Systemic Inflammatory Response Syndrome (SIRS)
Definition: An exaggerated defense response of the body to harmful stressors (infection,
trauma, surgery, etc.) aimed at localizing and eliminating the source of injury.
Criteria for Diagnosis (Any 2 required):
1. Body temperature > 38°C or < 36°C
2. Heart rate > 90 bpm
3. Respiratory rate > 20 breaths per minute or PaCO2 < 32 mmHg
4. Abnormal WBC count (>12,000/mm³ or <4,000/mm³ or >10% immature bands)
Pediatric SIRS: Must include an abnormal leukocyte count or temperature.
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Sepsis and Septic Shock
Sepsis: SIRS with a confirmed or suspected infection.
Severe Sepsis: Sepsis with organ dysfunction, hypoperfusion, or hypotension.
Septic Shock: Sepsis with hypotension despite adequate fluid resuscitation, leading to perfusion
abnormalities (e.g., lactic acidosis, oliguria, altered mental status).
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Stages of Sepsis and MODS (Multiple Organ Dysfunction Syndrome)
1. Stage I: Local inflammatory response (e.g., swelling, heat, pain).
2. Stage II: Compensatory anti-inflammatory response (CARS) attempts to balance immune
response.
3. Stage III: Proinflammatory SIRS, endothelial dysfunction, coagulopathy, and microthrombosis.
4. Stage IV: CARS takes over, causing immunosuppression.
5. Stage V: Progression to MODS, with persistent dysregulation leading to organ failure.
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Multiple Organ Dysfunction Syndrome (MODS)
Definition: Failure of two or more organ systems, requiring medical intervention to maintain
homeostasis.
Pathophysiology: Can result from SIRS or any type of shock due to the inability to maintain
organ perfusion and oxygenation.
