Sepsis

Sepsis refers to a bacterial infection in the bloodstream or body tissues. This is a very broad term covering the presence of many types of microscopic disease-causing organisms.

Sepsis is also called bacteremia. Closely related terms include septicemia and septic syndrome. In the general population, the incidence of sepsis is twopeople in 10,0000.

Sepsis can originate anywhere bacteria can gain entry to the body; common sites include the genitourinary tract, the liver and its bile ducts, the gastrointestinal tract, and the lungs. Broken or ulcerated skin can also provide access to bacteria commonly present in the environment. Invasive medical procedures, including dental work, can introduce bacteria or permit it to accumulate. Entry points and equipment left in place for any length of time present a particular risk. Heart valve replacement, catheters, ostomy sites, intravenous(IV) or arterial lines, surgical wounds, or surgical drains are examples. IVdrug users are at high risk as well.

People with inefficient immune systems or blood disorders are at particular risk for sepsis and have a higher death rate (up to 60%); in people who have no underlying chronic disease, the death rate is far lower (about 5%). The growing problem of antibiotic resistance has increased the incidence of sepsis,partly because ordinary preventive measures (such as prophylactic antibiotics) are less effective.

The most common symptom of sepsis is fever, often accompanied by chills or shaking, or other flu-like symptoms. A history of any recent invasive procedureor dental work should raise the suspicion of sepsis and medical help shouldbe sought.

The presence of sepsis is indicated by blood tests showing particularly highor low white blood cell counts. The causative agent is determined by blood culture.

Identifying the specific causative agent ultimately determines how sepsis istreated. However, time is of the essence, so a broad-spectrum antibiotic or multiple antibiotics will be administered until blood cultures reveal the culprit and treatment can be made specific to the organism. Intravenous antibiotic therapy is usually necessary and is administered in the hospital.

Septic shock is a potentially lethal drop in blood pressure due to the presence of bacteria in the blood.

Septic shock is a possible consequence of bacteremia, or bacteria in the bloodstream. Bacterial toxins, and the immune system response to them, cause a dramatic drop in blood pressure, preventing the delivery of blood to the organs. Septic shock can lead to multiple organ failure including respiratory failure, and may cause rapid death. Toxic shock syndrome is one type of septic shock.

During an infection, certain types of bacteria can produce and release complex molecules, called endotoxins, that may provoke a dramatic response by the body's immune system. Released in the bloodstream, endotoxins are particularlydangerous, because they become widely dispersed and affect the blood vesselsthemselves. Arteries and the smaller arterioles open wider, increasing the total volume of the circulatory system. At the same time, the walls of the blood vessels become leaky, allowing fluid to seep out into the tissues, lowering the amount of fluid left in circulation. This combination of increased system volume and decreased fluid causes a dramatic decrease in blood pressure and reduces the blood flow to the organs. Other changes brought on by immune response may cause coagulation of the blood in the extremities, which can further decrease circulation through the organs.

Septic shock is seen most often in patients with suppressed immune systems, and is usually due to bacteria acquired during treatment at the hospital. Theimmune system is suppressed by drugs used to treat cancer, autoimmune disorders, organ transplants, and diseases of immune deficiency such as AIDS. Malnutrition, chronic drug abuse, and long-term illness increase the likelihood ofsuccumbing to bacterial infection. Bacteremia is more likely with preexistinginfections such as urinary or gastrointestinal tract infections, or skin ulcers. Bacteria may be introduced to the blood stream by surgical procedures, catheters, or intravenous equipment.

Toxic shock syndrome most often occurs in menstruating women using highly absorbent tampons. Left in place longer than other types, these tampons providethe breeding ground for Staphylococcus bacteria, which may then enterthe bloodstream through small tears in the vaginal lining. The incidence of toxic shock syndrome has declined markedly since this type of tampon was withdrawn from the market.

Septic shock is usually preceded by bacteremia, which is marked by fever, malaise, chills, and nausea. The first sign of shock is often confusion and decreased consciousness. In this beginning stage, the extremities are usually warm. Later, they become cool, pale, and bluish. Fever may give way to lower that normal temperatures later on in sepsis.

Other symptoms include:

  • Rapid heartbeat
  • Shallow, rapid breathing
  • Decreased urination.
  • Reddish patches in the skin.

Septic shock may progress to cause "adult respiratory distress syndrome," inwhich fluid collects in the lungs, and breathing becomes very shallow and labored. This condition may lead to ventilatory collapse, in which the patient can no longer breathe adequately without assistance.

Diagnosis of septic shock is made by measuring blood pressure, heart rate, and respiration rate, as well as by a consideration of possible sources of infection. Blood pressure may be monitored with a catheter device inserted into the pulmonary artery supplying the lungs (Swan-Ganz catheter). Blood culturesare done to determine the type of bacteria responsible. The levels of oxygen,carbon dioxide, and acidity in the blood are also monitored to assess changes in respiratory function.

Septic shock is treated initially with a combination of antibiotics and fluidreplacement. The antibiotic is chosen based on the bacteria present, although two or more types of antibiotics may be used initially until the organism is identified. Intravenous fluids, either blood or protein solutions, replacethe fluid lost by leakage. Coagulation and hemorrhage may be treated with transfusions of plasma or platelets. Dopamine may be given to increase blood pressure further if necessary.

Respiratory distress is treated with mechanical ventilation and supplementaloxygen, either using a nosepiece or a tube into the trachea through the throat.

Identification and treatment of the primary infection site is important to prevent ongoing proliferation of bacteria.

Septic shock is most likely to develop in the hospital, since it follows infections which are likely to be the objects of treatment. Because of this, careful monitoring and early, aggressive therapy can minimize the likelihood of progression. Nonetheless, death occurs in at least 25% of all cases.

The likelihood of recovery from septic shock depends on may factors, including the degree of immunosuppression of the patient, underlying disease, promptness of treatment, and type of bacteria responsible. Mortality is highest in the very young and the elderly, those with persistent or recurrent infection,and those with compromised immune systems.

The risk of developing septic shock can be minimized through treatment of underlying bacterial infections, and prompt attention to signs of bacteremia. Inthe hospital, scrupulous aseptic technique on the part of medical professionals lowers the risk of introducing bacteria into the bloodstream.

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