Which form of shock results from chemical mediators released during an allergic reaction, causing systemic vasodilation and capillary leakage?

• A. Anaphylactic Shock
• B. Septic Shock
• C. Neurogenic Shock
• D. Tension Pneumothorax

Answer: (A)

An allergic reaction triggers release of chemical mediators from mast cells and basophils, including histamine, leukotrienes, and others. These mediators cause widespread vasodilation and increased capillary permeability, so fluid leaks into tissues and the circulating volume drops. The result is systemic hypotension and poor perfusion, which is the hallmark of anaphylactic shock. The same mediators can also cause airway swelling and bronchoconstriction, complicating breathing and requiring rapid management.

Septic shock involves vasodilation and capillary leak too, but its root cause is infection and toxins rather than an allergy. Neurogenic shock comes from loss of sympathetic tone after spinal injury, leading to hypotension with often warm, dry skin and a different pattern of perfusion changes. Tension pneumothorax is an obstructive problem from air in the pleural space trapping the lung and compressing the heart, causing decreased venous return and chest sign changes, not a mediator-driven allergic reaction.