Sepsis is a life-threatening condition that arises when the body’s response to infection causes injury to its own tissues and organs. Common signs and symptoms include fever, increased heart rate, increased breathing rate, and confusion. There also may be symptoms related to a specific infection, such as a cough with pneumonia, or painful urination with a kidney infection. In the very young, old, and people with a weakened immune system, there may be no symptoms of a specific infection and the body temperature may be low or normal, rather than high. Severe sepsis causes poor organ function or insufficient blood flow. Insufficient blood flow may be evident by low blood pressure, high blood lactate, or low urine output.  Septic shock is low blood pressure due to sepsis that does not improve after reasonable amounts of intravenous fluids are given.

Sepsis is caused by an immune response triggered by an infection.  Most commonly, the infection is bacterial, but it may also be from fungi, viruses, or parasites. Common locations for the primary infection include lungs, brain, urinary tract, skin, and abdominal organs.  Risk factors include young or old age, a weakened immune system from conditions such as cancer or diabetes, major trauma, or burns. Sepsis is usually treated with intravenous fluids and antibiotics.

Signs and symptoms

Sepsis is frequently associated with either fever, low body temperature, rapid breathing, elevated heart rate, confusion, and edema. Early signs are a rapid heart rate, decreased urination, and high blood sugar. Signs of established sepsis include confusion, metabolic acidosis (which may be accompanied by faster breathing and lead to a respiratory alkalosis), low blood pressure due to decreased systemic vascular resistance, higher cardiac output, and dysfunctions of blood coagulation (where clotting may lead to organ failure).

The drop in blood pressure seen in sepsis may lead to shock. This may result in light-headedness. Bruising or intense bleeding may occur.

Cause

The most common primary sources of infection resulting in sepsis are the lungs, the abdomen, and the urinary tract. Typically, 50 per cent of all sepsis cases start as an infection in the lungs. No definitive source is found in one third to one half of cases.

Infections leading to sepsis usually are bacterial, but may be fungal or viral.