Sepsis & Septic Shock

  • Sepsis is a clinical syndrome characterized by systemic inflammation due to infection.
  • Whenever there is infection there is a reaction from host involving various responses.

Systemic responses to infection:

  • · Fever
  • · Hypothermia
  • · Tachypnea
  • · Tachycardia.


There is a continuum of severity ranging from sepsis to severe sepsis and septic shock. A systemic inflammatory response to infection, in which there is fever or hypothermia, tachycardia, tachypnea, and evidence of inadequate blood flow to internal organs


Sepsis (Septic Shock) Definition Diagnosis and Pathophysiology


  • Presence of bacteria in blood.


  • Presence of organisms or their toxins in blood.



  • (Systemic Inflammatory Response Syndrome) Presents with 2 or more of the following:
  • • Fever
  • · Tachypnoea
  • · Tachycardia
  • · Leucocytosis
  • · Leucopenia.
  • Sepsis is microbial infection with SIRS.
  • Severe sepsis or sepsis syndrome – Sepsis with organ dysfunction.
  • Septic Shock – Sepsis with hypotension.
  • Refractory septic shock – Septic shock for more than 1 hour.
  • Multiple Organ Dysfunction Syndrome (MODS)­
  • Dysfunction of more than 1 organ, requiring inter­vention.
  • When the defence mechanism fails, there is dysfunc­tion of major organs.

The different stages are :

  • Septic shock Hypotension Organ dysfunction Death.
  • Sepsis is reversible but septic shock is usually not.


  • SIRS is an inflammatory reaction to various clinical insults (e.g., severe trauma or burn) manifested by 2 or more of the following:
  • Temperature >38°C or <36°C
  • Heart rate >90/min
  • Respiratory rate >20/min or PaCO2 <32 mm Hg
  • White blood cell (WBC) count >12,000/mm3, <4,000/mm3, or >10% immature forms (bands)
  • is systemic inflammatory response syndrome.
  • It may be infectious or a non-infectious syndrome. If there is infection, it is called sepsis.

Etiology :

  • Genitourinary system
  • Hepatobiliary tract
  • Gastrointestinal tract
  • Lungs
  • Indwelling catheter
  • Surgical wound
  • Decubitus ulcer

Spread :

  • By blood stream, local spread, systemic spread of signal molecules or toxins.
  • Blood cultures yield bacteria or fungi in severe sepsis and septic shock. 70% are gram negative or positive bacteria.


  • By blood culture.
  • Microscopic examination of infected material from local site.
  • Culture of micro-organisms from infected mate­rial from local site.

Differential Diagnosis Septic Shock

  • Hyponatremia due to other causes, e.g., SIADH, cirrhosis, vomiting
  • Abdominal pain due to other causes
  • Other types of shock, e.g., septic, cardiogenic, hypovolemic, anaphylactic
  • Hyperkalemia due to other causes, e.g., renal failure, rhabdomyolysis

Gram-negative bacteremia occurs in :

  • Diabetes mellitus Lymphoproliferative diseases
  • Cirrhosis of liver
  • Burns
  • Invasive procedures, devices
  • Treatment with drugs which cause neutropenia.

Gram-positive bacteremia occurs in :

  • Vascular catheterization Indwelling mechanical devices Burns
  • IV drug use.

Fungemia occurs in :

  • Immunosuppressed patients Neutropenia
  • After broad-spectrum treatment.

Increased risk

  • Age more than 50 years.
  • Primary site pulmonary, abdominal or.
  • Age extremes (very old and very young)
  • Impaired host (see Associated Conditions)
  • Community-acquired pneumonia
  • Critically ill patients
  • Indwelling catheters: Intravascular, urinary, biliary
  • neuromeningeal.
  • (From urinary tract or catheter there is less severe sepsis).


  • In sepsis, an imbalance between pro- and anti-inflammatory mediators at the site of infection results in widespread systemic inflammation that damages distant uninvolved tissues.
  • · Local spread – GIT, skin, blood
  • Dysregulated nitric oxide production and activation of the coagulation system are the main contributors to maldistribution of organ blood flow.
  • · Direct into blood stream (IV catheters)
  • Widespread endothelial damage and microvascular dysfunction leads to maldistribution of blood flow, causing impaired tissue oxygenation and resultant organ dysfunction.
  • · Low immune response (any microbe anywhere can cause septicemia)
  • · Endotoxins (act as super antigens).
  • The initial, overexuberant inflammatory response can progress to significant immunosuppression in the later stages of sepsis.
  • Microbial signals

    • When microorganisms invade body, certain signals are recognized by the individual like : LPS ­Lipopolysachharide or endotoxins, LPS-binding pro­tein-LBP which transfers LPS to CD14 on the surface of monocytes, macrophages, neutrophils. This causes release of TNF (Tumor necrosis factor) and signals amplify and spread.
  • Host response

    • Involves microbial signal molecules-Ieucocytes, hu­moral mediators, vascular endothelium, cytokines, phospholipid derived mediator, coagulation factors, complement, vascular endothelium.
    • Mediator for septic shock is probably inducible nitric oxide synthase (iNOS).


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