Septic Shock Health Article

Definition

Septic shock is a syndrome in which a potentially lethal drop in blood pressure occurs as a result of an overwhelming bacterial infection.

KEY TERMS

Bacteremia—Invasion of the bloodstream by bacteria.

Description

Septic shock is a possible consequence of bacteremia, which is also called sepsis. Bacterial toxins, and the immune system's response to them, can cause a dramatic drop in blood pressure and may result in under-perfusion to various organs. Septic shock can lead to multiple organ failure, including respiratory failure, and may cause rapid death. Toxic shock syndrome is one type of septic shock.

Causes and symptoms

During an infection, certain bacteria can release complex molecules, called endotoxins, that may provoke a dramatic response by the body's immune system. Endotoxins are particularly dangerous; as they become widely dispersed, they cause arteries and the smaller arterioles to dilate. At the same time, the walls of the blood vessels become leaky, allowing fluid to seep into the tissues, lowering intravascular volume (the amount of fluid left in circulation). This combination, of arterial dilation and decreased intravascular volume, causes a dramatic decrease in blood pressure and impaired blood flow to multiple organs. Other changes seen in septic shock are disseminated intravascular coagulation (DIC), which can further impair organ perfusion (blood flow).

Septic shock is seen most often in patients with impaired host defenses (patients who are immunosuppressed), and is often due to nosocomial (hospitalacquired) infections. The immune system is suppressed by drugs used to treat cancer, autoimmune disorders, organ transplants, and diseases of immune deficiency such as AIDS. Malnutrition, chronic drug abuse, and long-term illness also increase the likelihood of succumbing to bacterial infection. Bacteremia is more likely with preexisting infections such as urinary or gastrointestinal tract infections, or skin ulcers. Bacteria may be introduced to the blood stream by surgical procedures, catheters, or intravenous equipment.

Toxic shock syndrome (TSS) is a potentially fatal disorder resulting from infection with Staphylococcus aureus, a toxin-producing strain of a bacteria. When it was first reported about 25 years ago, toxic shock syndrome was associated with menstruation and linked to super-absorbent tampon use. Today, it is recognized that use of super-absorbent tampons does increase the risk of TSS, as does use of a contraceptive sponge or diaphragm. Postpartum patients (women who have just given birth) and patients with wound infections, or recovering from nasal surgery also are at risk for TSS. The illness appears suddenly, with fever, rash, low blood pressure, and episodes of fainting. Survival has improved since the 1980s, approximately 2–5% of patients die from this dis-order. Patients recovering from TSS face increased risk of recurrence. To prevent TSS, menstruating women are advised to avoid use of super-absorbent tampons.