Why Sepsis Causes Low Blood Pressure

Sepsis, when severe, can lead to septic shock and death. One reason is bacterial infections which cause systemic reactions in the body also cause our immune system to release cytokines to fight the infection. In a typical infection, the cytokines will dilate the blood vessels at the site of the infection to allow more blood to pass through the area, carrying the cells and mediators needed to fight the bacteria. However, in sepsis, the response involves the entire body with inflammation essentially occurring everywhere.

With systemic response, all blood vessels dilate causing the blood pressure to drop. Instead of assisting in fighting the infection, the body’s response to sepsis actually slows down blood flow making our immune system less effective. The bacteria can damage vital organs and lack of blood flow can spark organ failure. Organ failure and low blood pressure are the two biggest dangers for severe sepsis and septic shock, making it a fatal condition for up to 40-50% of patients.