• Polytrauma is a cause of noninfectious SIRS
  • Sepsis is a cause of SIRS
  • Hypotension is a criterion for diagnosis
  • Cytokine has a role in the pathophysiology


Correct Answer : Hypotension is a criterion for diagnosis
Ref: Harrisons 17th edition 1696
Hypotension is not included in the diagnosing criteria of SIRS
Cytokines play a major role in the pathophysiology of SIRS. Cytokines can exert endocrine, paracrine, and autocrine effects. TNF- stimulates leukocytes and vascular endothelial cells to release other cytokines
SIRS is defined as 2 or more of the following variables :
  • Fever of more than 38°C (100.4°F) or less than 36°C (96.8°F)
  • Heart rate of more than 90 beats per minute
  • Respiratory rate of more than 24 breaths per minute
  • Abnormal white blood cell count (>12,000/µL or < 4,000/µL or >10% immature [band] forms)

SIRS is nonspecific and can be caused by ischemia, inflammation, trauma, infection, or several insults combined. Thus, SIRS is not always related to infection.
Noninfectious  causes of SIRS:

  • Acute mesenteric ischemia
  • Adrenal insufficiency
  • Autoimmune disorders
  • Burns
  • Chemical aspiration
  • Cirrhosis
  • Cutaneous vasculitis
  • Dehydration
  • Drug reaction
  • Electrical injuries
  • Erythema multiforme
  • Hemorrhagic shock
  • Hematologic malignancy
  • Intestinal perforation
  • Medication side effect – Eg, from theophylline
  • Myocardial infarction
  • Pancreatitis
  • Seizure
  • Substance abuse – Stimulants such as cocaine and amphetamines
  • Surgical procedures
  • Toxic epidermal necrolysis
  • Transfusion reactions
  • Upper gastrointestinal bleeding
  • Vasculitis

Sepsis – When SIRS is suspected or proven to be due to infection
Septic shock  -Sepsis with hypotension (arterial blood pressure <90 mmHg systolic, or 40 less than patient’s normal blood pressure) for at least 1 h despite adequate fluid resuscitation , or, Need for vasopressors to maintain systolic blood pressure of 90 mmHg or mean arterial pressure 70 mmHg.
Refractory septic shock  –   Septic shock that lasts for >1 h and does not respond to fluid or pressor administration.
Multiple-organ dysfunction syndrome (MODS) – Dysfunction of more than one organ, requiring intervention to maintain homeostasis.

All are true about SIRS except

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