What is Sepsis?

  • A whole-body inflammatory response to infection.
  • Usually caused by bacteria in the blood.
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What is the Pathophysiology of Sepsis?

  • Bacteria enter the bloodstream through damaged tissues.
  • Cellular change in neutrophils making them live longer.
  • Mast cells detect antigens and trigger an immune response.  Secrete factors that mediate vasodilation and vascular constriction.
  • Invading pathogen stimulates release of cytokines by macrophages.  Cytokines stimulate movement of cells towards the site of infection.
  • Blood vessels become leaky allowing white blood cells to enter the tissues.
  • Blood vessels dilate due to inflammatory response.  Capillaries leak blood and fluid.  Risk of low blood pressure.
  • Platelets release blood-clotting proteins at the wound site.  Can't keep up with the breakage of blood vessels, causing blood to spill into the tissues.
  • Causes fluid build up in tissues.  Excess fluid makes it harder for oxygen to get through.
  • Inadequate tissue perfusion leads to cellular hypoxia and lactic acidosis.
  • Fluid leaving blood vessels causes decreased circulation volume, decreasing blood pressure
  • Temperature increases in response to infection.  Pyrogens influence hypothalamus to increase metabolic reactions.
  • Due to blood clotting, blood is unable to get to organs, causing them to stop functioning due to lack of oxygen.
  • Neutrophils and macrophages remove pathogens through phagocytosis.
  • Blood vessels are damaged so oxygen is not absorbed properly, causing acute respiratory distress.
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What are the Symptoms of Sepsis?

  • Tachycardia - Heart rate increases in response to reduced circulation volume, fever and chemical inflammatory mediators (e.g. histamine).
  • Tachypnoea - Respiratory rate increases to compensate for metabolic acidosis.  The brainstem is stimulated to cause lungs to expel CO2.
  • Fever - Body temperature raises in response to the presence of infection.  Pyrogens influence the hypothalamus to increase metabolic reactions.
  • Cyanosis - Caused by reduced blood flow to the pulmonary system, reducing adequate gaseous exchange.
  • Mottled Skin/Cool Peripheries - Caused by reduced blood flow to the skin and peripheries.  Secondary to hypotension and abnormal regulation of blood flow.
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What are the Treatments for Sepsis?

  • IV Fluids - to restore circulation volume.
  • IV Antibiotics - to eradicate the infection.
  • Oxygen - to reduce work of breathing and improve oxygen saturations.
  • Antipyretics - reduce fever.
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