Sepsis is a serious medical condition. It's caused by an overwhelming immune response to infection. The body releases immune chemicals into the blood to combat the infection. Those chemicals trigger widespread inflammation, which leads to blood clots and leaky blood vessels. As a result, blood flow is impaired, and that deprives organs of nutrients and oxygen and leads to organ damage.

In severe cases, one or more organs fail. In the worst cases, blood pressure drops, the heart weakens, and the patient spirals toward septic shock. Once this happens, multiple organs—lungs, kidneys, liver—may quickly fail, and the patient can die.

Sepsis is a major challenge in hospitals, where it’s one of the leading causes of death. It's also a main reason why people are readmitted to the hospital. Sepsis occurs unpredictably and can progress rapidly.

Sepsis associated with HYPOTENSION or hypoperfusion despite adequate fluid resuscitation. Perfusion abnormalities may include, but are not limited to LACTIC ACIDOSIS; OLIGURIA; or acute alteration in mental status.

What is sepsis?

Sepsis is your body's overactive and extreme response to an infection. Sepsis is a life-threatening medical emergency. Without quick treatment, it can lead to tissue damage, organ failure, and even death.

What causes sepsis?

Sepsis happens when an infection you already have triggers a chain reaction throughout your body. Bacterial infections are the most common cause, but other types of infections can also cause it.

The infections are often in the lungs, stomach, kidneys, or bladder. It's possible for sepsis to begin with a small cut that gets infected or with an infection that develops after surgery. Sometimes, sepsis can occur in people who didn't even know that they had an infection.

Who is at risk for sepsis?

Anyone with an infection could get sepsis. But certain people are at higher risk:

• Adults 65 or older
• People with chronic conditions, such as diabetes, lung disease, cancer, and kidney disease
• People with weakened immune systems
• Pregnant women
• Children younger than one

What are the symptoms of sepsis?

Sepsis can cause one or more of these symptoms:

• Rapid breathing and heart rate
• Shortness of breath
• Confusion or disorientation
• Extreme pain or discomfort
• Fever, shivering, or feeling very cold
• Clammy or sweaty skin

It's important to get medical care right away if you think you might have sepsis or if your infection is not getting better or is getting worse.

What other problems can sepsis cause?

Severe cases of sepsis can lead to septic shock, where your blood pressure drops to a dangerous level and multiple organs can fail.

How is sepsis diagnosed?

Your health care provider may use many tools to make a diagnosis:

• A medical history, which includes asking about your symptoms
• A physical exam, including checking vital signs (your temperature, blood pressure, heart rate, and breathing)
• Lab tests that check for signs of infection or organ damage
• Imaging tests such as an x-ray or a CT scan to find the location of the infection

Many of the signs and symptoms of sepsis can also be caused by other medical conditions. This may make sepsis hard to diagnose in its early stages.

What are the treatments for sepsis?

It is very important to get treatment right away. Treatment usually includes:

• Antibiotics
• Maintaining blood flow to organs. This may involve getting oxygen and intravenous (IV) fluids.
• Treating the source of the infection
• If needed, medicines to increase blood pressure

In serious cases, you might need kidney dialysis or a breathing tube. Some people need surgery to remove tissue damaged by the infection.

Can sepsis be prevented?

To prevent sepsis, you should try to prevent getting an infection:

• Take good care of any chronic health conditions that you have
• Get recommended vaccines
• Practice good hygiene, such as handwashing
• Keep cuts clean and covered until healed

Bacteria can enter the circulatory and lymphatic systems through acute infections or breaches of the skin barrier or mucosa. Breaches may occur through fairly common occurrences, such as insect bites or small wounds. Even the act of tooth brushing, which can cause small ruptures in the gums, may introduce bacteria into the circulatory system. In most cases, the bacteremia that results from such common exposures is transient and remains below the threshold of detection. In severe cases, bacteremia can lead to septicemia with dangerous complications such as toxemia, sepsis, and septic shock. In these situations, it is often the immune response to the infection that results in the clinical signs and symptoms rather than the microbes themselves.

Bacterial Sepsis, Septic and Toxic Shock

At low concentrations, pro-inflammatory cytokines such as interleukin 1 (IL-1) and tumor necrosis factor-α (TNF-α) play important roles in the host’s immune defenses. When they circulate systemically in larger amounts, however, the resulting immune response can be life threatening. IL-1 induces vasodilation (widening of blood vessels) and reduces the tight junctions between vascular endothelial cells, leading to widespread edema. As fluids move out of circulation into tissues, blood pressure begins to drop. If left unchecked, the blood pressure can fall below the level necessary to maintain proper kidney and respiratory functions, a condition known as septic shock. In addition, the excessive release of cytokines during the inflammatory response can lead to the formation of blood clots. The loss of blood pressure and occurrence of blood clots can result in multiple organ failure and death.

Bacteria are the most common pathogens associated with the development of sepsis, and septic shock. The most common infection associated with sepsis is bacterial pneumonia, accounting for about half of all cases, followed by intra-abdominal infections and urinary tract infections. Infections associated with superficial wounds, animal bites, and indwelling catheters may also lead to sepsis and septic shock.

These initially minor, localized infections can be caused by a wide range of different bacteria, including Staphylococcus, Streptococcus, Pseudomonas, Pasteurella, Acinetobacter, and members of the Enterobacteriaceae. However, if left untreated, infections by these gram-positive and gram-negative pathogens can potentially progress to sepsis, shock, and death.

If a gram-negative bacterial infection reaches the bloodstream, large quantities of LPS can be released into the blood, resulting in a syndrome called septic shock. Death due to septic shock is a real danger. The overwhelming immune and inflammatory responses that occur with septic shock can cause a perilous drop in blood pressure; intravascular blood clotting; development of thrombi and emboli that block blood vessels, leading to tissue death; failure of multiple organs; and death of the patient.

Many people have never heard of sepsis, or they don’t know what it is. But sepsis is one of the top 10 causes of disease-related death in the United States. The condition can arise suddenly and progress quickly, and it’s often hard to recognize.

Sepsis was once commonly known as “blood poisoning.” It was almost always deadly. Today, even with early treatment, sepsis kills about 1 in 5 affected people. It causes symptoms such as fever, chills, rapid breathing, and confusion.

Anyone can get sepsis, but the elderly, children, and infants are most vulnerable. People with weakened immune systems, severe burns, physical trauma, or long-term illnesses (such as diabetes, cancer, or liver disease) are also at increased risk.

At one time, sepsis was thought to arise from an overgrowth of bacteria or other germs in the bloodstream. We now know that sepsis actually springs from 2 factors: first an infection (such as pneumonia or a urinary tract infection) and then a powerful and harmful response by your body’s own immune system.

“With sepsis, the fight between the infection and the body’s immune response makes the body like a battleground,” says Dr. Derek Angus, a critical care physician at the University of Pittsburgh School of Medicine. “In the case of severe sepsis, that fight results in vital organ dysfunction, which puts one’s life in peril.”

Severe sepsis can damage essential organs like the liver and kidneys. An even more extreme disorder occurs when blood pressure plummets—a condition known as septic shock. “With septic shock, the immune response that’s trying to fight infection can actually lead to a dangerous drop in blood pressure,” Angus says. As blood pressure falls, tissues become starved for oxygen-rich blood. Organs can fail, which could lead to death.

By some estimates, severe sepsis or septic shock strikes nearly 1 million Americans each year. At least 200,000 of them die in the hospital shortly afterward. Many who survive recover completely. But others have lasting problems, including permanent organ damage and thinking difficulties (such as problems with planning, organizing, and multitasking).

Sepsis can be triggered by many types of infections. “But the most common cause of sepsis is community–acquired pneumonia,” Angus says. Scientists are still working to understand why some people with infections develop severe sepsis or septic shock while others don’t.

Researchers are exploring new ways to diagnose, reverse, or prevent this serious and costly condition. Treatment for sepsis is most successful if the condition is spotted early and then treated quickly with antibiotics to fight the infection and fluids to maintain blood pressure.

In a large NIH-funded clinical trial of sepsis care, Angus and his colleagues found that a relatively simple strategy worked as well at preventing deaths as did more complex and costly approaches. “The study helped to clarify that a lot of the treatment steps we’d been using are essential, but the extra steps with sophisticated and invasive procedures aren’t always necessary to improve survival,” Angus says.

Sepsis is a health emergency that requires swift medical care.

Signs of Sepsis

Sepsis can be hard to spot, because its early symptoms are similar to many other conditions. Medical personnel look for these signs:

• Fever or low body temperature (hypothermia)
• Chills
• Rapid heart rate
• Difficulty breathing
• Skin rash
• Confusion and disorientation
• Light-headedness caused by a sudden drop in blood pressure

The loss of too much blood may lead to circulatory shock, a life-threatening condition in which the circulatory system is unable to maintain blood flow to adequately supply sufficient oxygen and other nutrients to the tissues to maintain cellular metabolism. It should not be confused with emotional or psychological shock. Typically, the patient in circulatory shock will demonstrate an increased heart rate but decreased blood pressure, but there are cases in which blood pressure will remain normal. Urine output will fall dramatically, and the patient may appear confused or lose consciousness. Urine output less than 1 mL/kg body weight/hour is cause for concern. Unfortunately, shock is an example of a positive-feedback loop that, if uncorrected, may lead to the death of the patient.

There are several recognized forms of shock:

• Hypovolemic shock in adults is typically caused by hemorrhage, although in children it may be caused by fluid losses related to severe vomiting or diarrhea. Other causes for hypovolemic shock include extensive burns, exposure to some toxins, and excessive urine loss related to diabetes insipidus or ketoacidosis. Typically, patients present with a rapid, almost tachycardic heart rate; a weak pulse often described as “thread;” cool, clammy skin, particularly in the extremities, due to restricted peripheral blood flow; rapid, shallow breathing; hypothermia; thirst; and dry mouth. Treatments generally involve providing intravenous fluids to restore the patient to normal function and various drugs such as dopamine, epinephrine, and norepinephrine to raise blood pressure.
• Cardiogenic shock results from the inability of the heart to maintain cardiac output. Most often, it results from a myocardial infarction (heart attack), but it may also be caused by arrhythmias, valve disorders, cardiomyopathies, cardiac failure, or simply insufficient flow of blood through the cardiac vessels. Treatment involves repairing the damage to the heart or its vessels to resolve the underlying cause, rather than treating cardiogenic shock directly.
• Vascular shock occurs when arterioles lose their normal muscular tone and dilate dramatically. It may arise from a variety of causes, and treatments almost always involve fluid replacement and medications, called inotropic or pressor agents, which restore tone to the muscles of the vessels. In addition, eliminating or at least alleviating the underlying cause of the condition is required. This might include antibiotics and antihistamines, or select steroids, which may aid in the repair of nerve damage. A common cause is sepsis (or septicemia), also called “blood poisoning,” which is a widespread bacterial infection that results in an organismal-level inflammatory response known as septic shock. Neurogenic shock is a form of vascular shock that occurs with cranial or spinal injuries that damage the cardiovascular centers in the medulla oblongata or the nervous fibers originating from this region. Anaphylactic shock is a severe allergic response that causes the widespread release of histamines, triggering vasodilation throughout the body.
• Obstructive shock, as the name would suggest, occurs when a significant portion of the vascular system is blocked. It is not always recognized as a distinct condition and may be grouped with cardiogenic shock, including pulmonary embolism and cardiac tamponade. Treatments depend upon the underlying cause and, in addition to administering fluids intravenously, often include the administration of anticoagulants, removal of fluid from the pericardial cavity, or air from the thoracic cavity, and surgery as required. The most common cause is a pulmonary embolism, a clot that lodges in the pulmonary vessels and interrupts blood flow. Other causes include stenosis of the aortic valve; cardiac tamponade, in which excess fluid in the pericardial cavity interferes with the ability of the heart to fully relax and fill with blood (resulting in decreased preload); and a pneumothorax, in which an excessive amount of air is present in the thoracic cavity, outside of the lungs, which interferes with venous return, pulmonary function, and delivery of oxygen to the tissues.