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Sepsis and Septic Shock

By

Joseph D Forrester

, MD, MSc, Stanford University

Last full review/revision Sep 2021| Content last modified Sep 2021
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  • Usually, sepsis results from certain bacterial infections, often acquired in a hospital.

  • Having certain conditions, such as a weakened immune system, certain chronic disorders, an artificial joint or heart valve, and certain heart valve abnormalities, increases the risk.

  • At first, people have a high (or sometimes low) body temperature, sometimes with shaking chills and weakness.

  • As sepsis worsens, the heart beats rapidly, breathing becomes rapid, people become confused, and blood pressure drops.

  • Doctors suspect the diagnosis based on symptoms and confirm it by detecting bacteria in a sample of blood, urine, or other material.

  • Antibiotics are given immediately, along with oxygen and fluids by vein and sometimes drugs to increase blood pressure.

Usually, the body’s response to infection is limited to the specific area infected, for example symptoms of a urinary tract infection are often limited to the bladder. But in sepsis, the response to infection occurs throughout the body—called a systemic response.

Although many infections cause such symptoms throughout the body, in sepsis organs begin to malfunction and blood flow becomes inadequate to parts of the body.

Septic shock is sepsis that causes dangerously low blood pressure (shock Shock Shock is a life-threatening condition in which blood flow to the organs is low, decreasing delivery of oxygen and thus causing organ damage and sometimes death. Blood pressure is usually low... read more ). As a result, internal organs such as the lungs, kidneys, heart, and brain, typically receive too little blood, causing them to malfunction. Septic shock is diagnosed when blood pressure remains low despite intensive treatment with fluids by vein. Septic shock is life threatening.

Causes of Sepsis and Septic Shock

Sepsis occurs when toxins produced by certain bacteria cause cells in the body to release substances that trigger inflammation (cytokines Innate Immunity One of the body's lines of defense (immune system) involves white blood cells (leukocytes) that travel through the bloodstream and into tissues, searching for and attacking microorganisms and... read more ). Although cytokines help the immune system fight infection, they can have harmful effects:

  • They can cause the blood vessels to widen (dilate), decreasing blood pressure.

  • They can cause blood to clot in tiny blood vessels inside organs.

Most often, sepsis is caused by infection with certain kinds of bacteria that are usually acquired in a hospital. Rarely, fungi, such as Candida, cause sepsis. Infections that can lead to sepsis begin most commonly in the lungs, abdomen, or urinary tract. In most people, these infections do not lead to sepsis. However, sometimes bacteria spread into the bloodstream (a condition called bacteremia Bacteremia Bacteremia is the presence of bacteria in the bloodstream. Bacteremia may result from ordinary activities (such as vigorous toothbrushing), dental or medical procedures, or from infections ... read more ). Sepsis may then develop. If the initial infection involves an abscess, the risk of bacteremia and sepsis is increased. Occasionally, such as in toxic shock syndrome Toxic Shock Syndrome Toxic shock syndrome is a group of rapidly progressive and severe symptoms that include fever, rash, dangerously low blood pressure, and failure of several organs. It is caused by toxins produced... read more , sepsis is triggered by toxins released by bacteria that have not spread into the bloodstream.

Complications of Sepsis and Septic Shock

The decreased blood pressure and small clots lead to a series of harmful complications:

All of these effects result in a vicious circle of worsening organ malfunction:

  • The kidneys excrete little or no urine, and metabolic waste products (such as urea nitrogen) accumulate in the blood.

  • The walls of blood vessels may leak, allowing fluid to escape from the bloodstream into tissues and cause swelling.

  • Lung function worsens because blood vessels in the lungs leak fluid, which accumulates, making breathing difficult.

Risk Factors of Sepsis and Septic Shock

The risk of sepsis is increased in people with conditions that reduce their ability to fight serious infections. These conditions include the following:

The risk is also increased in people who are more likely to have bacteria enter their bloodstream. Such people include those who have a medical device inserted into the body (such as a catheter inserted into a vein or the urinary tract, drainage tubes, or breathing tubes). When medical devices are inserted, they can move bacteria into the body. Bacteria may also collect on the surface of such devices, making infection and sepsis more likely. The longer the device is left in place, the greater the risk.

Other conditions also increase the risk of sepsis:

Symptoms of Sepsis and Septic Shock

Most people have a fever, but some have a low body temperature. People may have shaking chills and feel weak. Other symptoms may also be present depending on the type and location of the initial infection (for example, people with pneumonia may have cough, chest discomfort and trouble breathing). Breathing, heart rate, or both may be rapid.

As sepsis worsens, people become confused and less alert. The skin becomes warm and flushed. The pulse is rapid and pounding, and people breathe rapidly. People urinate less often and in smaller amounts, and blood pressure decreases. Later, body temperature often falls below normal, and breathing becomes very difficult. The skin may become cool and pale and mottled or blue because blood flow is reduced. Reduced blood flow may cause tissue, including tissue in vital organs (such as the intestine), to die, resulting in gangrene Gas Gangrene Gas gangrene is a life-threatening infection of muscle tissue caused mainly by the anaerobic bacteria Clostridium perfringens and several other species of clostridia. Gas gangrene can develop... read more .

When septic shock develops, blood pressure is low despite treatment. Some people die.

Diagnosis of Sepsis and Septic Shock

  • Culture of a blood sample

  • Tests to find the source of infection (tests usually include chest x-rays and other imaging tests and cultures of fluid or tissue samples)

Doctors usually suspect sepsis when a person who has an infection suddenly develops a very high or low temperature, a rapid heart rate or breathing rate, or low blood pressure.

To confirm the diagnosis, doctors look for bacteria in the bloodstream (bacteremia Bacteremia Bacteremia is the presence of bacteria in the bloodstream. Bacteremia may result from ordinary activities (such as vigorous toothbrushing), dental or medical procedures, or from infections ... read more ), evidence of another infection that could be causing sepsis, and an abnormal number of white blood cells in a blood sample.

Samples of blood are taken to try to grow (culture Culture of Microorganisms Infectious diseases are caused by microorganisms, such as bacteria, viruses, fungi, and parasites. Doctors suspect an infection based on the person's symptoms, physical examination results,... read more ) the bacteria in the laboratory (a 1- to 3-day process). However, if people have been taking antibiotics for their initial infection, bacteria may be present but may not grow in the culture. Sometimes catheters are removed from the body, and the tips are cut off and sent for culture. Finding bacteria in a catheter that had contact with the blood indicates that bacteria are probably in the bloodstream.

To check for other infections that may cause sepsis, doctors take samples of fluids or tissue, such as urine, cerebrospinal fluid, tissue from wounds, or sputum coughed up from the lungs. These samples are cultured and checked for bacteria.

Other tests are done to look for signs of organ malfunction and other complications of sepsis. They may include the following:

Prognosis of Sepsis and Septic Shock

Without treatment, most people with septic shock die. Even with treatment, there is a significant risk of death. On average, about 30 to 40% of people with septic shock die. However, the risk of death varies greatly depending on many factors, including how quickly people are treated, the type of bacteria involved (particularly whether the bacteria are resistant to antibiotics Antibiotic Resistance Antibiotics are drugs used to treat bacterial infections. They are ineffective against viral infections and most other infections. Antibiotics either kill microorganisms or stop them from reproducing... read more ) and the person's underlying health status.

Treatment of Sepsis and Septic Shock

  • Antibiotics

  • Intravenous fluids

  • Oxygen

  • Removal of the source of infection

  • Sometimes drugs to increase blood pressure

Doctors immediately treat sepsis and septic shock with antibiotics. Doctors do not wait until test results confirm the diagnosis because a delay in antibiotic treatment greatly decreases the chances of survival. Treatment occurs in a hospital.

People with septic shock or who are severely ill are immediately admitted to an intensive care unit for treatment.

Antibiotics

When choosing the initial antibiotics, doctors consider which bacteria are most likely to be present, which depends on where the infection started, for example the bacteria that cause urinary tract infection are typically different from the bacteria that cause skin infection. Also, doctors consider what bacteria are most common in infections in the person's community and in their particular hospital. Often, two or three antibiotics are given together to increase the chances of killing the bacteria, particularly when the source of the bacteria is unknown. Later, when the test results are available, doctors can substitute the antibiotic that is most effective against the specific bacteria causing the infection.

Intravenous fluids

People with septic shock are also given large amounts of fluid by vein (intravenously) to increase the amount of fluid in the bloodstream and thus increase blood pressure. Giving too little fluid is not effective but giving too much fluid can cause severe lung congestion.

Oxygen

Oxygen is given through a mask, through nasal prongs, or through a breathing (endotracheal) tube if one has been inserted. If needed, a mechanical ventilator Mechanical Ventilation Mechanical ventilation is use of a machine to aid the movement of air into and out of the lungs. Some people with respiratory failure need a mechanical ventilator (a machine that helps air get... read more (a machine that helps air get into and out of the lungs) is used to help with breathing.

Removal of the source of infection

If present, abscesses are drained. Catheters, tubes, or other medical devices that may have started the infection are removed or changed. Surgery may be done to remove infected or dead tissue.

Other treatments

If intravenous fluids do not increase blood pressure, doctors sometimes give drugs, such as vasopressin or norepinephrine (which cause blood vessels to narrow), to raise blood pressure and increase blood flow to the brain, heart, and other organs. However, because these drugs may narrow blood vessels within organs, they sometimes decrease the amount of blood flow through the organs.

Sometimes people who have septic shock develop a high blood sugar (glucose) level. Because high blood sugar impairs how the immune system responds to an infection, doctors give insulin by vein to people to lower the level of glucose in the blood.

Corticosteroids (such as hydrocortisone) may be given by vein to people whose blood pressure remains low despite having received adequate fluids and drugs to increase blood pressure and despite having the source of their infection treated.

Drugs Mentioned In This Article

Generic Name Select Brand Names
LEVOPHED
CORTEF, SOLU-CORTEF
VASOSTRICT
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