Cardiac Arrest causes (4H & 4T)

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Potential Causes of Cardiac Arrest: The 4 H’s and 4 T’s

The 4 H’s

  1. Hypoxia:
  • Description: Lack of oxygen in the blood.
  • Causes: Respiratory failure, airway obstruction, low oxygen levels in the environment, carbon monoxide (CO) poisoning, high altitude.
  • Management: Ensure adequate ventilation and oxygenation, address the underlying cause, use hyperbaric oxygen therapy for CO poisoning.

2. Hypovolemia:

  • Description: Low blood volume.
  • Causes: Severe dehydration, haemorrhage, excessive fluid loss, severe burns, gastrointestinal losses (vomiting, diarrhoea).
  • Management: Rapid volume replacement with intravenous fluids or blood products, manage the underlying cause of fluid loss.

3. Hypothermia/Hyperthermia

  • Description: Abnormally low body temperature.
  • Causes: Prolonged exposure to cold environments, submersion in cold water.
  • Management: Gradual rewarming using blankets, warm IV fluids, and other warming techniques.

4. Hypo-/Hyperkalemia and Other Metabolic Disturbances (Hydrogen Ions H+ pH):

  • Description: Abnormal levels of potassium or other significant electrolyte/metabolic imbalances, including hypoglycemia.
  • Causes: Renal failure, excessive potassium intake, severe vomiting or diarrhoea, untreated diabetes.
  • Management: Correct the electrolyte imbalance (e.g., calcium chloride, insulin with glucose, and sodium bicarbonate for hyperkalemia; cautious potassium administration for hypokalemia). Administer glucose for hypoglycemia.

The 4 T’s

  1. Tension Pneumothorax:
  • Description: Accumulation of air in the pleural space under pressure, compressing the lungs and heart.
  • Causes: Chest trauma, mechanical ventilation, underlying lung disease.
  • Management: Immediate needle decompression followed by chest tube insertion.

2. Tamponade (Cardiac):

  • Description: Accumulation of fluid in the pericardium, leading to reduced cardiac output.
  • Causes: Trauma, pericarditis, myocardial infarction, malignancy.
  • Management: Pericardiocentesis to remove the fluid.

3. Toxins (Drug Overdose):

  • Description: Poisoning by drugs or other substances.
  • Causes: Overdose of medications, recreational drugs, exposure to toxic substances.
  • Management: Administer appropriate antidotes, supportive care, consider activated charcoal if appropriate, and perform decontamination if needed.

4. Thrombosis (Pulmonary or Coronary):

    • Description: Blood clot blocking major vessels.
    • Pulmonary Thrombosis: Blockage of the pulmonary arteries (pulmonary embolism).
      • Causes: Deep vein thrombosis (DVT) traveling to the lungs.
      • Management: Anticoagulation, thrombolysis, or surgical embolectomy.
    • Coronary Thrombosis: Blockage of the coronary arteries (acute myocardial infarction).
      • Causes: Atherosclerosis, plaque rupture.
      • Management: Percutaneous coronary intervention (PCI), thrombolytics, antiplatelet therapy.