An infection can start with a simple injury—like a shallow cut on the arm—that allows bacteria and other microbes to slip into your body’s tissue or circulation. Your immune system is designed to detect these foreign invaders, launch an attack, and kill the infectious microbes—but sometimes the defense doesn’t work as planned. 

When this happens, the infection progresses and the immune system battles even harder by releasing more infection-fighting chemicals. In rare cases, rather than being helpful, these extra chemicals begin to overwhelm the body. As in a game of dominoes, this can then lead to further failures of the body’s processes. 

Sepsis occurs when an already-present infection spirals out of control and begins to cause organ damage, and even death. The term “septic shock” is used to describe what’s happening when a person’s blood pressure is low, oxygen delivery to vital organs is compromised, and the threat of death is imminent. 

About 1.7 million U.S. adult cases of sepsis occur each year, and nearly 270,000 die from the condition. Sepsis can be difficult to diagnose immediately, which makes general awareness about it all the more important. “It is one of the leading causes of death in the United States, on par with cancer and heart disease,” says Yale Medicine emergency physician John Sather, MD. “Sepsis is challenging because often the inciting event is a common infection. Patients often don’t think of common infections as potentially deadly ones.” 

While septic shock can be fatal, many patients can make a complete recovery if they are diagnosed and treated early with antibiotics, intravenous fluids, and blood pressure support. At Yale Medicine, our physicians are involved in research to find ways to detect sepsis earlier and potential new treatment options.

Sepsis is a life-threatening condition that is caused by any type of infection a person already has—it can be bacterial, fungal, or viral—and the complex immune response that attempts to fight it. The immune system itself, while an important component of the body’s defense against infection, produces chemicals that can inadvertently cause leaky or clotted blood vessels, loss of circulating blood volume, low blood pressure, organ failure and/or death.    

Sepsis can affect anyone at any age, but especially susceptible are infants (under 12 months), pregnant women, older adults, and people with chronic health conditions like diabetes and/or weakened immune systems.

Sepsis is most commonly associated with the following types of infections:

• Lung infections (like pneumonia)
• Urinary tract infections
• Skin infections (especially burns)
• Infections of the digestive system 

Because sepsis can happen quickly, it is important to be alert for early signs. The most common signs include the following:

• Source of infection (cough, sore throat, abdominal pain, pain with urination) and fevers
• High heart rate
• Shortness of breath
• Confusion or disorientation
• Lightheadedness and/or low blood pressure
• Decreased urine output

“Patients can play an important role in their care by recognizing early symptoms that might be associated with sepsis,” Dr. Sather says. 

A single diagnostic test for sepsis does not yet exist, and so doctors and healthcare professionals use a combination of tests and immediate and worrisome clinical signs, which include the following:

• The presence of an infection
• Very low blood pressure and high heart rate
• Increased breathing rate

Doctors will also do tests to try to confirm the presence—and possibly type—of infection. A urine sample can provide information about urinary tract infections (UTI) or kidney problems. Markers found in the blood can show that the immune system has gone into an over-reactive mode.

 Blood tests may reveal the following signs suggestive of sepsis:

• Elevated or low white blood cells – Higher than usual levels of leukocytes, known as white blood cells (WBCs), are a sign of a current infection, while too few WBCs indicate that a person is at higher risk of developing one.
• Lactic acid – When organs and muscles do not receive enough oxygen, they can release lactic acid. A high level of this in the blood can indicate that an infection is present.
• Markers of organ dysfunction – Creatinine levels (which test kidney function), enzymes (to check liver function), and cardiac biomarkers. 

Researchers now believe that the development of sepsis depends not only on the initial infection type, but also on a person’s age, sex, previous chronic health conditions, and genetic factors. As a result, current sepsis research is focused on gathering additional background data, like those mentioned above, on patients who are labeled “at risk” of sepsis due to their initial diagnosis or reason for hospitalization.        

The earlier sepsis is detected and treated, the better odds a person with the condition has for full recovery. People who have developed sepsis—and most especially those who have progressed into septic shock—are usually transferred to a hospital’s intensive care unit for supportive care and close monitoring. Septic shock is treated with intravenous fluids, antibiotics, medications to maintain blood pressure, and mechanical ventilation, as needed. Additional treatments such as steroids, vitamins, and surgery to control the source of infection are sometimes required.

Yale Medicine strives to provide patients with sepsis swift access to a high quality of care. It maintains a quality assurance program focused on sepsis detection, compliance with best practice recommendations, and optimal patient experience.

“At Yale Medicine, we have a multidisciplinary team that can recognize sepsis early and implement evidence-based strategies to prevent related complications,” Dr. Sather says.