Sepsis

Sepsis is a potentially life-threatening condition that arises when the body's dysregulated response to infection causes injury to its own tissues and organs.^[4][6]

This initial stage of sepsis is followed by dysregulation of the immune system.^[7] Common signs and symptoms include fever, increased heart rate, increased breathing rate, and confusion.^[1] There may also be symptoms related to a specific infection, such as a cough with pneumonia, or painful urination with a kidney infection.^[2] The very young, old, and people with a weakened immune system may not have any symptoms specific to their infection, and their body temperature may be low or normal instead of constituting a fever.^[2] Severe sepsis may cause organ dysfunction and significantly reduced blood flow.^[8] The presence of low blood pressure, high blood lactate, or low urine output may suggest poor blood flow.^[8] Septic shock is low blood pressure due to sepsis that does not improve after fluid replacement or requires medications to raise the blood pressure.^[8][9]

Sepsis is caused by many organisms including bacteria, viruses, and fungi.^[10] Gram negative and gram positive bacteria are the most common causes of sepsis. Viral pathogens and diarrheal illnesses are common causes in children.^[9] In 60-70% of cases an infectious pathogen is found.^[9] Common locations for the primary infection include the lungs, brain, urinary tract, skin, and abdominal organs.^[2] Risk factors include being very young or old, a weakened immune system from conditions such as cancer or diabetes, major trauma, and burns.^[1] A shortened sequential organ failure assessment score (SOFA score), known as the quick SOFA score (qSOFA), has replaced the SIRS system of diagnosis.^[4] qSOFA criteria for sepsis include at least two of the following three: increased breathing rate, change in the level of consciousness, and low blood pressure.^[4] Sepsis guidelines recommend obtaining blood cultures before starting antibiotics; however, the diagnosis does not require the blood to be infected.^[2] Medical imaging is helpful when looking for the possible location of the infection.^[8] Other potential causes of similar signs and symptoms include anaphylaxis, adrenal insufficiency, low blood volume, heart failure, and pulmonary embolism.^[2]

Sepsis requires immediate treatment with intravenous fluids and antimicrobial medications.^[1][5] Ongoing care and stabilization often continues in an intensive care unit.^[1] If an adequate trial of fluid replacement is not enough to maintain blood pressure, then the use of medications that raise blood pressure becomes necessary.^[1] Mechanical ventilation and dialysis may be needed to support the function of the lungs and kidneys, respectively.^[1] A central venous catheter and arterial line may be placed for access to the bloodstream and to guide treatment.^[8] Other helpful measurements include cardiac output and superior vena cava oxygen saturation.^[8] People with sepsis need preventive measures for deep vein thrombosis, stress ulcers, and pressure ulcers unless other conditions prevent such interventions.^[8] Some people might benefit from tight control of blood sugar levels with insulin.^[8] The use of corticosteroids is controversial, with some reviews finding benefit,^[11][12] others not.^[13]

A person's age, immune system function, the virulence of the pathogen causing infection, the amount of microorganisms in the body causing infection (pathogen burden) all affect the incidence, severity and prognosis of sepsis.^[9][14] The risk of death from sepsis is as high as 30%, while for severe sepsis it is as high as 50%, and the risk of death from septic shock is 80%.^[15][16][14] Sepsis affected about 49 million people in 2017, with 11 million deaths (1 in 5 deaths worldwide).^[17] In the developed world, approximately 0.2 to 3 people per 1000 are affected by sepsis yearly.^[14][18] Rates of disease have been increasing.^[8] 85% of cases occurred in low or middle income countries with 40% of cases worldwide occurring in Sub-Saharan Africa.^[9] Some data indicate that sepsis is more common among men than women,^[2] however, other data show a greater prevalence of the disease among women.^[17]