Septic shock
Septic shock is a severe and potentially life-threatening condition characterized by acute cardiovascular collapse due to a complex interaction between the immune system and infectious agents in the bloodstream. This condition is marked by persistent low blood pressure despite adequate fluid resuscitation, leading to inadequate oxygen and nutrient delivery to cells and, consequently, organ dysfunction. Common causes include infections from various pathogens like bacteria, viruses, and fungi, with certain risk factors such as a compromised immune system, chronic illnesses, and invasive medical devices increasing susceptibility. Symptoms often include fever, rapid heart rate, respiratory distress, and signs of organ failure.
Diagnosis typically involves a thorough medical history, physical examination, lab tests, and imaging studies to identify the source of infection. Prompt treatment is crucial and usually requires antibiotics, cardiovascular support, and sometimes surgical intervention to eliminate the source of infection. Preventative measures focus on maintaining good hygiene, managing chronic health issues, and ensuring timely vaccinations. The prognosis for septic shock can be serious, with mortality rates ranging from 40 to 70 percent, underscoring the importance of swift recognition and management.
Septic shock
- ANATOMY OR SYSTEM AFFECTED: Blood, cardiovascular system, circulatory system, heart, immune system
- ALSO KNOWN AS: Sepsis-associated organ dysfunction
Definition
Septic shock is acute cardiovascular collapse precipitated by a complex interaction between biochemical agents in the bloodstream and the body’s immune system as it attempts to respond to infectious agents. Arterial hypotension persists despite adequate fluid resuscitation. The circulatory system is unable to meet cells' metabolic demands: delivery of oxygen and nutrients and removal of waste products. Pumping and circulation fail, leading to reduced tissue perfusion and organ dysfunction. Mortality approaches 40 to 70 percent.
Causes
Infectious agents such as gram-positive and gram-negative bacteria, viruses, fungi, and yeast trigger an exaggerated immune inflammatory response. The lipopolysaccharide (LPS) shell on gram-negative bacteria is an extremely strong stimulator of systemic inflammation. Parasitic infections, such a malaria, may also cause septic shock, although this is much rarer. Occasionally, septic shock-like conditions have been seen with non-infectious causes, such as with cases of pancreatitis, burns, and major trauma.
Risk Factors
Substantive risk factors include a compromised immune system, thermal burns, malnutrition, extremes of age, chronic medical conditions, use of invasive medical devices, hospitalization, steroid administration, and urinary tract, respiratory, or abdominal infection. Recent research has demonstrated polymorphisms, genetic mutations, and dysregulation of cellular receptors that negatively affect the body’s recognition of and response to pathogens. There are several lifestyle factors that may increase the risk of septic shock, including alcohol misuse disorder and intravenous drug use, both of which can weaken the immune system. One study indicated obesity could be a contributing factor. Healthcare workers and those traveling to areas with endemic diseases are also at risk because they are higher risk of developing infections. Patients on immunosuppressant therapies, those who have had their spleen removed, and patients on ventilators are also at increased risk for septic shock.
Symptoms
Infection is heralded by fever, tachycardia, tachypnea, and abnormal white blood cell count. Respiratory distress or frank respiratory failure ensues. Myocardial depression, decreased cardiac output, and vasodilation lead to hypotension refractory and fluid resuscitation and may require vasopressor and hydrocortisone support. Peripheral pulses and capillary refill are diminished. A procoagulant state develops in an attempt to prevent the dissemination of pathogens, leading to coagulopathy and dermal petechiae and purpura. Renal and gastrointestinal function diminishes. Changes in cognitive function, gastrointestinal upset, decreased urination, fever, chills, and muscle aches are additional symptoms of septic shock.
Screening and Diagnosis
Diagnosis is incumbent on history, physical examination, clinical signs and symptoms, hematologic labs (blood culture, complete blood count, differential, immature to total neutrophil ratio, and serum lactate), acute-phase reactants and biomarkers (interleukin-6, adrenomedullin, C-reactive protein, and procalcitonin), and radiological evaluation of suspected source sites. In the twenty-first century, rapid diagnostic tests were being developed to detect biomarkers on pathogens, allowing for the early detection of septic shock.
Treatment and Therapy
Elimination of the infection source is vital to survival. Culture and sensitivity testing of infected sites to identify the causative organism allows selection of definitive antimicrobial therapy. Until culture results are known, empiric antibiotic therapy is required. Antibiotics should be administered within an hour of a diagnosis of sepsis. Newer microarray testing is allowing earlier identification of pathogens, leading to better definitive antibiotic therapy. Cardiovascular support includes adequate ventilation and oxygenation, vasopressor support, corticosteroids, and adequate hematologic parameters (platelets, red blood cells). In addition to antibiotics, removing the infection may require removing the source of the infection through medical intervention, providing intravenous immunomodulatory therapies, and giving supportive care for accompanying symptoms.
Prevention and Outcomes
Adequate nutrition, management of chronic illness, good handwashing technique, aseptic technique for sterile procedures, the avoidance of trauma or exposure to infectious agents, and the removal of unnecessary tubes and catheters in institutionalized and hospitalized persons reduces the incidence of infection and thus lowers the risk of an exaggerated inflammatory response and shock state. Staying up to date on vaccinations, following appropriate medical protocols, using antibiotics prudently, managing chronic health conditions, treating wounds and infections promptly, and making healthy lifestyle choices are additional ways to prevent septic shock.
Bibliography
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Evans, Timothy, and Mitchell P. Fink, editors. Mechanisms of Organ Dysfunction in Critical Illness. New York: Springer, 2002.
Klein, Deborah G. "Shock and Sepsis." In Introduction to Critical Care Nursing, edited by Mary Lou Sole, Deborah G. Klein, and Marthe J. Moseley. 5th ed., St. Louis, Mo.: Saunders/Elsevier, 2009.
"Septic Shock." MedlinePlus, 25 Nov. 2023, medlineplus.gov/ency/article/000668.htm. Accessed 9 Oct. 2024.
"Septic Shock." NHS Inform, 18 Jan. 2023, www.nhsinform.scot/illnesses-and-conditions/blood-and-lymph/septic-shock. Accessed 9 Oct. 2024.
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Tissari, Päivi, et al. "Accurate and Rapid Identification of Bacterial Species from Positive Blood Cultures with a DNA-based Microarray Platform." The Lancet, vol. 375, Jan. 2010, pp. 224-230.