F/E & A/B Lecture 3

  • Introduction to Acid-Base Balance

    • Acid-base balance is a complex concept referring to the concentration of hydrogen ions in the body.

    • pH is the measurement of hydrogen ion concentration in the blood.

    • Normal blood pH must be maintained between 7.35 and 7.45 for proper bodily functions.

  • Definitions

    • Acids: Substances that dissociate and release hydrogen ions in a solution.

    • Bases: Substances that combine with hydrogen ions in a solution.

    • Acid-base balance: The regulation of arterial blood pH through hydrogen ion control (production and elimination).

    • Bicarbonate (HCO3): The primary anion in extracellular fluid, plays a crucial role in maintaining acid-base balance.

  • Hydrogen Ion Concentration and pH

    • More hydrogen ions result in higher acidity and lower pH.

    • Inverse relationship exists between hydrogen ion concentration and pH levels.

    • Blood pH lower than 7.35 indicates acidosis; greater than 7.45 indicates alkalosis.

  • Acid-Base Regulation Mechanisms

    • Blood Buffers: Act as the first line of defense, neutralizing pH changes in seconds.

    • Four primary buffer systems include:

      • Bicarbonate and carbonic acid

      • Phosphate

      • Protein (Albumin and globulins)

      • Hemoglobin

    • Respiratory System: Regulates pH by adjusting carbon dioxide levels through respiratory rate. Takes minutes to respond.

    • Kidneys: Control pH by excreting or retaining acids/bases. Takes hours to days to respond.

  • Acid-Base Imbalances

    • Two types of imbalances: Acidosis and Alkalosis.

    • Can be acute (sudden) or chronic (long-term).

    • Acidosis: Serum pH < 7.35, due to excess acid or insufficient base.

    • Divided into metabolic (loss of bicarbonate or excess acid) and respiratory (retention of carbon dioxide).

    • Alkalosis: Serum pH > 7.45, due to insufficient acid or excess base.

    • Divided into metabolic (excess bicarbonate or loss of acid) and respiratory (hyperventilation).

  • Metabolic Acidosis

    • Caused by loss of bicarbonate or increase in acid (e.g., diabetic ketoacidosis, renal failure).

    • Symptoms: Weakness, disorientation, Kussmaul's respirations (deep, rapid breaths to eliminate CO2).

    • Kussmaul’s respirations: A compensatory mechanism aimed at reducing blood acidity.

  • Respiratory Acidosis

    • Caused by excessive carbon dioxide retention (e.g., COPD, narcotic overdose).

    • Symptoms: Hypoventilation, lethargy, confusion, possible coma.

  • Metabolic Alkalosis

    • Caused by loss of acid (e.g., vomiting) or excessive bicarbonate intake (e.g., antacids).

    • Symptoms: Irritability, muscle cramping, possible convulsions.

  • Respiratory Alkalosis

    • Caused by excessive CO2 excretion due to hyperventilation (e.g., anxiety, fever).

    • Symptoms: Rapid breathing, dizziness, numbness, and seizures.

  • Nursing Diagnoses Related to Acid-Base Imbalances

    • Acidosis:

    • Decreased cardiac output

    • Risk for fluid volume excess

    • Risk for injury (neurological changes)

    • Impaired gas exchange

    • Ineffective airway clearance

    • Alkalosis:

    • Ineffective breathing pattern

    • Risk for impaired gas exchange

    • Deficient fluid volume

  • Conclusion

    • Acid-base balance is essential for homeostasis; understanding it aids in recognizing and managing various medical conditions.

    • Review diagrams and charts for visual learning and seek clarification on complex topics in acid-base homeostasis.