- 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
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
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
Definitions
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.