Acid-Base Balance Basics Quiz

Basics of Acid-Base

• Water is an essential component of maintaining acid-base balance.
• Oxygen levels are inversely proportional to acidity, low oxygen increases acidity.
• Carbon dioxide (CO2) levels directly increase acidity.
• Electrolytes like potassium (K+), sodium (Na+), and calcium (Ca2+) play a role in regulating acid-base balance.
• Glucose from food is metabolized and can contribute to acid production.

Acid-Base Basics

• Water dissociates into hydrogen ions (H+) and hydroxyl ions (OH-).
• Hydrogen ions (H+) represent acidity, while hydroxyl ions (OH-) represent alkalinity.
• pH measures the concentration of hydrogen ions, with a normal pH of 7.35-7.45.
• A solution with a high hydrogen ion concentration is acidic, resulting in a low pH.
• Acidosis is a state of low pH, below 7.45.
• Any disruption to homeostasis, including fluid balance, respiration, gastrointestinal function, etc., can lead to acid-base imbalances.

Factors Influencing Acid-Base Balance

• Airway: Obstruction leads to hypoventilation, increasing CO2 and resulting in acidosis.
• Breathing: Hypoventilation (CO2 retention) increases acidity, hyperventilation (CO2 removal) lowers acidity.
• Circulation: Hypovolemia (dehydration) leads to acidosis, while hypervolemia (overhydration) can lead to alkalosis.
• Nutrition: Upper GI tract (acidic, HCL): Vomiting results in metabolic alkalosis. Lower GI tract (alkaline, KOH): Diarrhea results in metabolic acidosis.
• Renal Function: Kidneys regulate bicarbonate (HCO3-) levels, low levels cause acidosis, high levels cause alkalosis. Oliguria (low urine output) can lead to acidosis, while polyuria (increased urine output) can lead to alkalosis.

Arterial Blood Gases (ABGs)

• ABGs are a blood test to measure acid-base balance.
• pH: 7.35 – 7.45 (Indicates acidosis if below 7.45)
• Partial pressure of carbon dioxide (PaCO2): 35 – 45 (Indicates respiratory component)
• Partial pressure of oxygen (PaO2): 80 - 100 (Indicates oxygen levels)
• Oxygen saturation (SpO2): 95-100 (Indicates oxygen saturation)
• Bicarbonate (HCO3-): 22 – 26 (Indicates metabolic component)

Acid-Base Equation

• Homeostasis: H2O + CO2 ⇌ H2CO3 ⇌ HCO3- + H+
• Respiratory Component: H2O + CO2 ⇌ H2CO3
• Metabolic Component: H2CO3 ⇌ HCO3- + H+

Causes of Acid-Base Imbalances

• Respiratory Acidosis/Alkalosis: Caused by imbalances in CO2 levels.
  • Hypoventilation: Increased CO2 above 45 mmHg (hypercapnia) leads to respiratory acidosis.
  • Hyperventilation: Decreased CO2 below 35 mmHg leads to respiratory alkalosis.
• Metabolic Acidosis: Low pH, low bicarbonate. Often caused by diarrhea.
• Metabolic Alkalosis: High pH, high bicarbonate. Often caused by vomiting.
• Mixed Acid-Base Imbalance: When two or more acid-base imbalances occur simultaneously.

Acid-Base Control Systems

• Chemical Buffer : Blood buffers regulate hydrogen ions.
• Respiratory Buffer: Lungs regulate carbon dioxide levels.
• Renal Buffer: Kidneys regulate bicarbonate levels through urine.

Interpreting ABGs

• Example 1: ABG = 7.32/50/25.
  • pH below 7.45 = Acidosis
  • PaCO2 = 50 indicates increased CO2, thus, respiratory acidosis.
  • HCO3 = 25 is within normal range.
• Example 2: ABG = 7.55/43/32.
  • pH above 7.45 = Alkalosis
  • PaCO2 = 43 is within normal range.
  • HCO3 = 32, increased bicarbonate, indicating metabolic alkalosis.

Basic Rules of Acid-Base Imbalances

• Increased pH (Alkalosis): Most vital organs (brain, heart, lungs, kidneys, liver, pancreas) function increase, except for potassium concentration (hypokalemia).
  • Brain: Hyperreflexia (overactive reflexes), seizures.
  • Heart: Increased heart rate, arrhythmias.
  • Lungs: Increased respiratory rate.
  • Kidneys: Increased urine output.
  • Liver: Decreased liver function.
  • Pancreas: Decreased insulin production.

Basics of Acid-Base

• Water is essential for acid-base balance
• Sources of acid and base:
  • Water (H2O): fluids
  • Oxygen (O2): low levels mean acidosis
  • Carbon dioxide (CO2): directly proportional to acid increase
  • Electrolytes (K+, Na+, Ca2+)
  • Food (glucose)
• Basic formula: H2O = H+ + OH-
  • H+ = acid
  • OH- = base
• pH = Power (concentration) of hydrogen ion
  • Normal pH = 7.35 – 7.45
  • Acidosis = pH < 7.35
  • Alkalosis = pH > 7.45
• Any changes in homeostasis (fluid, respiration, GIT) can lead to acid-base imbalance

Respiratory Influences

• Airway obstruction leads to hypoventilation, increased CO2, and acidosis.
• Hypoventilation (CO2 retention) results in acidosis.
• Hyperventilation (CO2 removal) results in alkalosis.

Circulatory Influences

• Hypovolemia (dehydration) results in acidosis.
• Hypervolemia (overhydration) results in alkalosis.

Nutritional Influences

• Upper GIT (acid = HCL): vomiting leads to metabolic alkalosis.
• Lower GIT (base = KOH): diarrhea leads to metabolic acidosis.
• Renal system:
  • Bicarbonate: low levels lead to acidosis, high levels lead to alkalosis.
  • Oliguria (reduced urine output) leads to acidosis.
  • Polyuria (increased urine output) leads to alkalosis.

ABGs

• Arterial Blood Gases (ABGs) measure:
  • pH (7.35 - 7.45)
  • PaCO2 (35 - 45) = Respiratory
  • PaO2 (80 - 100)
  • SpO2 (95 - 100)
  • HCO3- (22 - 26) = Metabolic

Acid-Base Equation

• H2O + CO2 = H2CO3 = HCO3- + H+ = Homeostasis
• H2O + CO2 = H2CO3 = Respiratory
• H2CO3 = HCO3- + H+ = Metabolic
• Causes:
  • Respiratory disorder = Respiratory acidosis/alkalosis = CO2 imbalance
    • Hypoventilation = CO2 > 45 (acidosis)
    • Hyperventilation = CO2 < 45 (alkalosis)
    • Hypoxia = SpO2 low
  • Metabolic acidosis = low pH = low bicarbonate = diarrhea
  • Metabolic alkalosis = high pH = high bicarbonate = vomiting
  • Mixed acid-base imbalance

Acid-Base Control

• Chemical buffer: controls hydrogen ions in the blood (blood)
• Respiratory buffer: carbon dioxide ions in the blood (lungs)
• Renal buffer: bicarbonate ions in the urine (kidney)

ABGs Interpretation

• Example: ABG = 7.32 / 50 / 25
  • pH < 7.35 = Respiratory acidosis
  • CO2 > 45 = Respiratory component
  • HCO3 = Normal
• Example: ABG = 7.55 / 43 / 32
  • pH > 7.45 = Alkalosis
  • CO2 = Normal
  • HCO3 = High = Metabolic Alkalosis

Basic Rules of Acid-Base Imbalances

• When pH increases (alkalosis), the function of vital organs (brain, heart, lungs, kidneys, liver, pancreas) increases, except for potassium concentration (hypokalemia).
  • Brain: hyperreflexia, seizures
  • Heart: increased rate and contractility
  • Lungs: increased respiratory rate
  • Kidneys: increased urine output