, potential imbalances, and their implications is essential in nursing practice to ensure effective patient care and clinical outcomes.

• Continuous education on this topic is critical, given its relevance in critical care and daily clinical practice.