Acid-Base Balance and Imbalances

Acid-Base Balance

• pH reflects the concentration of hydrogen ions (H+) in a solution.
• It measures a solution's acidity or alkalinity.
• pH and hydrogen ion concentration are inversely related.
  • Lower pH means higher acidity.
• Acids and bases neutralize each other, needing to stay balanced in the body.
• Acidosis involves higher extracellular hydrogen ions.
• Alkalosis involves lower extracellular hydrogen ions.
• Acid-base imbalances often link to potassium balance issues.
  • Kidneys move hydrogen and potassium in opposite ways.
    • Acidosis results in hydrogen excretion and potassium reabsorption.
    • Alkalosis results in potassium excretion and hydrogen absorption.
• Calcium ions can exit cells when hydrogen ions flood in.

Types of Acid-Base Imbalance

• Bicarbonate level changes cause metabolic acidosis or alkalosis.
• Respiratory issues cause respiratory acidosis or alkalosis due to pH changes.
• The body starts compensatory actions when buffering systems can't fix an acid-base problem.

Respiratory Acidosis

• Hypoventilation causes respiratory acidosis.
• The renal buffering system helps with this.
• Causes:
  • Airway and upper airway diseases.
  • Aspiration and laryngospasm.
  • Obstructive sleep apnea.
  • Pulmonary diseases like asthma and COPD.
  • Acute respiratory distress, pneumonia, and pulmonary edema.
  • Muscular dystrophy and multiple sclerosis.
  • Obesity hypoventilation syndrome.
  • Closed head injury and chest trauma.
  • Respiratory or cardiac arrest.
• Ventilation problems lead to fast, severe acidosis, which kidneys can't quickly fix.
• Signs and symptoms:
  • Systemic/cerebral vasodilation.
  • Headache and lightheadedness.
  • Restlessness.
  • Warm, flushed skin.
  • CNS depression, nausea, and vomiting.
• COPD can raise the risk of acidosis over time.
• Poor lung function results in carbonic acid build-up and rising pH.
• Sodium bicarbonate might be needed to fix imbalances.

Respiratory Alkalosis

• Hyperventilation causes respiratory alkalosis.
• Hyperventilation lowers blood carbon dioxide, reducing carbonic acid.
• Kidneys hold onto hydrogen ions to balance the low acid.
• Hydrogen ions move from outside cells to inside.
• Causes of hyperventilation and respiratory alkalosis:
  • Medications.
  • CNS stimulation.
  • Pulmonary issues.
• Signs and symptoms:
  • Lightheadedness.
  • Carpal pedal spasms.
  • Chest tightness, palpitations, vertigo, and blurred vision.

Metabolic Acidosis

• Metabolic acidosis isn't related to the respiratory system.
• Kussmaul breathing or increased breathing rate compensates for it.
• The body tries to fix acid-base balance by removing extra CO2 through breathing.
• Kidneys retain bicarbonate ions and remove hydrogen ions in urine.
• Causes:
  • Lactic acid from anaerobic respiration.
  • Ketoacidosis from metabolized fatty acids.
  • GI losses; ingestion of drugs or toxins.
• Clinical presentation:
  • Headache and drowsiness.
  • Loss of appetite.
  • Kussmaul breathing, nausea, vomiting.
  • Cardiac dysrhythmias.

Metabolic Alkalosis

• Metabolic alkalosis happens when too much acid is lost from urine or gastric acid.
• It's common in long-term illness.
• Contributing factors:
  • GI losses from excessive vomiting.
  • Too much water intake, nasogastric suctioning.
  • Too many alkaline substances like antacids.
• Signs and symptoms:
  • Weakness and confusion.
  • Muscle tremors and cramps.
  • Cardiac dysrhythmias.

Cellular Injury

• How cellular injury or death shows depends on cell number and type damaged.
• Causes:
  • Hypoxia and ischemia.
  • Chemical injury and infection/sepsis.
  • Immunologic and physical damage.
  • Inflammatory injury.
• Manifestations:
  • Microscopic and functional abnormalities.
• Common microscopic abnormalities:
  • Cell swelling.
  • Rupture of cellular membranes with breakdown of nuclear material/membranes.
• High-level functional disturbances:
  • Inefficient oxygen use.
  • Intracellular acidosis with toxic waste accumulation.
  • Derangement of nutrient metabolism.
• Cell changes affect the organism, causing minor issues or organ system collapse.
• One system's problems affect others.
• Repair is possible with proper treatment.
• Irreversible injury means cell death, leading to necrosis.
• Necrosis involves cell breakdown.
  • Cell membrane becomes too permeable.
  • Cells and organelles swell.
  • Lysosomes release enzymes and components.

Hypoxic Injuries

• Hypoxic injuries result from less oxygen, due to:
  • Less oxygen in the air.
  • Poor hemoglobin function.
  • Low red blood cell count.
  • Respiratory/cardiovascular disease, or loss of cytochromes.
• Cells without oxygen for a few seconds make mediators, damaging nearby or distant areas.
• Free radicals are the earliest and most dangerous mediators.
• Free radicals lack one electron in the outer shell, causing instability.
• They attack cells and membranes randomly, causing widespread tissue damage.

Chemical Injuries

• Chemical injuries include poisoning.
• Types of poisons:
  • Cyanide induces cell hypoxia by blocking oxidative phosphorylation in mitochondria.
  • Pesticides block an enzyme, preventing proper nerve impulse transmission.
  • Lead causes long-term brain injury and neurologic dysfunction from long-term ingestion.
    • It replaces calcium in blood because of similar size.
  • Carbon monoxide binds to hemoglobin more easily than oxygen.
    • Low levels cause nausea, vomiting, and headache.
    • Higher levels can lead to death.
  • Ethanol causes inebriation at lower levels.
    • High doses depress the CNS, causing hypoventilation and cardiovascular collapse.
  • Pharmacological agents create toxic products when metabolized.

Infectious Injuries

• Infectious injuries result from bacteria, viruses, or fungi invasion.
• Bacteria injure by direct action on cells or by producing toxins.
• Viruses start an inflammatory response, damaging cells.
• Virulence measures a microorganism's disease-causing ability.
• Pathogenicity refers to microorganism's ability to reproduce and cause disease.
• Growth and survival depend on body defenses and bacteria's resistance.
• Newborns, older adults, and those with diabetes, cancer, or chronic diseases typically have weaker immune systems.
• Bacteria have a capsule, protecting them from white blood cells ingestion and destruction.
• Categorized with gram staining.
  • Gram staining involves staining a suspension purple with iodine, decolorizing with alcohol, and staining with red dye.
  • Bacteria resisting decolorization are gram-positive.
  • Bacteria accepting the counter stain are gram-negative.
• Bacteria make exotoxins or endotoxins that can harm cells.
  • Exotoxins are produced in cells and released into tissues/fluids; they are poisonous.
    • Inactive exotoxins are used for vaccines.
  • Endotoxins are part of gram-negative bacteria cell walls, causing inflammation, fever, chills, malaise, and septic shock.
• White blood cells go to the injury site and release endogenous pyrogens, causing fever.
• The body's common response to bacteria is inflammation.
• Some bacteria cause hypersensitivity reactions.
• Bacteremia means bacteria are in the blood.
• Septicemia refers to systemic disease caused by microorganisms in the blood.
• Viruses are intracellular parasites, taking over the host cell's metabolic processes for replication.
  • They have a nucleic acid core (RNA or DNA) and a capsid (protein layer).
  • Replication happens inside the host cell.
  • They disrupt normal metabolic processes.
  • Antibiotics cannot reach them, as they live and replicate inside the host cell.
  • Symbiotic relationships between a virus and normal cells might cause unapparent persistent infection.

Immunologic and Inflammatory Injury

• Inflammation is a protective response to injury, infection, or hypoxia.
• It can be caused by physical, chemical, or microbiological agents.
• Tissue injury leads to mediators causing capillary dilation.
  • Leads to increased blood flow and capillary permeability.
  • Includes exudation of fluid.
  • Also, attraction of leukocytes and migration of white cells to the injury site.
• Systemic response includes fever.
• Local effects involve dilation/expansion of blood vessels, heat, redness, tenderness, swelling, and pain.
• Severe systemic effects include temperature elevation and increased white blood cell count.
• Outcome depends on tissue damage.
  • Mild inflammation returns tissue to normal.
  • Severe cases destroy tissue, needing repair with scar tissue.
  • Cell membranes might be injured, causing potassium leaks; water flows in, swelling the cell.