Sepsis Definitions - The Body's Overreaction
-
Sepsis: Life-threatening organ dysfunction caused by a dysregulated host response to infection. Diagnosed via suspected infection plus an acute increase in SOFA score of ≥2 points.
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Septic Shock: A subset of sepsis with critical circulatory and metabolic abnormalities.
- Persistent hypotension requiring vasopressors to maintain MAP ≥65 mmHg.
- Serum lactate level >2 mmol/L despite adequate fluid resuscitation.

⭐ Lactate is a marker of tissue hypoperfusion; its elevation can identify high-risk patients even with normal blood pressure.
Screening Tools - Spotting Sepsis Early
- Goal: Rapidly identify patients with suspected infection who are likely to have poor outcomes. Key tools are SIRS and qSOFA for initial bedside assessment, especially in non-ICU settings.
| Criteria | SIRS (Systemic Inflammatory Response) | qSOFA (quick SOFA) |
|---|---|---|
| Use | High sensitivity, low specificity | Bedside screen for sepsis risk (non-ICU) |
| Threshold | ≥2 criteria | ≥2 criteria |
| Parameters | Temp >38°C/<36°C, HR >90, RR >20, WBC >12k/<4k | RR ≥22, GCS <15, SBP ≤100 |
- Hypotension (SBP ≤ 100 mmHg)
- Altered Mental Status (GCS < 15)
- Tachypnea (RR ≥ 22/min)
⭐ qSOFA is a risk stratification tool, not a diagnostic criterion for sepsis. It has better prognostic accuracy for in-hospital mortality than SIRS in patients outside the ICU.
- Clinical Workflow:
Organ Dysfunction - The Domino Effect
Sepsis triggers a systemic inflammatory cascade, leading to widespread endothelial damage and microvascular thrombosis, culminating in organ failure.

- Cardiovascular
- Hypotension (SBP < 90 mmHg, MAP < 65 mmHg)
- Tachycardia
- ↑ Serum lactate (> 2 mmol/L)
- Respiratory
- Tachypnea & increased work of breathing
- Hypoxemia (PaO2/FiO2 ratio < 300)
- Acute Respiratory Distress Syndrome (ARDS)
- Renal
- Oliguria (< 0.5 mL/kg/hr for > 2 hrs)
- ↑ Serum creatinine
- Central Nervous System (CNS)
- Altered mental status (GCS < 15)
- Delirium, confusion, or coma
- Hepatic
- ↑ Bilirubin (> 2 mg/dL)
- ↑ Transaminases (ALT/AST)
- Hematologic
- Thrombocytopenia (Platelets < 100,000/μL)
- Coagulopathy (INR > 1.5)
⭐ Lactate is not just a marker of tissue hypoxia but also contributes to cardiovascular depression and vasodilation.
Initial Workup - The First Hour
- Goal: Complete bundle within 1 hour of recognition.
- Administer 30 mL/kg crystalloid for hypotension or lactate ≥4 mmol/L.
- Start vasopressors if hypotensive during or after fluid resuscitation to maintain MAP ≥65 mmHg.
⭐ Repeat lactate measurement within 2-4 hours if the initial level is elevated (> 2 mmol/L) to guide resuscitation.
High-Yield Points - ⚡ Biggest Takeaways
- The qSOFA score (GCS < 15, RR ≥ 22, SBP ≤ 100) is a key bedside tool to identify high-risk patients.
- An elevated serum lactate (> 2 mmol/L) signifies tissue hypoperfusion, a hallmark of septic shock.
- Suspect sepsis with a known infection plus any sign of new-onset organ dysfunction.
- Draw blood cultures before giving antibiotics, but do not delay treatment.
- SIRS criteria are sensitive but not specific; use them to raise suspicion for organ failure.
- Prompt recognition is the most critical factor in reducing sepsis mortality.
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