SEPSIS AND SEPTIC SHOCK
DEFINITION AND PATHOPHYSIOLOGY
• Sepsis: Life-threatening organ dysfunction due to a dysregulated host response to infection.
• Septic shock: A subset with circulatory and cellular/metabolic dysfunction requiring vasopressors to maintain MAP >= 65 mm Hg and lactate > 2 mmol/L despite fluids.
• Pathophysiology: Excessive inflammation + immune suppression + microvascular injury -> multi-organ failure.
• 2001 SIRS: Host inflammatory response to infection and injury.
• 2016 Consensus conference SEPSIS-3 (2 categories):
- Sepsis (Without Shock): Infection + Organ dysfunction.
- Sepsis with Shock: Sepsis + Fluid resistant Hypotension (MAP > 65 + Lactate => 2 mmol/L).
EPIDEMIOLOGY
• 49 million cases and 11 million deaths globally each year.
• In the U.S., accounts for > 1/3 of in-hospital deaths.
BIOLOGICAL FEATURES
• Hyperinflammation: Neutrophil traps (NETs), cytokines, complement activation.
• Immunosuppression: Lymphopenia (Increased risk death), T-cell exhaustion, monocyte dysfunction/hypofunction. Neutrophils- hypofunctional, increased Myelopoiesis.
• Vascular injury: Glycocalyx loss, increased permeability, microthrombosis, decreased Fibrinolysis. Hypotension, third spacing of fluid and sometimes DIC.
COMMON CAUSES + RISK FACTORS
• Sites of infection: Lungs (40-60%), abdomen, GU tract, bloodstream, skin/soft tissue.
• Pathogens: Gram-positive/-negative bacteria, fungi (e.g., Candida), viruses.
• Risk factors: Advanced age, immunosuppression, chronic illness (e.g., ESRD, cancer), indwelling devices.
CLINICAL RECOGNITION
• Suspect in any acutely ill patient with infection + organ dysfunction.
• Symptoms: Fever/hypothermia, altered mentation, dyspnea, oliguria, hypotension, tachypnea.
• Labs: increased Lactate, leukocytosis/leukopenia, increased Cr, hyperglycemia, thrombocytopenia.
CLINICAL FEATURES OF SHOCK (Manifest in 3 windows to the body)
• The Peripheral Window:
- Cold
- Clammy
- Pale
- Discolored skin
- Decreased pulses
• The Renal Window:
- Decreased urine output < 0.5 ml/kg/hr
• The Neurologic Window:
- Altered mental status
DIAGNOSIS
• Use qSOFA or SOFA to assess organ dysfunction.
• qSOFA: HAT
- Hypotension SBP < 100 mm Hg
- AMS GCS < 15
- Tachypnea: resp rate > 22
• Measure lactate in all suspected cases.
• Obtain cultures prior to antibiotics.
• Use imaging and molecular tests to identify infection source.
INITIAL MANAGEMENT (FIRST HOUR BUNDLE)
• Measure lactate (repeat if > 2 mmol/L).
• Obtain cultures before antibiotics.
• Start broad-spectrum antibiotics within 1 hour.
• Fluid resuscitation: 30 mL/kg IV crystalloids. Serial boluses 250cc-1L.
• Lactated Ringers > Normal Saline.
• Vasopressors to maintain MAP >= 65 mm Hg if hypotension persists.
ADVANCED MANAGEMENT
• Vasopressors: Norepinephrine is first-line.
• Corticosteroids: Consider for refractory shock. Hydrocortisone + Fludrocortisone. Reduce shock duration, ventilation, ICU stay.
• Source control: Prompt removal/drainage of infection source (e.g., abscess, catheter).
• Avoid overresuscitation: Use balanced fluids and assess fluid responsiveness.
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