HJBR Jan/Feb 2024

26 JAN / FEB 2024 I  HEALTHCARE JOURNAL OF BATON ROUGE   What is sepsis? What are its causes, and why is it so deadly? O’Neal The technical definition of sepsis is “life-threatening organ dysfunction due to a dysregulated host response to infection.” When we get an infection, it is the job of the immune system — made up of different kinds of white blood cells — to respond to the infection, wherever it is, and eliminate it. If everything goes well, this immune response — the “host response” — only occurs at the site of the infection. Once the infection is resolved, the immune system returns to its resting state. Sometimes, though, the host response is too vigorous and disorganized, or “dysregulated,” and spreads beyond the area of the infection. This abnormal immune response is at the heart of sepsis, and it can result in damage to vital organs — kidneys, liver, lungs, heart, brain, etc. — that may not be involved in the original infection at all. In the extreme form, this damage to vital organs is irreversible and can lead to severe consequences, including death. It is important to understand that any infection can result in sepsis. The infection, or what we refer to as the source of sepsis, could be pneumonia, a kidney infection, or a bloodstream infection. Also, the cause of the infection could be any type of organisms, including bacteria, viruses, and fungi. How has the understanding of sepsis evolved over time? O’Neal One of the most important changes we have seen in our understanding of sepsis over time has been our increased awareness and understanding of the host response itself. The earliest definitions of sepsis included changes in temperature (for example, fever), white blood cell count, heart rate, and respiratory rate. If these things occurred in the setting of an infection, we called that sepsis. Ultimately, though, we realized that, sometimes, these changes are a very normal, highly regulated response to an infection; also, we found that up to 15% of patients with sepsis did not meet those criteria. Because of all of this, we began to focus on the abnormal immune response as the underlying cause of sepsis. This improved understanding has allowed us to focus our efforts on measuring the immune response as a way to diagnose sepsis, and, possibly, identify targets that we can treat, hopefully preventing some of the life-threatening organ dysfunction and improving the outcomes of the disease. Who is most susceptible to sepsis? O’Neal Everybody is susceptible to sepsis, and we see it occurring in some of the healthiest people as well as some of the sickest. That said, the people who are at the highest risk of sepsis tend to be older and sicker at baseline than those at lowest risk. There are a lot of reasons for this. For one, as we age, our bodies and immune systems change, and we are less able to tolerate serious problems like infections. For example, the same immune response that may make a young, healthy patient feel bad may result in severe organ damage to an older, frail patient. Also, patients with abnormal immune systems, like patients on chemotherapy or on immunosuppression, are at increased risk, because their immune response may be impaired by the treatment they are on. What are the symptoms of sepsis? What is the difference between sepsis and septic shock? O’Neal Because sepsis is an interaction between a pathogen, or the “bug”that causes an infection, and the person who is infected, or the “host,” the signs and symptoms are highly variable. In fact, there is no one set of symptoms or signs of infection that doctors can rely on to diagnose sepsis, and this is because of the wide variety in both the pathogen that causes the infection and the host response to it. Because of this, the diagnosis of sepsis usually starts with a suspicion of the infection that causes it, so we begin by looking for evidence of an infection. Symptoms, which are subjective, are things patients report to us like pain in an area, shortness of breath, cough, nausea, or generally feeling bad. In addition to symptoms, healthcare providers also look for signs of infection, which are objective. These signs might be fever, elevated white count, redness of a certain area, or things we find on special tests like X-rays. Once we suspect an infection, then we begin by looking for evidence of organ dysfunction. The problem with this is that the organ dysfunction, which is life-threatening, is the result of the abnormal immune response, so, by the time we see it, it may be very late in the course of the disease. This problem is why we have worked so hard to find a SEPSIS