Overview
This lecture focuses on distributive shock, specifically sepsis and anaphylaxis, covering their pathophysiology, clinical presentation, and emergency management.
Distributive Shock: Pathophysiology and General Features
- Distributive shock (vasodilatory shock) involves widespread vasodilation and maldistribution of intravascular volume.
- Leads to decreased cardiac output and impaired tissue perfusion.
- Main subtypes discussed: sepsis and anaphylaxis.
Sepsis and Systemic Inflammatory Response Syndrome (SIRS)
- SIRS is a systemic inflammatory response triggered by infection entering through skin, respiratory, GI, or GU tracts.
- SIRS criteria: temp <36°C or >38°C, HR >90, RR >20 or PaCO2 <32, WBC <4,000 or >12,000, bands >10%.
- Sepsis = SIRS + suspected/confirmed infection.
- Severe sepsis: sepsis with organ dysfunction; septic shock: refractory hypotension.
- Untreated, progression can lead to MODS (multi-organ dysfunction syndrome) and death.
Sepsis Management and Prevention
- Prevention: sterile technique for lines, catheter care, remove unnecessary lines promptly.
- Early recognition and intervention are key.
- Start with two large-bore IVs (IO if necessary); obtain cultures before antibiotics.
- Blood, urine, and wound cultures from different sites 15 minutes apart.
- Lactic acid >2 mmol/L is elevated; >4 mmol/L is poor prognosis.
- Complete initial assessments and interventions ideally within 1 hour; official window is 3 hours.
- Remove and culture indwelling catheters/lines present before symptoms.
- Interventions: oxygen, 30 mL/kg fluid bolus, vasopressors if fluids ineffective, repeat lactic acid after fluids.
- Fluid challenge: raise patient's feet and observe BP response.
Anaphylaxis: Causes and Pathophysiology
- Anaphylaxis is an acute allergic reaction caused by food, medications, insect stings, latex, or environmental triggers.
- IgE-mediated response activates mast cells, releasing histamine, eosinophils, prostaglandins.
- Histamine causes vasodilation, edema, pruritus, bronchospasm.
- Antihistamines used: diphenhydramine for H1, famotidine/pepsid for H2.
- Severity varies among individuals; first exposure may be mild, subsequent exposures more severe.
- Allergies can be hereditary; teach patients to avoid triggers and carry/use EpiPen.
Anaphylaxis Presentation and Management
- Mild: within 2 hours; nasal congestion, hives, tingling, warmth.
- Moderate: same as mild plus flushing, anxiety, coughing, airway edema, wheezing.
- Severe: within minutes; bronchospasm, airway closure, cyanosis, stridor, hypotension, GI symptoms, possible cardiac arrest.
- Monitor patients receiving epinephrine for tachycardia and recurrence (possible within 48 hours).
- Epi dosing: 0.3 mg IM (1:1,000) for adults; 0.01 mg/kg IM for children.
- Only give IV epi (1:10,000) if patient is coding.
- Adjunct medications: corticosteroids (solumedrol), diphenhydramine, famotidine/pepsid.
Key Terms & Definitions
- Distributive Shock — Shock from abnormal blood distribution due to vasodilation.
- Sepsis — Life-threatening organ dysfunction from a dysregulated infection response.
- SIRS — Systemic response to infection or inflammation.
- MODS — Multi-organ dysfunction syndrome; failure of two or more organ systems.
- Anaphylaxis — Severe, rapid allergic reaction causing systemic symptoms.
- IgE — Immunoglobulin involved in allergic responses and anaphylaxis.
- Histamine — Chemical mediator causing vasodilation and bronchospasm.
Action Items / Next Steps
- Review SIRS criteria and practice identifying sepsis.
- Review anaphylaxis management steps, including EpiPen use.
- Practice sterile technique skills for line and catheter care where applicable.
- Prepare for a separate neurogenic shock lecture.