Distributive shock is, as in hypovolemic shock, caused by an insufficient intravascular volume of blood. This form of relative hypovolemia is the result of blood vessel dilation.

Examples of this form of shock are:

• • Septic shock - This is caused by an overwhelming infection leading to vasodilation, such as by Gram negative bacteria i.e. Escherichia coli which releases an endotoxin which produces adverse biochemical, immunological and occasionally neural mechanisms which are harmful to the body. It is treated by antibiotics, fluid replacement, and vasoconstrictors.
  • Anaphylactic shock - Caused by a severe anaphylactic reaction to an allergen, antigen, drug or foreign protein causing the release of histamine which causes widespread vasodilation. Leading to hypotension and increase capillary permeability.
  • Acute adrenal insufficiency is not infrequently the result of discontinuing corticosteroid treatment without tapering the dosage.
  • Neurogenic shock. Neurogenic shock is the rarest form of shock. It is caused by trauma to the spinal cord resulting in the sudden loss of autonomic and motor reflexes below the injury level. Without stimulation by sympathetic nervous system the vessel walls relax uncontrolled, resulting in a sudden decrease in peripheral vascular resistance, leading to vasodilation and hypotension.

References

• Intensive Care Medicine by Irwin and Rippe
• The ICU Book by Marino
• Procedures and Techniques in Intensive Care Medicine by Irwin and Rippe
• Fundamental Critical Care Support, A standardized curriculum of Critical Care, by the Society of Critical Care Medicine