Sepsis

Sepsis (also referred to as blood poisoning) is a potentially life-threatening condition that arises when the body's dysregulated response to infection causes injury to its own tissues and organs. This initial stage of sepsis is followed by dysregulation of the immune system. Common signs and symptoms include fever, increased heart rate, increased breathing rate, and confusion. There may also be symptoms related to a specific infection, such as a cough with pneumonia, or painful urination with a kidney infection. 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. Severe sepsis may cause organ dysfunction and significantly reduced blood flow. The presence of low blood pressure, high blood lactate, or low urine output may suggest poor blood flow. Septic shock is low blood pressure due to sepsis that does not improve after fluid replacement or requires medications to raise the blood pressure. Sepsis is caused by many organisms, including bacteria, viruses, and fungi. Gram-negative and Gram-positive bacteria are the most common causes of sepsis; when caused by bacteria, it is also referred to as septicaemia. Viral pathogens and diarrhoeal illnesses are common causes in children. In 60–70% of cases, an infectious pathogen is found. Common locations for the primary infection include the lungs, brain, urinary tract, skin, and abdominal organs. Risk factors include being very young or old, a weakened immune system from conditions such as cancer or diabetes, major trauma, and burns. A shortened sequential organ failure assessment score (SOFA score), known as the quick SOFA score (qSOFA), has replaced the SIRS system of diagnosis. 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. Sepsis guidelines recommend obtaining blood cultures before starting antibiotics; however, the diagnosis does not require the blood to be infected. Medical imaging is helpful when looking for the possible location of the infection. Other potential causes of similar signs and symptoms include anaphylaxis, adrenal insufficiency, low blood volume, heart failure, and pulmonary embolism. Sepsis requires immediate treatment with intravenous fluids and antimicrobial medications. Ongoing care and stabilization often continues in an intensive care unit. 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. Mechanical ventilation and dialysis may be needed to support the function of the lungs and kidneys, respectively. A central venous catheter and arterial line may be placed for access to the bloodstream and to guide treatment. Other helpful measurements include cardiac output and superior vena cava oxygen saturation. People with sepsis need preventive measures for deep vein thrombosis, stress ulcers, and pressure ulcers unless other conditions prevent such interventions. Some people might benefit from tight control of blood sugar levels with insulin. The use of corticosteroids is controversial, with some reviews finding benefit, others not. A person's age, immune system function, the virulence of the pathogen causing infection, and the amount of microorganisms in the body causing infection (pathogen burden) all affect the incidence, severity, and prognosis of sepsis. 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%. Sepsis affected about 49 million people in 2017, with 11 million deaths (1 in 5 deaths worldwide). In the developed world, approximately 0.2 to 3 people per 1000 are affected by sepsis yearly. Rates of disease have been increasing. 85% of cases occurred in low or middle income countries with 40% of cases worldwide occurring in Sub-Saharan Africa. Some data indicate that sepsis is more common among men than women; however, other data show a greater prevalence of the disease among women.

Signs and symptoms In addition to symptoms related to the actual cause, people with sepsis may have a fever, low body temperature, rapid breathing, a fast heart rate, confusion, and edema. Early signs include a rapid heart rate, decreased urination, and high blood sugar. Signs of established sepsis include confusion, metabolic acidosis (which may be accompanied by a faster breathing rate that leads to respiratory alkalosis), low blood pressure due to decreased systemic vascular resistance, higher cardiac output, and disorders in blood-clotting that may lead to organ failure. Fever is the most common presenting symptom in sepsis, but fever may be absent in some people, such as the elderly or those who are immunocompromised. The drop in blood pressure seen in sepsis can cause lightheadedness and is part of the criteria for septic shock. Oxidative stress is observed in septic shock, with circulating levels of copper and vitamin C being decreased. Diastolic blood pressure falls during the early stages of sepsis, causing a widening/increasing of pulse pressure, which is the difference between the systolic and diastolic blood pressures. If sepsis becomes severe and hemodynamic compromise advances, the systolic pressure also decreases, causing a narrowing/decreasing of pulse pressure. A pulse pressure of over 70 mmHg in patients with sepsis is correlated with an increased chance of survival. A widened pulse pressure is also correlated with an increased chance that someone with sepsis will benefit from and respond to IV fluids.

Cause

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