What is septic shock? |

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 the metabolic demands of cells: 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.

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, mutations,
and dysregulation of cellular receptors that negatively affect the body’s
recognition of and response to pathogens.

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.

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.

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).

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.

Bibliography

Dellinger, R. Phillip, et al. “Surviving Sepsis Campaign: International Guidelines for Management of Severe Sepsis and Septic Shock: 2008.” Critical Care Medicine 36 (2008): 296-327.

Evans, Timothy, and Mitchell P. Fink, eds. 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. Natl. Lib. of Medicine, 8 Feb. 2014. Web. 29 Dec. 2015.

Tissari, Päivi, et al. “Accurate and Rapid Identification of Bacterial Species from Positive Blood Cultures with a DNA-based Microarray Platform.” The Lancet 375 (January, 2010): 224-230.